15 Apr, 2015
2 commits
-
Memtest is a simple feature which fills the memory with a given set of
patterns and validates memory contents, if bad memory regions is detected
it reserves them via memblock API. Since memblock API is widely used by
other architectures this feature can be enabled outside of x86 world.This patch set promotes memtest to live under generic mm umbrella and
enables memtest feature for arm/arm64.It was reported that this patch set was useful for tracking down an issue
with some errant DMA on an arm64 platform.This patch (of 6):
There is nothing platform dependent in the core memtest code, so other
platforms might benefit from this feature too.[linux@roeck-us.net: MEMTEST depends on MEMBLOCK]
Signed-off-by: Vladimir Murzin
Acked-by: Will Deacon
Tested-by: Mark Rutland
Cc: Ingo Molnar
Cc: Thomas Gleixner
Cc: "H. Peter Anvin"
Cc: Catalin Marinas
Cc: Russell King
Cc: Paul Bolle
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
I've noticed that there is no interfaces exposed by CMA which would let me
fuzz what's going on in there.This small patchset exposes some information out to userspace, plus adds
the ability to trigger allocation and freeing from userspace.This patch (of 3):
Implement a simple debugfs interface to expose information about CMA areas
in the system.Useful for testing/sanity checks for CMA since it was impossible to
previously retrieve this information in userspace.Signed-off-by: Sasha Levin
Acked-by: Joonsoo Kim
Cc: Marek Szyprowski
Cc: Laura Abbott
Cc: Konrad Rzeszutek Wilk
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
18 Feb, 2015
1 commit
-
Signed-off-by: Al Viro
17 Feb, 2015
1 commit
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All callers of get_xip_mem() are now gone. Remove checks for it,
initialisers of it, documentation of it and the only implementation of it.
Also remove mm/filemap_xip.c as it is now empty. Also remove
documentation of the long-gone get_xip_page().Signed-off-by: Matthew Wilcox
Cc: Andreas Dilger
Cc: Boaz Harrosh
Cc: Christoph Hellwig
Cc: Dave Chinner
Cc: Jan Kara
Cc: Jens Axboe
Cc: Kirill A. Shutemov
Cc: Mathieu Desnoyers
Cc: Randy Dunlap
Cc: Ross Zwisler
Cc: Theodore Ts'o
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
14 Feb, 2015
2 commits
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With this patch kasan will be able to catch bugs in memory allocated by
slub. Initially all objects in newly allocated slab page, marked as
redzone. Later, when allocation of slub object happens, requested by
caller number of bytes marked as accessible, and the rest of the object
(including slub's metadata) marked as redzone (inaccessible).We also mark object as accessible if ksize was called for this object.
There is some places in kernel where ksize function is called to inquire
size of really allocated area. Such callers could validly access whole
allocated memory, so it should be marked as accessible.Code in slub.c and slab_common.c files could validly access to object's
metadata, so instrumentation for this files are disabled.Signed-off-by: Andrey Ryabinin
Signed-off-by: Dmitry Chernenkov
Cc: Dmitry Vyukov
Cc: Konstantin Serebryany
Signed-off-by: Andrey Konovalov
Cc: Yuri Gribov
Cc: Konstantin Khlebnikov
Cc: Sasha Levin
Cc: Christoph Lameter
Cc: Joonsoo Kim
Cc: Dave Hansen
Cc: Andi Kleen
Cc: Ingo Molnar
Cc: Thomas Gleixner
Cc: "H. Peter Anvin"
Cc: Christoph Lameter
Cc: Pekka Enberg
Cc: David Rientjes
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Kernel Address sanitizer (KASan) is a dynamic memory error detector. It
provides fast and comprehensive solution for finding use-after-free and
out-of-bounds bugs.KASAN uses compile-time instrumentation for checking every memory access,
therefore GCC > v4.9.2 required. v4.9.2 almost works, but has issues with
putting symbol aliases into the wrong section, which breaks kasan
instrumentation of globals.This patch only adds infrastructure for kernel address sanitizer. It's
not available for use yet. The idea and some code was borrowed from [1].Basic idea:
The main idea of KASAN is to use shadow memory to record whether each byte
of memory is safe to access or not, and use compiler's instrumentation to
check the shadow memory on each memory access.Address sanitizer uses 1/8 of the memory addressable in kernel for shadow
memory and uses direct mapping with a scale and offset to translate a
memory address to its corresponding shadow address.Here is function to translate address to corresponding shadow address:
unsigned long kasan_mem_to_shadow(unsigned long addr)
{
return (addr >> KASAN_SHADOW_SCALE_SHIFT) + KASAN_SHADOW_OFFSET;
}where KASAN_SHADOW_SCALE_SHIFT = 3.
So for every 8 bytes there is one corresponding byte of shadow memory.
The following encoding used for each shadow byte: 0 means that all 8 bytes
of the corresponding memory region are valid for access; k (1
Acked-by: Michal Marek
Signed-off-by: Andrey Konovalov
Cc: Dmitry Vyukov
Cc: Konstantin Serebryany
Cc: Dmitry Chernenkov
Cc: Yuri Gribov
Cc: Konstantin Khlebnikov
Cc: Sasha Levin
Cc: Christoph Lameter
Cc: Joonsoo Kim
Cc: Dave Hansen
Cc: Andi Kleen
Cc: Ingo Molnar
Cc: Thomas Gleixner
Cc: "H. Peter Anvin"
Cc: Christoph Lameter
Cc: Pekka Enberg
Cc: David Rientjes
Cc: Stephen Rothwell
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
11 Feb, 2015
1 commit
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remap_file_pages(2) was invented to be able efficiently map parts of
huge file into limited 32-bit virtual address space such as in database
workloads.Nonlinear mappings are pain to support and it seems there's no
legitimate use-cases nowadays since 64-bit systems are widely available.Let's drop it and get rid of all these special-cased code.
The patch replaces the syscall with emulation which creates new VMA on
each remap_file_pages(), unless they it can be merged with an adjacent
one.I didn't find *any* real code that uses remap_file_pages(2) to test
emulation impact on. I've checked Debian code search and source of all
packages in ALT Linux. No real users: libc wrappers, mentions in
strace, gdb, valgrind and this kind of stuff.There are few basic tests in LTP for the syscall. They work just fine
with emulation.To test performance impact, I've written small test case which
demonstrate pretty much worst case scenario: map 4G shmfs file, write to
begin of every page pgoff of the page, remap pages in reverse order,
read every page.The test creates 1 million of VMAs if emulation is in use, so I had to
set vm.max_map_count to 1100000 to avoid -ENOMEM.Before: 23.3 ( +- 4.31% ) seconds
After: 43.9 ( +- 0.85% ) seconds
Slowdown: 1.88xI believe we can live with that.
Test case:
#define _GNU_SOURCE
#include
#include
#include
#include#define MB (1024UL * 1024)
#define SIZE (4096 * MB)int main(int argc, char **argv)
{
unsigned long *p;
long i, pass;for (pass = 0; pass < 10; pass++) {
p = mmap(NULL, SIZE, PROT_READ|PROT_WRITE,
MAP_SHARED | MAP_ANONYMOUS, -1, 0);
if (p == MAP_FAILED) {
perror("mmap");
return -1;
}for (i = 0; i < SIZE / 4096; i++)
p[i * 4096 / sizeof(*p)] = i;for (i = 0; i < SIZE / 4096; i++) {
if (remap_file_pages(p + i * 4096 / sizeof(*p), 4096,
0, (SIZE - 4096 * (i + 1)) >> 12, 0)) {
perror("remap_file_pages");
return -1;
}
}for (i = SIZE / 4096 - 1; i >= 0; i--)
assert(p[i * 4096 / sizeof(*p)] == SIZE / 4096 - i - 1);munmap(p, SIZE);
}return 0;
}[akpm@linux-foundation.org: fix spello]
[sasha.levin@oracle.com: initialize populate before usage]
[sasha.levin@oracle.com: grab file ref to prevent race while mmaping]
Signed-off-by: "Kirill A. Shutemov"
Cc: Peter Zijlstra
Cc: Ingo Molnar
Cc: Dave Jones
Cc: Linus Torvalds
Cc: Armin Rigo
Signed-off-by: Sasha Levin
Cc: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
14 Dec, 2014
2 commits
-
This is the page owner tracking code which is introduced so far ago. It
is resident on Andrew's tree, though, nobody tried to upstream so it
remain as is. Our company uses this feature actively to debug memory leak
or to find a memory hogger so I decide to upstream this feature.This functionality help us to know who allocates the page. When
allocating a page, we store some information about allocation in extra
memory. Later, if we need to know status of all pages, we can get and
analyze it from this stored information.In previous version of this feature, extra memory is statically defined in
struct page, but, in this version, extra memory is allocated outside of
struct page. It enables us to turn on/off this feature at boottime
without considerable memory waste.Although we already have tracepoint for tracing page allocation/free,
using it to analyze page owner is rather complex. We need to enlarge the
trace buffer for preventing overlapping until userspace program launched.
And, launched program continually dump out the trace buffer for later
analysis and it would change system behaviour with more possibility rather
than just keeping it in memory, so bad for debug.Moreover, we can use page_owner feature further for various purposes. For
example, we can use it for fragmentation statistics implemented in this
patch. And, I also plan to implement some CMA failure debugging feature
using this interface.I'd like to give the credit for all developers contributed this feature,
but, it's not easy because I don't know exact history. Sorry about that.
Below is people who has "Signed-off-by" in the patches in Andrew's tree.Contributor:
Alexander Nyberg
Mel Gorman
Dave Hansen
Minchan Kim
Michal Nazarewicz
Andrew Morton
Jungsoo SonSigned-off-by: Joonsoo Kim
Cc: Mel Gorman
Cc: Johannes Weiner
Cc: Minchan Kim
Cc: Dave Hansen
Cc: Michal Nazarewicz
Cc: Jungsoo Son
Cc: Ingo Molnar
Cc: Joonsoo Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
When we debug something, we'd like to insert some information to every
page. For this purpose, we sometimes modify struct page itself. But,
this has drawbacks. First, it requires re-compile. This makes us
hesitate to use the powerful debug feature so development process is
slowed down. And, second, sometimes it is impossible to rebuild the
kernel due to third party module dependency. At third, system behaviour
would be largely different after re-compile, because it changes size of
struct page greatly and this structure is accessed by every part of
kernel. Keeping this as it is would be better to reproduce errornous
situation.This feature is intended to overcome above mentioned problems. This
feature allocates memory for extended data per page in certain place
rather than the struct page itself. This memory can be accessed by the
accessor functions provided by this code. During the boot process, it
checks whether allocation of huge chunk of memory is needed or not. If
not, it avoids allocating memory at all. With this advantage, we can
include this feature into the kernel in default and can avoid rebuild and
solve related problems.Until now, memcg uses this technique. But, now, memcg decides to embed
their variable to struct page itself and it's code to extend struct page
has been removed. I'd like to use this code to develop debug feature, so
this patch resurrect it.To help these things to work well, this patch introduces two callbacks for
clients. One is the need callback which is mandatory if user wants to
avoid useless memory allocation at boot-time. The other is optional, init
callback, which is used to do proper initialization after memory is
allocated. Detailed explanation about purpose of these functions is in
code comment. Please refer it.Others are completely same with previous extension code in memcg.
Signed-off-by: Joonsoo Kim
Cc: Mel Gorman
Cc: Johannes Weiner
Cc: Minchan Kim
Cc: Dave Hansen
Cc: Michal Nazarewicz
Cc: Jungsoo Son
Cc: Ingo Molnar
Cc: Joonsoo Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
11 Dec, 2014
2 commits
-
Now that the external page_cgroup data structure and its lookup is gone,
the only code remaining in there is swap slot accounting.Rename it and move the conditional compilation into mm/Makefile.
Signed-off-by: Johannes Weiner
Acked-by: Michal Hocko
Acked-by: Vladimir Davydov
Acked-by: David S. Miller
Acked-by: KAMEZAWA Hiroyuki
Cc: "Kirill A. Shutemov"
Cc: Tejun Heo
Cc: Joonsoo Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Memory is internally accounted in bytes, using spinlock-protected 64-bit
counters, even though the smallest accounting delta is a page. The
counter interface is also convoluted and does too many things.Introduce a new lockless word-sized page counter API, then change all
memory accounting over to it. The translation from and to bytes then only
happens when interfacing with userspace.The removed locking overhead is noticable when scaling beyond the per-cpu
charge caches - on a 4-socket machine with 144-threads, the following test
shows the performance differences of 288 memcgs concurrently running a
page fault benchmark:vanilla:
18631648.500498 task-clock (msec) # 140.643 CPUs utilized ( +- 0.33% )
1,380,638 context-switches # 0.074 K/sec ( +- 0.75% )
24,390 cpu-migrations # 0.001 K/sec ( +- 8.44% )
1,843,305,768 page-faults # 0.099 M/sec ( +- 0.00% )
50,134,994,088,218 cycles # 2.691 GHz ( +- 0.33% )
stalled-cycles-frontend
stalled-cycles-backend
8,049,712,224,651 instructions # 0.16 insns per cycle ( +- 0.04% )
1,586,970,584,979 branches # 85.176 M/sec ( +- 0.05% )
1,724,989,949 branch-misses # 0.11% of all branches ( +- 0.48% )132.474343877 seconds time elapsed ( +- 0.21% )
lockless:
12195979.037525 task-clock (msec) # 133.480 CPUs utilized ( +- 0.18% )
832,850 context-switches # 0.068 K/sec ( +- 0.54% )
15,624 cpu-migrations # 0.001 K/sec ( +- 10.17% )
1,843,304,774 page-faults # 0.151 M/sec ( +- 0.00% )
32,811,216,801,141 cycles # 2.690 GHz ( +- 0.18% )
stalled-cycles-frontend
stalled-cycles-backend
9,999,265,091,727 instructions # 0.30 insns per cycle ( +- 0.10% )
2,076,759,325,203 branches # 170.282 M/sec ( +- 0.12% )
1,656,917,214 branch-misses # 0.08% of all branches ( +- 0.55% )91.369330729 seconds time elapsed ( +- 0.45% )
On top of improved scalability, this also gets rid of the icky long long
types in the very heart of memcg, which is great for 32 bit and also makes
the code a lot more readable.Notable differences between the old and new API:
- res_counter_charge() and res_counter_charge_nofail() become
page_counter_try_charge() and page_counter_charge() resp. to match
the more common kernel naming scheme of try_do()/do()- res_counter_uncharge_until() is only ever used to cancel a local
counter and never to uncharge bigger segments of a hierarchy, so
it's replaced by the simpler page_counter_cancel()- res_counter_set_limit() is replaced by page_counter_limit(), which
expects its callers to serialize against themselves- res_counter_memparse_write_strategy() is replaced by
page_counter_limit(), which rounds down to the nearest page size -
rather than up. This is more reasonable for explicitely requested
hard upper limits.- to keep charging light-weight, page_counter_try_charge() charges
speculatively, only to roll back if the result exceeds the limit.
Because of this, a failing bigger charge can temporarily lock out
smaller charges that would otherwise succeed. The error is bounded
to the difference between the smallest and the biggest possible
charge size, so for memcg, this means that a failing THP charge can
send base page charges into reclaim upto 2MB (4MB) before the limit
would have been reached. This should be acceptable.[akpm@linux-foundation.org: add includes for WARN_ON_ONCE and memparse]
[akpm@linux-foundation.org: add includes for WARN_ON_ONCE, memparse, strncmp, and PAGE_SIZE]
Signed-off-by: Johannes Weiner
Acked-by: Michal Hocko
Acked-by: Vladimir Davydov
Cc: Tejun Heo
Cc: David Rientjes
Cc: Stephen Rothwell
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
12 Oct, 2014
1 commit
-
Pull tinification fix from Josh "Paper Bag" Triplett:
"Fixup to use PATCHv2 of 'mm: Support compiling out madvise and
fadvise'"* tag 'tiny/no-advice-fixup-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/josh/linux:
mm: Support fadvise without CONFIG_MMU
11 Oct, 2014
1 commit
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Commit d3ac21cacc24790eb45d735769f35753f5b56ceb ("mm: Support compiling
out madvise and fadvise") incorrectly made fadvise conditional on
CONFIG_MMU. (The merged branch unintentionally incorporated v1 of the
patch rather than the fixed v2.) Apply the delta from v1 to v2, to
allow fadvise without CONFIG_MMU.Reported-by: Johannes Weiner
Signed-off-by: Josh Triplett
10 Oct, 2014
2 commits
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Always mark pages with PageBalloon even if balloon compaction is disabled
and expose this mark in /proc/kpageflags as KPF_BALLOON.Also this patch adds three counters into /proc/vmstat: "balloon_inflate",
"balloon_deflate" and "balloon_migrate". They accumulate balloon
activity. Current size of balloon is (balloon_inflate - balloon_deflate)
pages.All generic balloon code now gathered under option CONFIG_MEMORY_BALLOON.
It should be selected by ballooning driver which wants use this feature.
Currently virtio-balloon is the only user.Signed-off-by: Konstantin Khlebnikov
Cc: Rafael Aquini
Cc: Andrey Ryabinin
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
dump_page() and dump_vma() are not specific to page_alloc.c, move them out
so page_alloc.c won't turn into the unofficial debug repository.Signed-off-by: Sasha Levin
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
18 Aug, 2014
1 commit
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Many embedded systems will not need these syscalls, and omitting them
saves space. Add a new EXPERT config option CONFIG_ADVISE_SYSCALLS
(default y) to support compiling them out.bloat-o-meter:
add/remove: 0/3 grow/shrink: 0/0 up/down: 0/-2250 (-2250)
function old new delta
sys_fadvise64 57 - -57
sys_fadvise64_64 691 - -691
sys_madvise 1502 - -1502Signed-off-by: Josh Triplett
07 Aug, 2014
2 commits
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Add zpool api.
zpool provides an interface for memory storage, typically of compressed
memory. Users can select what backend to use; currently the only
implementations are zbud, a low density implementation with up to two
compressed pages per storage page, and zsmalloc, a higher density
implementation with multiple compressed pages per storage page.Signed-off-by: Dan Streetman
Tested-by: Seth Jennings
Cc: Minchan Kim
Cc: Nitin Gupta
Cc: Weijie Yang
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Currently, there are two users on CMA functionality, one is the DMA
subsystem and the other is the KVM on powerpc. They have their own code
to manage CMA reserved area even if they looks really similar. From my
guess, it is caused by some needs on bitmap management. KVM side wants
to maintain bitmap not for 1 page, but for more size. Eventually it use
bitmap where one bit represents 64 pages.When I implement CMA related patches, I should change those two places
to apply my change and it seem to be painful to me. I want to change
this situation and reduce future code management overhead through this
patch.This change could also help developer who want to use CMA in their new
feature development, since they can use CMA easily without copying &
pasting this reserved area management code.In previous patches, we have prepared some features to generalize CMA
reserved area management and now it's time to do it. This patch moves
core functions to mm/cma.c and change DMA APIs to use these functions.There is no functional change in DMA APIs.
Signed-off-by: Joonsoo Kim
Acked-by: Michal Nazarewicz
Acked-by: Zhang Yanfei
Acked-by: Minchan Kim
Reviewed-by: Aneesh Kumar K.V
Cc: Alexander Graf
Cc: Aneesh Kumar K.V
Cc: Gleb Natapov
Acked-by: Marek Szyprowski
Tested-by: Marek Szyprowski
Cc: Paolo Bonzini
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
05 Jun, 2014
1 commit
-
mm/memory.c is overloaded: over 4k lines. get_user_pages() code is
pretty much self-contained let's move it to separate file.No other changes made.
Signed-off-by: Kirill A. Shutemov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
20 May, 2014
1 commit
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Continue moving some of the block files that are scattered around.
bounce.c contains only code for bouncing the contents of a bio.
It's block proper code, not mm code.Suggested-by: Ming Lei
Signed-off-by: Jens Axboe
13 Apr, 2014
1 commit
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Pull vfs updates from Al Viro:
"The first vfs pile, with deep apologies for being very late in this
window.Assorted cleanups and fixes, plus a large preparatory part of iov_iter
work. There's a lot more of that, but it'll probably go into the next
merge window - it *does* shape up nicely, removes a lot of
boilerplate, gets rid of locking inconsistencie between aio_write and
splice_write and I hope to get Kent's direct-io rewrite merged into
the same queue, but some of the stuff after this point is having
(mostly trivial) conflicts with the things already merged into
mainline and with some I want more testing.This one passes LTP and xfstests without regressions, in addition to
usual beating. BTW, readahead02 in ltp syscalls testsuite has started
giving failures since "mm/readahead.c: fix readahead failure for
memoryless NUMA nodes and limit readahead pages" - might be a false
positive, might be a real regression..."* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (63 commits)
missing bits of "splice: fix racy pipe->buffers uses"
cifs: fix the race in cifs_writev()
ceph_sync_{,direct_}write: fix an oops on ceph_osdc_new_request() failure
kill generic_file_buffered_write()
ocfs2_file_aio_write(): switch to generic_perform_write()
ceph_aio_write(): switch to generic_perform_write()
xfs_file_buffered_aio_write(): switch to generic_perform_write()
export generic_perform_write(), start getting rid of generic_file_buffer_write()
generic_file_direct_write(): get rid of ppos argument
btrfs_file_aio_write(): get rid of ppos
kill the 5th argument of generic_file_buffered_write()
kill the 4th argument of __generic_file_aio_write()
lustre: don't open-code kernel_recvmsg()
ocfs2: don't open-code kernel_recvmsg()
drbd: don't open-code kernel_recvmsg()
constify blk_rq_map_user_iov() and friends
lustre: switch to kernel_sendmsg()
ocfs2: don't open-code kernel_sendmsg()
take iov_iter stuff to mm/iov_iter.c
process_vm_access: tidy up a bit
...
08 Apr, 2014
2 commits
-
This patch creates a generic implementation of early_ioremap() support
based on the existing x86 implementation. early_ioremp() is useful for
early boot code which needs to temporarily map I/O or memory regions
before normal mapping functions such as ioremap() are available.Some architectures have optional MMU. In the no-MMU case, the remap
functions simply return the passed in physical address and the unmap
functions do nothing.Signed-off-by: Mark Salter
Acked-by: Catalin Marinas
Acked-by: H. Peter Anvin
Cc: Borislav Petkov
Cc: Dave Young
Cc: Will Deacon
Cc: Ingo Molnar
Cc: Thomas Gleixner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This patch is a continuation of efforts trying to optimize find_vma(),
avoiding potentially expensive rbtree walks to locate a vma upon faults.
The original approach (https://lkml.org/lkml/2013/11/1/410), where the
largest vma was also cached, ended up being too specific and random,
thus further comparison with other approaches were needed. There are
two things to consider when dealing with this, the cache hit rate and
the latency of find_vma(). Improving the hit-rate does not necessarily
translate in finding the vma any faster, as the overhead of any fancy
caching schemes can be too high to consider.We currently cache the last used vma for the whole address space, which
provides a nice optimization, reducing the total cycles in find_vma() by
up to 250%, for workloads with good locality. On the other hand, this
simple scheme is pretty much useless for workloads with poor locality.
Analyzing ebizzy runs shows that, no matter how many threads are
running, the mmap_cache hit rate is less than 2%, and in many situations
below 1%.The proposed approach is to replace this scheme with a small per-thread
cache, maximizing hit rates at a very low maintenance cost.
Invalidations are performed by simply bumping up a 32-bit sequence
number. The only expensive operation is in the rare case of a seq
number overflow, where all caches that share the same address space are
flushed. Upon a miss, the proposed replacement policy is based on the
page number that contains the virtual address in question. Concretely,
the following results are seen on an 80 core, 8 socket x86-64 box:1) System bootup: Most programs are single threaded, so the per-thread
scheme does improve ~50% hit rate by just adding a few more slots to
the cache.+----------------+----------+------------------+
| caching scheme | hit-rate | cycles (billion) |
+----------------+----------+------------------+
| baseline | 50.61% | 19.90 |
| patched | 73.45% | 13.58 |
+----------------+----------+------------------+2) Kernel build: This one is already pretty good with the current
approach as we're dealing with good locality.+----------------+----------+------------------+
| caching scheme | hit-rate | cycles (billion) |
+----------------+----------+------------------+
| baseline | 75.28% | 11.03 |
| patched | 88.09% | 9.31 |
+----------------+----------+------------------+3) Oracle 11g Data Mining (4k pages): Similar to the kernel build workload.
+----------------+----------+------------------+
| caching scheme | hit-rate | cycles (billion) |
+----------------+----------+------------------+
| baseline | 70.66% | 17.14 |
| patched | 91.15% | 12.57 |
+----------------+----------+------------------+4) Ebizzy: There's a fair amount of variation from run to run, but this
approach always shows nearly perfect hit rates, while baseline is just
about non-existent. The amounts of cycles can fluctuate between
anywhere from ~60 to ~116 for the baseline scheme, but this approach
reduces it considerably. For instance, with 80 threads:+----------------+----------+------------------+
| caching scheme | hit-rate | cycles (billion) |
+----------------+----------+------------------+
| baseline | 1.06% | 91.54 |
| patched | 99.97% | 14.18 |
+----------------+----------+------------------+[akpm@linux-foundation.org: fix nommu build, per Davidlohr]
[akpm@linux-foundation.org: document vmacache_valid() logic]
[akpm@linux-foundation.org: attempt to untangle header files]
[akpm@linux-foundation.org: add vmacache_find() BUG_ON]
[hughd@google.com: add vmacache_valid_mm() (from Oleg)]
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: adjust and enhance comments]
Signed-off-by: Davidlohr Bueso
Reviewed-by: Rik van Riel
Acked-by: Linus Torvalds
Reviewed-by: Michel Lespinasse
Cc: Oleg Nesterov
Tested-by: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
04 Apr, 2014
1 commit
-
The VM maintains cached filesystem pages on two types of lists. One
list holds the pages recently faulted into the cache, the other list
holds pages that have been referenced repeatedly on that first list.
The idea is to prefer reclaiming young pages over those that have shown
to benefit from caching in the past. We call the recently usedbut
ultimately was not significantly better than a FIFO policy and still
thrashed cache based on eviction speed, rather than actual demand for
cache.This patch solves one half of the problem by decoupling the ability to
detect working set changes from the inactive list size. By maintaining
a history of recently evicted file pages it can detect frequently used
pages with an arbitrarily small inactive list size, and subsequently
apply pressure on the active list based on actual demand for cache, not
just overall eviction speed.Every zone maintains a counter that tracks inactive list aging speed.
When a page is evicted, a snapshot of this counter is stored in the
now-empty page cache radix tree slot. On refault, the minimum access
distance of the page can be assessed, to evaluate whether the page
should be part of the active list or not.This fixes the VM's blindness towards working set changes in excess of
the inactive list. And it's the foundation to further improve the
protection ability and reduce the minimum inactive list size of 50%.Signed-off-by: Johannes Weiner
Reviewed-by: Rik van Riel
Reviewed-by: Minchan Kim
Reviewed-by: Bob Liu
Cc: Andrea Arcangeli
Cc: Christoph Hellwig
Cc: Dave Chinner
Cc: Greg Thelen
Cc: Hugh Dickins
Cc: Jan Kara
Cc: KOSAKI Motohiro
Cc: Luigi Semenzato
Cc: Mel Gorman
Cc: Metin Doslu
Cc: Michel Lespinasse
Cc: Ozgun Erdogan
Cc: Peter Zijlstra
Cc: Roman Gushchin
Cc: Ryan Mallon
Cc: Tejun Heo
Cc: Vlastimil Babka
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
02 Apr, 2014
1 commit
-
Signed-off-by: Al Viro
31 Jan, 2014
1 commit
-
This patch moves zsmalloc under mm directory.
Before that, description will explain why we have needed custom
allocator.Zsmalloc is a new slab-based memory allocator for storing compressed
pages. It is designed for low fragmentation and high allocation success
rate on large object, but
Acked-by: Nitin Gupta
Reviewed-by: Konrad Rzeszutek Wilk
Cc: Bob Liu
Cc: Greg Kroah-Hartman
Cc: Hugh Dickins
Cc: Jens Axboe
Cc: Luigi Semenzato
Cc: Mel Gorman
Cc: Pekka Enberg
Cc: Rik van Riel
Cc: Seth Jennings
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
11 Sep, 2013
1 commit
-
Several subsystems use the same construct for LRU lists - a list head, a
spin lock and and item count. They also use exactly the same code for
adding and removing items from the LRU. Create a generic type for these
LRU lists.This is the beginning of generic, node aware LRUs for shrinkers to work
with.[glommer@openvz.org: enum defined constants for lru. Suggested by gthelen, don't relock over retry]
Signed-off-by: Dave Chinner
Signed-off-by: Glauber Costa
Reviewed-by: Greg Thelen
Acked-by: Mel Gorman
Cc: "Theodore Ts'o"
Cc: Adrian Hunter
Cc: Al Viro
Cc: Artem Bityutskiy
Cc: Arve Hjønnevåg
Cc: Carlos Maiolino
Cc: Christoph Hellwig
Cc: Chuck Lever
Cc: Daniel Vetter
Cc: David Rientjes
Cc: Gleb Natapov
Cc: Greg Thelen
Cc: J. Bruce Fields
Cc: Jan Kara
Cc: Jerome Glisse
Cc: John Stultz
Cc: KAMEZAWA Hiroyuki
Cc: Kent Overstreet
Cc: Kirill A. Shutemov
Cc: Marcelo Tosatti
Cc: Mel Gorman
Cc: Steven Whitehouse
Cc: Thomas Hellstrom
Cc: Trond Myklebust
Signed-off-by: Andrew MortonSigned-off-by: Al Viro
11 Jul, 2013
2 commits
-
zswap is a thin backend for frontswap that takes pages that are in the
process of being swapped out and attempts to compress them and store
them in a RAM-based memory pool. This can result in a significant I/O
reduction on the swap device and, in the case where decompressing from
RAM is faster than reading from the swap device, can also improve
workload performance.It also has support for evicting swap pages that are currently
compressed in zswap to the swap device on an LRU(ish) basis. This
functionality makes zswap a true cache in that, once the cache is full,
the oldest pages can be moved out of zswap to the swap device so newer
pages can be compressed and stored in zswap.This patch adds the zswap driver to mm/
Signed-off-by: Seth Jennings
Acked-by: Rik van Riel
Cc: Greg Kroah-Hartman
Cc: Nitin Gupta
Cc: Minchan Kim
Cc: Konrad Rzeszutek Wilk
Cc: Dan Magenheimer
Cc: Robert Jennings
Cc: Jenifer Hopper
Cc: Mel Gorman
Cc: Johannes Weiner
Cc: Larry Woodman
Cc: Benjamin Herrenschmidt
Cc: Dave Hansen
Cc: Joe Perches
Cc: Joonsoo Kim
Cc: Cody P Schafer
Cc: Hugh Dickens
Cc: Paul Mackerras
Cc: Fengguang Wu
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
zbud is an special purpose allocator for storing compressed pages. It
is designed to store up to two compressed pages per physical page.
While this design limits storage density, it has simple and
deterministic reclaim properties that make it preferable to a higher
density approach when reclaim will be used.zbud works by storing compressed pages, or "zpages", together in pairs
in a single memory page called a "zbud page". The first buddy is "left
justifed" at the beginning of the zbud page, and the last buddy is
"right justified" at the end of the zbud page. The benefit is that if
either buddy is freed, the freed buddy space, coalesced with whatever
slack space that existed between the buddies, results in the largest
possible free region within the zbud page.zbud also provides an attractive lower bound on density. The ratio of
zpages to zbud pages can not be less than 1. This ensures that zbud can
never "do harm" by using more pages to store zpages than the
uncompressed zpages would have used on their own.This implementation is a rewrite of the zbud allocator internally used
by zcache in the driver/staging tree. The rewrite was necessary to
remove some of the zcache specific elements that were ingrained
throughout and provide a generic allocation interface that can later be
used by zsmalloc and others.This patch adds zbud to mm/ for later use by zswap.
Signed-off-by: Seth Jennings
Acked-by: Rik van Riel
Cc: Greg Kroah-Hartman
Cc: Nitin Gupta
Cc: Minchan Kim
Cc: Konrad Rzeszutek Wilk
Cc: Dan Magenheimer
Cc: Robert Jennings
Cc: Jenifer Hopper
Cc: Mel Gorman
Cc: Johannes Weiner
Cc: Larry Woodman
Cc: Benjamin Herrenschmidt
Cc: Dave Hansen
Cc: Joe Perches
Cc: Joonsoo Kim
Cc: Cody P Schafer
Cc: Hugh Dickens
Cc: Paul Mackerras
Cc: Bob Liu
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
30 Apr, 2013
1 commit
-
With this patch userland applications that want to maintain the
interactivity/memory allocation cost can use the pressure level
notifications. The levels are defined like this:The "low" level means that the system is reclaiming memory for new
allocations. Monitoring this reclaiming activity might be useful for
maintaining cache level. Upon notification, the program (typically
"Activity Manager") might analyze vmstat and act in advance (i.e.
prematurely shutdown unimportant services).The "medium" level means that the system is experiencing medium memory
pressure, the system might be making swap, paging out active file
caches, etc. Upon this event applications may decide to further analyze
vmstat/zoneinfo/memcg or internal memory usage statistics and free any
resources that can be easily reconstructed or re-read from a disk.The "critical" level means that the system is actively thrashing, it is
about to out of memory (OOM) or even the in-kernel OOM killer is on its
way to trigger. Applications should do whatever they can to help the
system. It might be too late to consult with vmstat or any other
statistics, so it's advisable to take an immediate action.The events are propagated upward until the event is handled, i.e. the
events are not pass-through. Here is what this means: for example you
have three cgroups: A->B->C. Now you set up an event listener on
cgroups A, B and C, and suppose group C experiences some pressure. In
this situation, only group C will receive the notification, i.e. groups
A and B will not receive it. This is done to avoid excessive
"broadcasting" of messages, which disturbs the system and which is
especially bad if we are low on memory or thrashing. So, organize the
cgroups wisely, or propagate the events manually (or, ask us to
implement the pass-through events, explaining why would you need them.)Performance wise, the memory pressure notifications feature itself is
lightweight and does not require much of bookkeeping, in contrast to the
rest of memcg features. Unfortunately, as of current memcg
implementation, pages accounting is an inseparable part and cannot be
turned off. The good news is that there are some efforts[1] to improve
the situation; plus, implementing the same, fully API-compatible[2]
interface for CONFIG_MEMCG=n case (e.g. embedded) is also a viable
option, so it will not require any changes on the userland side.[1] http://permalink.gmane.org/gmane.linux.kernel.cgroups/6291
[2] http://lkml.org/lkml/2013/2/21/454[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix CONFIG_CGROPUPS=n warnings]
Signed-off-by: Anton Vorontsov
Acked-by: Kirill A. Shutemov
Acked-by: KAMEZAWA Hiroyuki
Cc: Tejun Heo
Cc: David Rientjes
Cc: Pekka Enberg
Cc: Mel Gorman
Cc: Glauber Costa
Cc: Michal Hocko
Cc: Luiz Capitulino
Cc: Greg Thelen
Cc: Leonid Moiseichuk
Cc: KOSAKI Motohiro
Cc: Minchan Kim
Cc: Bartlomiej Zolnierkiewicz
Cc: John Stultz
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
12 Dec, 2012
1 commit
-
Memory fragmentation introduced by ballooning might reduce significantly
the number of 2MB contiguous memory blocks that can be used within a guest,
thus imposing performance penalties associated with the reduced number of
transparent huge pages that could be used by the guest workload.This patch introduces a common interface to help a balloon driver on
making its page set movable to compaction, and thus allowing the system
to better leverage the compation efforts on memory defragmentation.[akpm@linux-foundation.org: use PAGE_FLAGS_CHECK_AT_PREP, s/__balloon_page_flags/page_flags_cleared/, small cleanups]
[rientjes@google.com: allow balloon compaction for any system with memory compaction enabled, which is the defconfig]
Signed-off-by: Rafael Aquini
Acked-by: Mel Gorman
Cc: Rusty Russell
Cc: "Michael S. Tsirkin"
Cc: Rik van Riel
Cc: Andi Kleen
Cc: Konrad Rzeszutek Wilk
Cc: Minchan Kim
Signed-off-by: David Rientjes
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
09 Oct, 2012
1 commit
-
Implement an interval tree as a replacement for the VMA prio_tree. The
algorithms are similar to lib/interval_tree.c; however that code can't be
directly reused as the interval endpoints are not explicitly stored in the
VMA. So instead, the common algorithm is moved into a template and the
details (node type, how to get interval endpoints from the node, etc) are
filled in using the C preprocessor.Once the interval tree functions are available, using them as a
replacement to the VMA prio tree is a relatively simple, mechanical job.Signed-off-by: Michel Lespinasse
Cc: Rik van Riel
Cc: Hillf Danton
Cc: Peter Zijlstra
Cc: Catalin Marinas
Cc: Andrea Arcangeli
Cc: David Woodhouse
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
01 Aug, 2012
3 commits
-
mm/page_alloc.c has some memory isolation functions but they are used only
when we enable CONFIG_{CMA|MEMORY_HOTPLUG|MEMORY_FAILURE}. So let's make
it configurable by new CONFIG_MEMORY_ISOLATION so that it can reduce
binary size and we can check it simple by CONFIG_MEMORY_ISOLATION, not if
defined CONFIG_{CMA|MEMORY_HOTPLUG|MEMORY_FAILURE}.Signed-off-by: Minchan Kim
Cc: Andi Kleen
Cc: Marek Szyprowski
Acked-by: KAMEZAWA Hiroyuki
Cc: KOSAKI Motohiro
Cc: Mel Gorman
Cc: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Sanity:
CONFIG_CGROUP_MEM_RES_CTLR -> CONFIG_MEMCG
CONFIG_CGROUP_MEM_RES_CTLR_SWAP -> CONFIG_MEMCG_SWAP
CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED -> CONFIG_MEMCG_SWAP_ENABLED
CONFIG_CGROUP_MEM_RES_CTLR_KMEM -> CONFIG_MEMCG_KMEM[mhocko@suse.cz: fix missed bits]
Cc: Glauber Costa
Acked-by: Michal Hocko
Cc: Johannes Weiner
Cc: KAMEZAWA Hiroyuki
Cc: Hugh Dickins
Cc: Tejun Heo
Cc: Aneesh Kumar K.V
Cc: David Rientjes
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Implement a new controller that allows us to control HugeTLB allocations.
The extension allows to limit the HugeTLB usage per control group and
enforces the controller limit during page fault. Since HugeTLB doesn't
support page reclaim, enforcing the limit at page fault time implies that,
the application will get SIGBUS signal if it tries to access HugeTLB pages
beyond its limit. This requires the application to know beforehand how
much HugeTLB pages it would require for its use.The charge/uncharge calls will be added to HugeTLB code in later patch.
Support for cgroup removal will be added in later patches.[akpm@linux-foundation.org: s/CONFIG_CGROUP_HUGETLB_RES_CTLR/CONFIG_MEMCG_HUGETLB/g]
[akpm@linux-foundation.org: s/CONFIG_MEMCG_HUGETLB/CONFIG_CGROUP_HUGETLB/g]
Reviewed-by: KAMEZAWA Hiroyuki
Signed-off-by: Aneesh Kumar K.V
Cc: David Rientjes
Cc: Hillf Danton
Reviewed-by: Michal Hocko
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
31 Jul, 2012
1 commit
-
Pull SLAB changes from Pekka Enberg:
"Most of the changes included are from Christoph Lameter's "common
slab" patch series that unifies common parts of SLUB, SLAB, and SLOB
allocators. The unification is needed for Glauber Costa's "kmem
memcg" work that will hopefully appear for v3.7.The rest of the changes are fixes and speedups by various people."
* 'slab/next' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux: (32 commits)
mm: Fix build warning in kmem_cache_create()
slob: Fix early boot kernel crash
mm, slub: ensure irqs are enabled for kmemcheck
mm, sl[aou]b: Move kmem_cache_create mutex handling to common code
mm, sl[aou]b: Use a common mutex definition
mm, sl[aou]b: Common definition for boot state of the slab allocators
mm, sl[aou]b: Extract common code for kmem_cache_create()
slub: remove invalid reference to list iterator variable
mm: Fix signal SIGFPE in slabinfo.c.
slab: move FULL state transition to an initcall
slab: Fix a typo in commit 8c138b "slab: Get rid of obj_size macro"
mm, slab: Build fix for recent kmem_cache changes
slab: rename gfpflags to allocflags
slub: refactoring unfreeze_partials()
slub: use __cmpxchg_double_slab() at interrupt disabled place
slab/mempolicy: always use local policy from interrupt context
slab: Get rid of obj_size macro
mm, sl[aou]b: Extract common fields from struct kmem_cache
slab: Remove some accessors
slab: Use page struct fields instead of casting
...
09 Jul, 2012
1 commit
-
Kmem_cache_create() does a variety of sanity checks but those
vary depending on the allocator. Use the strictest tests and put them into
a slab_common file. Make the tests conditional on CONFIG_DEBUG_VM.This patch has the effect of adding sanity checks for SLUB and SLOB
under CONFIG_DEBUG_VM and removes the checks in SLAB for !CONFIG_DEBUG_VM.Signed-off-by: Christoph Lameter
Signed-off-by: Pekka Enberg
05 Jun, 2012
1 commit
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Pull frontswap feature from Konrad Rzeszutek Wilk:
"Frontswap provides a "transcendent memory" interface for swap pages.
In some environments, dramatic performance savings may be obtained
because swapped pages are saved in RAM (or a RAM-like device) instead
of a swap disk. This tag provides the basic infrastructure along with
some changes to the existing backends."Fix up trivial conflict in mm/Makefile due to removal of swap token code
changing a line next to the new frontswap entry.This pull request came in before the merge window even opened, it got
delayed to after the merge window by me just wanting to make sure it had
actual users. Apparently IBM is using this on their embedded side, and
Jan Beulich says that it's already made available for SLES and OpenSUSE
users.Also acked by Rik van Riel, and Konrad points to other people liking it
too. So in it goes.By Dan Magenheimer (4) and Konrad Rzeszutek Wilk (2)
via Konrad Rzeszutek Wilk
* tag 'stable/frontswap.v16-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/mm:
frontswap: s/put_page/store/g s/get_page/load
MAINTAINER: Add myself for the frontswap API
mm: frontswap: config and doc files
mm: frontswap: core frontswap functionality
mm: frontswap: core swap subsystem hooks and headers
mm: frontswap: add frontswap header file
30 May, 2012
2 commits
-
Add a Kconfig option to allow people who don't want cross memory attach to
not have it included in their build.Signed-off-by: Chris Yeoh
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The swap token code no longer fits in with the current VM model. It
does not play well with cgroups or the better NUMA placement code in
development, since we have only one swap token globally.It also has the potential to mess with scalability of the system, by
increasing the number of non-reclaimable pages on the active and
inactive anon LRU lists.Last but not least, the swap token code has been broken for a year
without complaints, as reported by Konstantin Khlebnikov. This suggests
we no longer have much use for it.The days of sub-1G memory systems with heavy use of swap are over. If
we ever need thrashing reducing code in the future, we will have to
implement something that does scale.Signed-off-by: Rik van Riel
Cc: Konstantin Khlebnikov
Acked-by: Johannes Weiner
Cc: Mel Gorman
Cc: Hugh Dickins
Acked-by: Bob Picco
Acked-by: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
