20 Jan, 2017
1 commit
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Mike reported that he could trigger the WARN_ON_ONCE() in
set_sched_clock_stable() using hotplug.This exposed a fundamental problem with the interface, we should never
mark the TSC stable if we ever find it to be unstable. Therefore
set_sched_clock_stable() is a broken interface.The reason it existed is that not having it is a pain, it means all
relevant architecture code needs to call clear_sched_clock_stable()
where appropriate.Of the three architectures that select HAVE_UNSTABLE_SCHED_CLOCK ia64
and parisc are trivial in that they never called
set_sched_clock_stable(), so add an unconditional call to
clear_sched_clock_stable() to them.For x86 the story is a lot more involved, and what this patch tries to
do is ensure we preserve the status quo. So even is Cyrix or Transmeta
have usable TSC they never called set_sched_clock_stable() so they now
get an explicit mark unstable.Reported-by: Mike Galbraith
Signed-off-by: Peter Zijlstra (Intel)
Cc: Borislav Petkov
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Fixes: 9881b024b7d7 ("sched/clock: Delay switching sched_clock to stable")
Link: http://lkml.kernel.org/r/20170119133633.GB6536@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar
19 Jan, 2017
1 commit
-
Scheduling to the max performance core is enabled by
default for Turbo Boost Maxt Technology 3.0 capable platforms.Remove the useless sysctl_sched_itmt_enabled check to
update sched topology for adding the prioritized core scheduling
flag.Signed-off-by: Tim Chen
Cc: Peter Zijlstra
Cc: Mike Galbraith
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Srinivas Pandruvada
Cc: Thomas Gleixner
Cc: bp@suse.de
Cc: jolsa@redhat.com
Cc: linux-acpi@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: rjw@rjwysocki.net
Link: http://lkml.kernel.org/r/1484778629-4404-1-git-send-email-tim.c.chen@linux.intel.com
Signed-off-by: Ingo Molnar
15 Jan, 2017
1 commit
-
Mike noticed this bogosity:
> > +# define mutex_lock_nest_io(lock, nest_lock) mutex_io(lock)
> ^^^^^^^^^^^^^^ typoThis new locking API is not used yet, so this didn't trigger in testing.
Fix it.
Reported-by: Mike Galbraith
Cc: Tejun Heo
Cc: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Jens Axboe
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: adilger.kernel@dilger.ca
Cc: jack@suse.com
Cc: kernel-team@fb.com
Cc: mingbo@fb.com
Cc: tytso@mit.edu
Signed-off-by: Ingo Molnar
14 Jan, 2017
37 commits
-
When an ext4 fs is bogged down by a lot of metadata IOs (in the
reported case, it was deletion of millions of files, but any massive
amount of journal writes would do), after the journal is filled up,
tasks which try to access the filesystem and aren't currently
performing the journal writes end up waiting in
__jbd2_log_wait_for_space() for journal->j_checkpoint_mutex.Because those mutex sleeps aren't marked as iowait, this condition can
lead to misleadingly low iowait and /proc/stat:procs_blocked. While
iowait propagation is far from strict, this condition can be triggered
fairly easily and annotating these sleeps correctly helps initial
diagnosis quite a bit.Use the new mutex_lock_io() for journal->j_checkpoint_mutex so that
these sleeps are properly marked as iowait.Reported-by: Mingbo Wan
Signed-off-by: Tejun Heo
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andreas Dilger
Cc: Andrew Morton
Cc: Jan Kara
Cc: Jens Axboe
Cc: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Theodore Ts'o
Cc: Thomas Gleixner
Cc: kernel-team@fb.com
Link: http://lkml.kernel.org/r/1477673892-28940-5-git-send-email-tj@kernel.org
Signed-off-by: Ingo Molnar -
We sometimes end up propagating IO blocking through mutexes; however,
because there currently is no way of annotating mutex sleeps as
iowait, there are cases where iowait and /proc/stat:procs_blocked
report misleading numbers obscuring the actual state of the system.This patch adds mutex_lock_io() so that mutex sleeps can be marked as
iowait in those cases.Signed-off-by: Tejun Heo
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Jens Axboe
Cc: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: adilger.kernel@dilger.ca
Cc: jack@suse.com
Cc: kernel-team@fb.com
Cc: mingbo@fb.com
Cc: tytso@mit.edu
Link: http://lkml.kernel.org/r/1477673892-28940-4-git-send-email-tj@kernel.org
Signed-off-by: Ingo Molnar -
Now that IO schedule accounting is done inside __schedule(),
io_schedule() can be split into three steps - prep, schedule, and
finish - where the schedule part doesn't need any special annotation.
This allows marking a sleep as iowait by simply wrapping an existing
blocking function with io_schedule_prepare() and io_schedule_finish().Because task_struct->in_iowait is single bit, the caller of
io_schedule_prepare() needs to record and the pass its state to
io_schedule_finish() to be safe regarding nesting. While this isn't
the prettiest, these functions are mostly gonna be used by core
functions and we don't want to use more space for ->in_iowait.While at it, as it's simple to do now, reimplement io_schedule()
without unnecessarily going through io_schedule_timeout().Signed-off-by: Tejun Heo
Signed-off-by: Peter Zijlstra (Intel)
Cc: Andrew Morton
Cc: Jens Axboe
Cc: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: adilger.kernel@dilger.ca
Cc: jack@suse.com
Cc: kernel-team@fb.com
Cc: mingbo@fb.com
Cc: tytso@mit.edu
Link: http://lkml.kernel.org/r/1477673892-28940-3-git-send-email-tj@kernel.org
Signed-off-by: Ingo Molnar -
For an interface to support blocking for IOs, it must call
io_schedule() instead of schedule(). This makes it tedious to add IO
blocking to existing interfaces as the switching between schedule()
and io_schedule() is often buried deep.As we already have a way to mark the task as IO scheduling, this can
be made easier by separating out io_schedule() into multiple steps so
that IO schedule preparation can be performed before invoking a
blocking interface and the actual accounting happens inside the
scheduler.io_schedule_timeout() does the following three things prior to calling
schedule_timeout().1. Mark the task as scheduling for IO.
2. Flush out plugged IOs.
3. Account the IO scheduling.done close to the actual scheduling. This patch moves #3 into the
scheduler so that later patches can separate out preparation and
finish steps from io_schedule().Patch-originally-by: Peter Zijlstra
Signed-off-by: Tejun Heo
Signed-off-by: Peter Zijlstra (Intel)
Cc: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: adilger.kernel@dilger.ca
Cc: akpm@linux-foundation.org
Cc: axboe@kernel.dk
Cc: jack@suse.com
Cc: kernel-team@fb.com
Cc: mingbo@fb.com
Cc: tytso@mit.edu
Link: http://lkml.kernel.org/r/20161207204841.GA22296@htj.duckdns.org
Signed-off-by: Ingo Molnar -
Signed-off-by: Dietmar Eggemann
Signed-off-by: Peter Zijlstra (Intel)
Cc: Linus Torvalds
Cc: Mike Galbraith
Cc: Paul Turner
Cc: Peter Zijlstra
Cc: Samuel Thibault
Cc: Thomas Gleixner
Link: http://lkml.kernel.org/r/e9a4d858-bcf3-36b9-e3a9-449953e34569@arm.com
Signed-off-by: Ingo Molnar -
The update of the share of a cfs_rq is done when its load_avg is updated
but before the group_entity's load_avg has been updated for the past time
slot. This generates wrong load_avg accounting which can be significant
when small tasks are involved in the scheduling.Let take the example of a task a that is dequeued of its task group A:
root
(cfs_rq)
\
(se)
A
(cfs_rq)
\
(se)
aTask "a" was the only task in task group A which becomes idle when a is
dequeued.We have the sequence:
- dequeue_entity a->se
- update_load_avg(a->se)
- dequeue_entity_load_avg(A->cfs_rq, a->se)
- update_cfs_shares(A->cfs_rq)
A->cfs_rq->load.weight == 0
A->se->load.weight is updated with the new share (0 in this case)
- dequeue_entity A->se
- update_load_avg(A->se) but its weight is now null so the last time
slot (up to a tick) will be accounted with a weight of 0 instead of
its real weight during the time slot. The last time slot will be
accounted as an idle one whereas it was a running one.If the running time of task a is short enough that no tick happens when it
runs, all running time of group entity A->se will be accounted as idle
time.Instead, we should update the share of a cfs_rq (in fact the weight of its
group entity) only after having updated the load_avg of the group_entity.update_cfs_shares() now takes the sched_entity as a parameter instead of the
cfs_rq, and the weight of the group_entity is updated only once its load_avg
has been synced with current time.Signed-off-by: Vincent Guittot
Signed-off-by: Peter Zijlstra (Intel)
Cc: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: pjt@google.com
Link: http://lkml.kernel.org/r/1482335426-7664-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar -
Documentation/scheduler/completion.txt says this about complete_all():
"calls complete_all() to signal all current and future waiters."
Which doesn't strictly match the current semantics. Currently
complete_all() is equivalent to UINT_MAX/2 complete() invocations,
which is distinctly less than 'all current and future waiters'
(enumerable vs innumerable), although it has worked in practice.However, Dmitry had a weird case where it might matter, so change
completions to use saturation semantics for complete()/complete_all().
Once done hits UINT_MAX (and complete_all() sets it there) it will
never again be decremented.Requested-by: Dmitry Torokhov
Signed-off-by: Peter Zijlstra (Intel)
Cc: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: der.herr@hofr.at
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar -
This patch allows for reading the current (leftover) runtime and
absolute deadline of a SCHED_DEADLINE task through /proc/*/sched
(entries dl.runtime and dl.deadline), while debugging/testing.Signed-off-by: Tommaso Cucinotta
Signed-off-by: Peter Zijlstra (Intel)
Reviewed-by: Juri Lelli
Reviewed-by: Luca Abeni
Acked-by: Daniel Bistrot de Oliveira
Cc: Juri Lelli
Cc: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Link: http://lkml.kernel.org/r/1477473437-10346-2-git-send-email-tommaso.cucinotta@sssup.it
Signed-off-by: Ingo Molnar -
When switching between the unstable and stable variants it is
currently possible that clock discontinuities occur.And while these will mostly be 'small', attempt to do better.
As observed on my IVB-EP, the sched_clock() is ~1.5s ahead of the
ktime_get_ns() based timeline at the point of switchover
(sched_clock_init_late()) after SMP bringup.Equally, when the TSC is later found to be unstable -- typically
because SMM tries to hide its SMI latencies by mucking with the TSC --
we want to avoid large jumps.Since the clocksource watchdog reports the issue after the fact we
cannot exactly fix up time, but since SMI latencies are typically
small (~10ns range), the discontinuity is mainly due to drift between
sched_clock() and ktime_get_ns() (which on my desktop is ~79s over
24days).I dislike this patch because it adds overhead to the good case in
favour of dealing with badness. But given the widespread failure of
TSC stability this is worth it.Note that in case the TSC makes drastic jumps after SMP bringup we're
still hosed. There's just not much we can do in that case without
stupid overhead.If we were to somehow expose tsc_clocksource_reliable (which is hard
because this code is also used on ia64 and parisc) we could avoid some
of the newly introduced overhead.Signed-off-by: Peter Zijlstra (Intel)
Cc: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar -
Currently we switch to the stable sched_clock if we guess the TSC is
usable, and then switch back to the unstable path if it turns out TSC
isn't stable during SMP bringup after all.Delay switching to the stable path until after SMP bringup is
complete. This way we'll avoid switching during the time we detect the
worst of the TSC offences.Signed-off-by: Peter Zijlstra (Intel)
Cc: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar -
sched_clock was still using the deprecated static_key interface.
Signed-off-by: Peter Zijlstra (Intel)
Cc: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar -
PeterZ reported that we'd fail to mark the TSC unstable when the
clocksource watchdog finds it unsuitable.Allow a clocksource to run a custom action when its being marked
unstable and hook up the TSC unstable code.Reported-by: Peter Zijlstra (Intel)
Signed-off-by: Thomas Gleixner
Signed-off-by: Peter Zijlstra (Intel)
Cc: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar -
There's no diagnostic checks for figuring out when we've accidentally
missed update_rq_clock() calls. Let's add some by piggybacking on the
rq_*pin_lock() wrappers.The idea behind the diagnostic checks is that upon pining rq lock the
rq clock should be updated, via update_rq_clock(), before anybody
reads the clock with rq_clock() or rq_clock_task().The exception to this rule is when updates have explicitly been
disabled with the rq_clock_skip_update() optimisation.There are some functions that only unpin the rq lock in order to grab
some other lock and avoid deadlock. In that case we don't need to
update the clock again and the previous diagnostic state can be
carried over in rq_repin_lock() by saving the state in the rq_flags
context.Since this patch adds a new clock update flag and some already exist
in rq::clock_skip_update, that field has now been renamed. An attempt
has been made to keep the flag manipulation code small and fast since
it's used in the heart of the __schedule() fast path.For the !CONFIG_SCHED_DEBUG case the only object code change (other
than addresses) is the following change to reset RQCF_ACT_SKIP inside
of __schedule(),- c7 83 38 09 00 00 00 movl $0x0,0x938(%rbx)
- 00 00 00
+ 83 a3 38 09 00 00 fc andl $0xfffffffc,0x938(%rbx)Suggested-by: Peter Zijlstra
Signed-off-by: Matt Fleming
Signed-off-by: Peter Zijlstra (Intel)
Cc: Byungchul Park
Cc: Frederic Weisbecker
Cc: Jan Kara
Cc: Linus Torvalds
Cc: Luca Abeni
Cc: Mel Gorman
Cc: Mike Galbraith
Cc: Mike Galbraith
Cc: Petr Mladek
Cc: Rik van Riel
Cc: Sergey Senozhatsky
Cc: Thomas Gleixner
Cc: Wanpeng Li
Cc: Yuyang Du
Link: http://lkml.kernel.org/r/20160921133813.31976-8-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar -
Address this rq-clock update bug:
WARNING: CPU: 30 PID: 195 at ../kernel/sched/sched.h:797 set_next_entity()
rq->clock_update_flags < RQCF_ACT_SKIPCall Trace:
dump_stack()
__warn()
warn_slowpath_fmt()
set_next_entity()
? _raw_spin_lock()
set_curr_task_fair()
set_user_nice.part.85()
set_user_nice()
create_worker()
worker_thread()
kthread()
ret_from_fork()Signed-off-by: Peter Zijlstra (Intel)
Cc: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar -
Add the update_rq_clock() call at the top of the callstack instead of
at the bottom where we find it missing, this to aid later effort to
minimize the number of update_rq_lock() calls.WARNING: CPU: 30 PID: 194 at ../kernel/sched/sched.h:797 assert_clock_updated()
rq->clock_update_flags < RQCF_ACT_SKIPCall Trace:
dump_stack()
__warn()
warn_slowpath_fmt()
assert_clock_updated.isra.63.part.64()
can_migrate_task()
load_balance()
pick_next_task_fair()
__schedule()
schedule()
worker_thread()
kthread()Signed-off-by: Peter Zijlstra (Intel)
Cc: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar -
Instead of adding the update_rq_clock() all the way at the bottom of
the callstack, add one at the top, this to aid later effort to
minimize update_rq_lock() calls.WARNING: CPU: 0 PID: 1 at ../kernel/sched/sched.h:797 detach_task_cfs_rq()
rq->clock_update_flags < RQCF_ACT_SKIPCall Trace:
dump_stack()
__warn()
warn_slowpath_fmt()
detach_task_cfs_rq()
switched_from_fair()
__sched_setscheduler()
_sched_setscheduler()
sched_set_stop_task()
cpu_stop_create()
__smpboot_create_thread.part.2()
smpboot_register_percpu_thread_cpumask()
cpu_stop_init()
do_one_initcall()
? print_cpu_info()
kernel_init_freeable()
? rest_init()
kernel_init()
ret_from_fork()Signed-off-by: Peter Zijlstra (Intel)
Cc: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar -
Address this rq-clock update bug:
WARNING: CPU: 0 PID: 0 at ../kernel/sched/sched.h:797 post_init_entity_util_avg()
rq->clock_update_flags < RQCF_ACT_SKIPCall Trace:
__warn()
post_init_entity_util_avg()
wake_up_new_task()
_do_fork()
kernel_thread()
rest_init()
start_kernel()Signed-off-by: Peter Zijlstra (Intel)
Cc: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar -
Future patches will emit warnings if rq_clock() is called before
update_rq_clock() inside a rq_pin_lock()/rq_unpin_lock() pair.Since there is only one caller of idle_balance() we can push the
unpin/repin there.Signed-off-by: Matt Fleming
Signed-off-by: Peter Zijlstra (Intel)
Cc: Byungchul Park
Cc: Frederic Weisbecker
Cc: Jan Kara
Cc: Linus Torvalds
Cc: Luca Abeni
Cc: Mel Gorman
Cc: Mike Galbraith
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Petr Mladek
Cc: Rik van Riel
Cc: Sergey Senozhatsky
Cc: Thomas Gleixner
Cc: Wanpeng Li
Cc: Yuyang Du
Link: http://lkml.kernel.org/r/20160921133813.31976-7-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar -
rq_clock() is called from sched_info_{depart,arrive}() after resetting
RQCF_ACT_SKIP but prior to a call to update_rq_clock().In preparation for pending patches that check whether the rq clock has
been updated inside of a pin context before rq_clock() is called, move
the reset of rq->clock_skip_update immediately before unpinning the rq
lock.This will avoid the new warnings which check if update_rq_clock() is
being actively skipped.Signed-off-by: Matt Fleming
Signed-off-by: Peter Zijlstra (Intel)
Cc: Byungchul Park
Cc: Frederic Weisbecker
Cc: Jan Kara
Cc: Linus Torvalds
Cc: Luca Abeni
Cc: Mel Gorman
Cc: Mike Galbraith
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Petr Mladek
Cc: Rik van Riel
Cc: Sergey Senozhatsky
Cc: Thomas Gleixner
Cc: Wanpeng Li
Cc: Yuyang Du
Link: http://lkml.kernel.org/r/20160921133813.31976-6-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar -
In preparation for adding diagnostic checks to catch missing calls to
update_rq_clock(), provide wrappers for (re)pinning and unpinning
rq->lock.Because the pending diagnostic checks allow state to be maintained in
rq_flags across pin contexts, swap the 'struct pin_cookie' arguments
for 'struct rq_flags *'.Signed-off-by: Matt Fleming
Signed-off-by: Peter Zijlstra (Intel)
Cc: Byungchul Park
Cc: Frederic Weisbecker
Cc: Jan Kara
Cc: Linus Torvalds
Cc: Luca Abeni
Cc: Mel Gorman
Cc: Mike Galbraith
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Petr Mladek
Cc: Rik van Riel
Cc: Sergey Senozhatsky
Cc: Thomas Gleixner
Cc: Wanpeng Li
Cc: Yuyang Du
Link: http://lkml.kernel.org/r/20160921133813.31976-5-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar -
CONFIG_VIRT_CPU_ACCOUNTING_NATIVE=y used to accumulate user time and
account it on ticks and context switches only through the
vtime_account_user() function.Now this model has been generalized on the 3 archs for all kind of
cputime (system, irq, ...) and all the cputime flushing happens under
vtime_account_user().So let's rename this function to better reflect its new role.
Signed-off-by: Frederic Weisbecker
Acked-by: Thomas Gleixner
Acked-by: Martin Schwidefsky
Cc: Benjamin Herrenschmidt
Cc: Christian Borntraeger
Cc: Fenghua Yu
Cc: Heiko Carstens
Cc: Linus Torvalds
Cc: Michael Ellerman
Cc: Paul Mackerras
Cc: Peter Zijlstra
Cc: Rik van Riel
Cc: Stanislaw Gruszka
Cc: Tony Luck
Cc: Wanpeng Li
Link: http://lkml.kernel.org/r/1483636310-6557-11-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar -
The account_system_time() function is called with a cputime that
occurred while running in the kernel. The function detects which
context the CPU is currently running in and accounts the time to
the correct bucket. This forces the arch code to account the
cputime for hardirq and softirq immediately.Such accounting function can be costly and perform unwelcome divisions
and multiplications, among others.The arch code can delay the accounting for system time. For s390
the accounting is done once per timer tick and for each task switch.Signed-off-by: Martin Schwidefsky
Signed-off-by: Frederic Weisbecker
[ Rebase against latest linus tree and move account_system_index_scaled(). ]
Acked-by: Thomas Gleixner
Cc: Benjamin Herrenschmidt
Cc: Christian Borntraeger
Cc: Fenghua Yu
Cc: Heiko Carstens
Cc: Linus Torvalds
Cc: Michael Ellerman
Cc: Paul Mackerras
Cc: Peter Zijlstra
Cc: Rik van Riel
Cc: Stanislaw Gruszka
Cc: Tony Luck
Cc: Wanpeng Li
Link: http://lkml.kernel.org/r/1483636310-6557-10-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar -
Currently CONFIG_VIRT_CPU_ACCOUNTING_NATIVE=y accounts the cputime on
any context boundary: irq entry/exit, guest entry/exit, context switch,
etc...Calling functions such as account_system_time(), account_user_time()
and such can be costly, especially if they are called on many fastpath
such as twice per IRQ. Those functions do more than just accounting to
kcpustat and task cputime. Depending on the config, some subsystems can
perform unpleasant multiplications and divisions, among other things.So lets accumulate the cputime instead and delay the accounting on ticks
and context switches only.Signed-off-by: Frederic Weisbecker
Acked-by: Thomas Gleixner
Cc: Benjamin Herrenschmidt
Cc: Christian Borntraeger
Cc: Fenghua Yu
Cc: Heiko Carstens
Cc: Linus Torvalds
Cc: Martin Schwidefsky
Cc: Michael Ellerman
Cc: Paul Mackerras
Cc: Peter Zijlstra
Cc: Rik van Riel
Cc: Stanislaw Gruszka
Cc: Tony Luck
Cc: Wanpeng Li
Link: http://lkml.kernel.org/r/1483636310-6557-9-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar -
Currently CONFIG_VIRT_CPU_ACCOUNTING_NATIVE=y accounts the cputime on
any context boundary: irq entry/exit, guest entry/exit, context switch,
etc...Calling functions such as account_system_time(), account_user_time()
and such can be costly, especially if they are called on many fastpath
such as twice per IRQ. Those functions do more than just accounting to
kcpustat and task cputime. Depending on the config, some subsystems can
perform unpleasant multiplications and divisions, among other things.So lets accumulate the cputime instead and delay the accounting on ticks
and context switches only.Signed-off-by: Frederic Weisbecker
Acked-by: Thomas Gleixner
Cc: Benjamin Herrenschmidt
Cc: Christian Borntraeger
Cc: Fenghua Yu
Cc: Heiko Carstens
Cc: Linus Torvalds
Cc: Martin Schwidefsky
Cc: Michael Ellerman
Cc: Paul Mackerras
Cc: Peter Zijlstra
Cc: Rik van Riel
Cc: Stanislaw Gruszka
Cc: Tony Luck
Cc: Wanpeng Li
Link: http://lkml.kernel.org/r/1483636310-6557-8-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar -
That in order to gather all cputime accumulation to the same place.
Signed-off-by: Frederic Weisbecker
Acked-by: Thomas Gleixner
Cc: Benjamin Herrenschmidt
Cc: Christian Borntraeger
Cc: Fenghua Yu
Cc: Heiko Carstens
Cc: Linus Torvalds
Cc: Martin Schwidefsky
Cc: Michael Ellerman
Cc: Paul Mackerras
Cc: Peter Zijlstra
Cc: Rik van Riel
Cc: Stanislaw Gruszka
Cc: Tony Luck
Cc: Wanpeng Li
Link: http://lkml.kernel.org/r/1483636310-6557-7-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar -
In order to prepare for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE=y to delay
cputime accounting to the tick, provide finegrained accumulators to
powerpc in order to store the cputime until flushing.While at it, normalize the name of several fields according to common
cputime naming.Signed-off-by: Frederic Weisbecker
Acked-by: Thomas Gleixner
Cc: Benjamin Herrenschmidt
Cc: Christian Borntraeger
Cc: Fenghua Yu
Cc: Heiko Carstens
Cc: Linus Torvalds
Cc: Martin Schwidefsky
Cc: Michael Ellerman
Cc: Paul Mackerras
Cc: Peter Zijlstra
Cc: Rik van Riel
Cc: Stanislaw Gruszka
Cc: Tony Luck
Cc: Wanpeng Li
Link: http://lkml.kernel.org/r/1483636310-6557-6-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar -
In order to prepare for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE=y to delay
cputime accounting to the tick, let's allow archs to account cputime
directly to gtime.Signed-off-by: Frederic Weisbecker
Acked-by: Thomas Gleixner
Cc: Benjamin Herrenschmidt
Cc: Christian Borntraeger
Cc: Fenghua Yu
Cc: Heiko Carstens
Cc: Linus Torvalds
Cc: Martin Schwidefsky
Cc: Michael Ellerman
Cc: Paul Mackerras
Cc: Peter Zijlstra
Cc: Rik van Riel
Cc: Stanislaw Gruszka
Cc: Tony Luck
Cc: Wanpeng Li
Link: http://lkml.kernel.org/r/1483636310-6557-5-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar -
In order to prepare for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE=y to delay
cputime accounting to the tick, let's provide APIs to account system
time to precise contexts: hardirq, softirq, pure system, ...Inspired-by: Martin Schwidefsky
Signed-off-by: Frederic Weisbecker
Acked-by: Thomas Gleixner
Cc: Benjamin Herrenschmidt
Cc: Christian Borntraeger
Cc: Fenghua Yu
Cc: Heiko Carstens
Cc: Linus Torvalds
Cc: Martin Schwidefsky
Cc: Michael Ellerman
Cc: Paul Mackerras
Cc: Peter Zijlstra
Cc: Rik van Riel
Cc: Stanislaw Gruszka
Cc: Tony Luck
Cc: Wanpeng Li
Link: http://lkml.kernel.org/r/1483636310-6557-4-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar -
On task switch we must initialize the current cputime of the next task
using the value of the previous task which got freshly updated.But we are confusing that with doing the opposite, which should result
in incorrect cputime accounting.Signed-off-by: Frederic Weisbecker
Acked-by: Thomas Gleixner
Cc: Benjamin Herrenschmidt
Cc: Christian Borntraeger
Cc: Fenghua Yu
Cc: Heiko Carstens
Cc: Linus Torvalds
Cc: Martin Schwidefsky
Cc: Michael Ellerman
Cc: Paul Mackerras
Cc: Peter Zijlstra
Cc: Rik van Riel
Cc: Stanislaw Gruszka
Cc: Tony Luck
Cc: Wanpeng Li
Link: http://lkml.kernel.org/r/1483636310-6557-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar -
On context switch with powerpc32, the cputime is accumulated in the
thread_info struct. So the switching-in task must move forward its
start time snapshot to the current time in order to later compute the
delta spent in system mode.This is what we do for the normal cputime by initializing the starttime
field to the value of the previous task's starttime which got freshly
updated.But we are missing the update of the scaled cputime start time. As a
result we may be accounting too much scaled cputime later.Fix this by initializing the scaled cputime the same way we do for
normal cputime.Signed-off-by: Frederic Weisbecker
Acked-by: Thomas Gleixner
Cc: Benjamin Herrenschmidt
Cc: Christian Borntraeger
Cc: Fenghua Yu
Cc: Heiko Carstens
Cc: Linus Torvalds
Cc: Martin Schwidefsky
Cc: Michael Ellerman
Cc: Paul Mackerras
Cc: Peter Zijlstra
Cc: Rik van Riel
Cc: Stanislaw Gruszka
Cc: Tony Luck
Cc: Wanpeng Li
Link: http://lkml.kernel.org/r/1483636310-6557-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar -
Pull btrfs fixes from Chris Mason:
"These are all over the place.The tracepoint part of the pull fixes a crash and adds a little more
information to two tracepoints, while the rest are good old fashioned
fixes"* 'for-linus-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
btrfs: make tracepoint format strings more compact
Btrfs: add truncated_len for ordered extent tracepoints
Btrfs: add 'inode' for extent map tracepoint
btrfs: fix crash when tracepoint arguments are freed by wq callbacks
Btrfs: adjust outstanding_extents counter properly when dio write is split
Btrfs: fix lockdep warning about log_mutex
Btrfs: use down_read_nested to make lockdep silent
btrfs: fix locking when we put back a delayed ref that's too new
btrfs: fix error handling when run_delayed_extent_op fails
btrfs: return the actual error value from from btrfs_uuid_tree_iterate -
Pull ceph fixes from Ilya Dryomov:
"Two small fixups for the filesystem changes that went into this merge
window"* tag 'ceph-for-4.10-rc4' of git://github.com/ceph/ceph-client:
ceph: fix get_oldest_context()
ceph: fix mds cluster availability check -
Pull VFIO fixes from Alex Williamson:
- Cleanups and bug fixes for the mtty sample driver (Dan Carpenter)
- Export and make use of has_capability() to fix incorrect use of
ns_capable() for testing task capabilities (Jike Song)* tag 'vfio-v4.10-rc4' of git://github.com/awilliam/linux-vfio:
vfio/type1: Remove pid_namespace.h include
vfio iommu type1: fix the testing of capability for remote task
capability: export has_capability
vfio-mdev: remove some dead code
vfio-mdev: buffer overflow in ioctl()
vfio-mdev: return -EFAULT if copy_to_user() fails -
Pull KVM fixes from Paolo Bonzini:
- fix for module unload vs deferred jump labels (note: there might be
other buggy modules!)- two NULL pointer dereferences from syzkaller
- also syzkaller: fix emulation of fxsave/fxrstor/sgdt/sidt, problem
made worse during this merge window, "just" kernel memory leak on
releases- fix emulation of "mov ss" - somewhat serious on AMD, less so on Intel
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: x86: fix emulation of "MOV SS, null selector"
KVM: x86: fix NULL deref in vcpu_scan_ioapic
KVM: eventfd: fix NULL deref irqbypass consumer
KVM: x86: Introduce segmented_write_std
KVM: x86: flush pending lapic jump label updates on module unload
jump_labels: API for flushing deferred jump label updates -
Pull arm64 fixes from Catalin Marinas:
- Fix huge_ptep_set_access_flags() to return "changed" when any of the
ptes in the contiguous range is changed, not just the last one- Fix the adr_l assembly macro to work in modules under KASLR
* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
arm64: assembler: make adr_l work in modules under KASLR
arm64: hugetlb: fix the wrong return value for huge_ptep_set_access_flags -
Pull SCSI fixes from James Bottomley:
"The major fix is the bfa firmware, since the latest 10Gb cards fail
probing with the current firmware.The rest is a set of minor fixes: one missed Kconfig dependency
causing randconfig failures, a missed error return on an error leg, a
change for how multiqueue waits on a blocked device and a don't reset
while in reset fix"* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
scsi: bfa: Increase requested firmware version to 3.2.5.1
scsi: snic: Return error code on memory allocation failure
scsi: fnic: Avoid sending reset to firmware when another reset is in progress
scsi: qedi: fix build, depends on UIO
scsi: scsi-mq: Wait for .queue_rq() if necessary -
Pull input updates from Dmitry Torokhov:
"Small driver fixups"* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
Input: elants_i2c - avoid divide by 0 errors on bad touchscreen data
Input: adxl34x - make it enumerable in ACPI environment
Input: ALPS - fix TrackStick Y axis handling for SS5 hardware
Input: synaptics-rmi4 - fix F03 build error when serio is module
Input: xpad - use correct product id for x360w controllers
Input: synaptics_i2c - change msleep to usleep_range for small msecs
Input: i8042 - add Pegatron touchpad to noloop table
Input: joydev - remove unused linux/miscdevice.h include
