06 Dec, 2011
4 commits
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Move dma data to a superset ttm_dma_tt structure which herit
from ttm_tt. This allow driver that don't use dma functionalities
to not have to waste memory for it.V2 Rebase on top of no memory account changes (where/when is my
delorean when i need it ?)
V3 Make sure page list is initialized empty
V4 typo/syntax fixesSigned-off-by: Jerome Glisse
Reviewed-by: Thomas Hellstrom -
In TTM world the pages for the graphic drivers are kept in three different
pools: write combined, uncached, and cached (write-back). When the pages
are used by the graphic driver the graphic adapter via its built in MMU
(or AGP) programs these pages in. The programming requires the virtual address
(from the graphic adapter perspective) and the physical address (either System RAM
or the memory on the card) which is obtained using the pci_map_* calls (which does the
virtual to physical - or bus address translation). During the graphic application's
"life" those pages can be shuffled around, swapped out to disk, moved from the
VRAM to System RAM or vice-versa. This all works with the existing TTM pool code
- except when we want to use the software IOTLB (SWIOTLB) code to "map" the physical
addresses to the graphic adapter MMU. We end up programming the bounce buffer's
physical address instead of the TTM pool memory's and get a non-worky driver.
There are two solutions:
1) using the DMA API to allocate pages that are screened by the DMA API, or
2) using the pci_sync_* calls to copy the pages from the bounce-buffer and back.This patch fixes the issue by allocating pages using the DMA API. The second
is a viable option - but it has performance drawbacks and potential correctness
issues - think of the write cache page being bounced (SWIOTLB->TTM), the
WC is set on the TTM page and the copy from SWIOTLB not making it to the TTM
page until the page has been recycled in the pool (and used by another application).The bounce buffer does not get activated often - only in cases where we have
a 32-bit capable card and we want to use a page that is allocated above the
4GB limit. The bounce buffer offers the solution of copying the contents
of that 4GB page to an location below 4GB and then back when the operation has been
completed (or vice-versa). This is done by using the 'pci_sync_*' calls.
Note: If you look carefully enough in the existing TTM page pool code you will
notice the GFP_DMA32 flag is used - which should guarantee that the provided page
is under 4GB. It certainly is the case, except this gets ignored in two cases:
- If user specifies 'swiotlb=force' which bounces _every_ page.
- If user is using a Xen's PV Linux guest (which uses the SWIOTLB and the
underlaying PFN's aren't necessarily under 4GB).To not have this extra copying done the other option is to allocate the pages
using the DMA API so that there is not need to map the page and perform the
expensive 'pci_sync_*' calls.This DMA API capable TTM pool requires for this the 'struct device' to
properly call the DMA API. It also has to track the virtual and bus address of
the page being handed out in case it ends up being swapped out or de-allocated -
to make sure it is de-allocated using the proper's 'struct device'.Implementation wise the code keeps two lists: one that is attached to the
'struct device' (via the dev->dma_pools list) and a global one to be used when
the 'struct device' is unavailable (think shrinker code). The global list can
iterate over all of the 'struct device' and its associated dma_pool. The list
in dev->dma_pools can only iterate the device's dma_pool.
/[struct device_pool]\
/---------------------------------------------------| dev |
/ +-------| dma_pool |
/-----+------\ / \--------------------/
|struct device| /-->[struct dma_pool for WC]</ /[struct device_pool]\
| dma_pools +----+ /-| dev |
| ... | \--->[struct dma_pool for uncached]
[v1: Using swiotlb_nr_tbl instead of swiotlb_enabled]
[v2: Major overhaul - added 'inuse_list' to seperate used from inuse and reorder
the order of lists to get better performance.]
[v3: Added comments/and some logic based on review, Added Jerome tag]
[v4: rebase on top of ttm_tt & ttm_backend merge]
[v5: rebase on top of ttm memory accounting overhaul]
[v6: New rebase on top of more memory accouting changes]
[v7: well rebase on top of no memory accounting changes]
[v8: make sure pages list is initialized empty]
[v9: calll ttm_mem_global_free_page in unpopulate for accurate accountg]
Signed-off-by: Konrad Rzeszutek Wilk
Reviewed-by: Jerome Glisse
Acked-by: Thomas Hellstrom -
Move the page allocation and freeing to driver callback and
provide ttm code helper function for those.Most intrusive change, is the fact that we now only fully
populate an object this simplify some of code designed around
the page fault design.V2 Rebase on top of memory accounting overhaul
V3 New rebase on top of more memory accouting changes
V4 Rebase on top of no memory account changes (where/when is my
delorean when i need it ?)Signed-off-by: Jerome Glisse
Reviewed-by: Konrad Rzeszutek Wilk
Reviewed-by: Thomas Hellstrom -
Use the ttm_tt pages array for pages allocations, move the list
unwinding into the page allocation functions.Signed-off-by: Jerome Glisse
21 Jun, 2011
1 commit
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. and some comments to make it easier to understand.
Ackedby: Randy Dunlap
[v2: Added some more updates from Randy Dunlap]
Signed-off-by: Konrad Rzeszutek Wilk
Signed-off-by: Dave Airlie
23 Feb, 2011
2 commits
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This reverts commit 5a893fc28f0393adb7c885a871b8c59e623fd528.
This causes a use after free in the ttm free alloc pages path,
when it tries to get the be after the be has been destroyed.Signed-off-by: Dave Airlie
-
This makes the accounting when using 'debug_dma_dump_mappings()'
and CONFIG_DMA_API_DEBUG=y be assigned to the correct device
instead of 'fallback'.No functional change - just cosmetic.
Signed-off-by: Konrad Rzeszutek Wilk
28 Jan, 2011
1 commit
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This is right now limited to only non-pool constructs.
[v2: Fixed indentation issues, add review-by tag]
Reviewed-by: Thomas Hellstrom
Signed-off-by: Konrad Rzeszutek Wilk
Tested-by: Ian Campbell
07 Jul, 2010
1 commit
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Repeated ttm_page_alloc_init/fini fails noisily because the pool
manager kobj isn't zeroed out between uses (we could do just that but
statically allocated kobjects are generally considered a bad thing).
Move it to kzalloc'ed memory.Note that this patch drops the refcounting behavior of the pool
allocator init/fini functions: it would have led to a race condition
in its current form, and anyway it was never exploited.This fixes a regression with reloading kms modules at runtime, since
page allocator was introduced.Signed-off-by: Francisco Jerez
Signed-off-by: Dave Airlie
06 Apr, 2010
3 commits
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Sysfs interface allows user to configure pool allocator functionality and
change limits for the size of pool.Signed-off-by: Pauli Nieminen
Signed-off-by: Dave Airlie -
ttm_page_alloc_debugfs can be registered to output the state
of pools.Debugfs file will output number of pages freed from the pool,
number of pages in pool now and the lowes number of pages in
pool since previous shrink.Signed-off-by: Pauli Nieminen
Signed-off-by: Dave Airlie -
On AGP system we might allocate/free routinely uncached or wc memory,
changing page from cached (wb) to uc or wc is very expensive and involves
a lot of flushing. To improve performance this allocator use a pool
of uc,wc pages.Pools are protected with spinlocks to allow multiple threads to allocate pages
simultanously. Expensive operations are done outside of spinlock to maximize
concurrency.Pools are linked lists of pages that were recently freed. mm shrink callback
allows kernel to claim back pages when they are required for something else.Fixes:
* set_pages_array_wb handles highmem pages so we don't have to remove them
from pool.
* Add count parameter to ttm_put_pages to avoid looping in free code.
* Change looping from _safe to normal in pool fill error path.
* Initialize sum variable and make the loop prettier in get_num_unused_pages.* Moved pages_freed reseting inside the loop in ttm_page_pool_free.
* Add warning comment about spinlock context in ttm_page_pool_free.Based on Jerome Glisse's and Dave Airlie's pool allocator.
Signed-off-by: Jerome Glisse
Signed-off-by: Dave Airlie
Signed-off-by: Pauli Nieminen
Reviewed-by: Jerome Glisse
Signed-off-by: Dave Airlie
