The Meta idle function jumps into the interrupt handler which
efficiently blocks waiting for the next interrupt when it reads the
interrupt status register (TXSTATI). No other (polling) idle functions
can be used, therefore TIF_POLLING_NRFLAG is unnecessary, so lets remove
it.
Peter Zijlstra said:
> Most archs have (x86) hlt or (arm) wfi like idle instructions, and if
> that is your only possible idle function, you'll require the interrupt
> to wake up and there's really no point to having the POLLING bit.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/536CEB7E.9080007@imgtec.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Because mwait_idle_with_hints() gets called from !idle context it must
call current_clr_polling(). This however means that resched_task() is
very likely to send an IPI even when we were polling:
CPU0 CPU1
if (current_set_polling_and_test())
goto out;
__monitor(&ti->flags);
if (!need_resched())
__mwait(eax, ecx);
set_tsk_need_resched(p);
smp_mb();
out:
current_clr_polling();
if (!tsk_is_polling(p))
smp_send_reschedule(cpu);
So while it is correct (extra IPIs aren't a problem, whereas a missed
IPI would be) it is a performance problem (for some).
Avoid this issue by using fetch_or() to atomically set NEED_RESCHED
and test if POLLING_NRFLAG is set.
Since a CPU stuck in mwait is unlikely to modify the flags word,
contention on the cmpxchg is unlikely and thus we should mostly
succeed in a single go.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-kf5suce6njh5xf5d3od13rr0@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Standardize the idle polling indicator to TIF_POLLING_NRFLAG such that
both TIF_NEED_RESCHED and TIF_POLLING_NRFLAG are in the same word.
This will allow us, using fetch_or(), to both set NEED_RESCHED and
check for POLLING_NRFLAG in a single operation and avoid pointless
wakeups.
Changing from the non-atomic thread_info::status flags to the atomic
thread_info::flags shouldn't be a big issue since most polling state
changes were followed/preceded by a full memory barrier anyway.
Also, fix up the apm_32 idle function, clearly that was forgotten in
the last conversion. The default idle state is !POLLING so just kill
the lot.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Link: http://lkml.kernel.org/n/tip-7yksmqtlv4nfowmlqr1rifoi@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Standardize the idle polling indicator to TIF_POLLING_NRFLAG such that
both TIF_NEED_RESCHED and TIF_POLLING_NRFLAG are in the same word.
This will allow us, using fetch_or(), to both set NEED_RESCHED and
check for POLLING_NRFLAG in a single operation and avoid pointless
wakeups.
Changing from the non-atomic thread_info::status flags to the atomic
thread_info::flags shouldn't be a big issue since most polling state
changes were followed/preceded by a full memory barrier anyway.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-35zzwlvwr7cp8xj196y10yyx@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Setting the numa_preferred_node for a task in task_numa_migrate
does nothing on a 2-node system. Either we migrate to the node
that already was our preferred node, or we stay where we were.
On a 4-node system, it can slightly decrease overhead, by not
calling the NUMA code as much. Since every node tends to be
directly connected to every other node, running on the wrong
node for a while does not do much damage.
However, on an 8 node system, there are far more bad nodes
than there are good ones, and pretending that a second choice
is actually the preferred node can greatly delay, or even
prevent, a workload from converging.
The only time we can safely pretend that a second choice
node is the preferred node is when the task is part of a
workload that spans multiple NUMA nodes.
Signed-off-by: Rik van Riel <riel@redhat.com>
Tested-by: Vinod Chegu <chegu_vinod@hp.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1397235629-16328-4-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The NUMA code is smart enough to distribute the memory of workloads
that span multiple NUMA nodes across those NUMA nodes.
However, it still has a pretty high scan rate for such workloads,
because any memory that is left on a node other than the node of
the CPU that faulted on the memory is counted as non-local, which
causes the scan rate to go up.
Counting the memory on any node where the task's numa group is
actively running as local, allows the scan rate to slow down
once the application is settled in.
This should reduce the overhead of the automatic NUMA placement
code, when a workload spans multiple NUMA nodes.
Signed-off-by: Rik van Riel <riel@redhat.com>
Tested-by: Vinod Chegu <chegu_vinod@hp.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1397235629-16328-2-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tim wrote:
"The current code will call pick_next_task_fair a second time in the
slow path if we did not pull any task in our first try. This is
really unnecessary as we already know no task can be pulled and it
doubles the delay for the cpu to enter idle.
We instrumented some network workloads and that saw that
pick_next_task_fair is frequently called twice before a cpu enters
idle. The call to pick_next_task_fair can add non trivial latency as
it calls load_balance which runs find_busiest_group on an hierarchy of
sched domains spanning the cpus for a large system. For some 4 socket
systems, we saw almost 0.25 msec spent per call of pick_next_task_fair
before a cpu can be idled."
Optimize the second call away for the common case and document the
dependency.
Reported-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Len Brown <len.brown@intel.com>
Link: http://lkml.kernel.org/r/20140424100047.GP11096@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The check at the beginning of cpupri_find() makes sure that the task_pri
variable does not exceed the cp->pri_to_cpu array length. But that length
is CPUPRI_NR_PRIORITIES not MAX_RT_PRIO, where it will miss the last two
priorities in that array.
As task_pri is computed from convert_prio() which should never be bigger
than CPUPRI_NR_PRIORITIES, if the check should cause a panic if it is
hit.
Reported-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1397015410.5212.13.camel@marge.simpson.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
yield_task_dl() is broken:
o it forces current to be throttled setting its runtime to zero;
o it sets current's dl_se->dl_new to one, expecting that dl_task_timer()
will queue it back with proper parameters at replenish time.
Unfortunately, dl_task_timer() has this check at the very beginning:
if (!dl_task(p) || dl_se->dl_new)
goto unlock;
So, it just bails out and the task is never replenished. It actually
yielded forever.
To fix this, introduce a new flag indicating that the task properly yielded
the CPU before its current runtime expired. While this is a little overdoing
at the moment, the flag would be useful in the future to discriminate between
"good" jobs (of which remaining runtime could be reclaimed, i.e. recycled)
and "bad" jobs (for which dl_throttled task has been set) that needed to be
stopped.
Reported-by: yjay.kim <yjay.kim@lge.com>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140429103953.e68eba1b2ac3309214e3dc5a@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Russell reported, that irqtime_account_idle_ticks() takes ages due to:
for (i = 0; i < ticks; i++)
irqtime_account_process_tick(current, 0, rq);
It's sad, that this code was written way _AFTER_ the NOHZ idle
functionality was available. I charge myself guitly for not paying
attention when that crap got merged with commit abb74cefa ("sched:
Export ns irqtimes through /proc/stat")
So instead of looping nr_ticks times just apply the whole thing at
once.
As a side note: The whole cputime_t vs. u64 business in that context
wants to be cleaned up as well. There is no point in having all these
back and forth conversions. Lets standardise on u64 nsec for all
kernel internal accounting and be done with it. Everything else does
not make sense at all for fine grained accounting. Frederic, can you
please take care of that?
Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Venkatesh Pallipadi <venki@google.com>
Cc: Shaun Ruffell <sruffell@digium.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1405022307000.6261@ionos.tec.linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When 'flags' argument to sched_{set,get}attr() syscalls were
added in:
6d35ab4809 ("sched: Add 'flags' argument to sched_{set,get}attr() syscalls")
no description for 'flags' was added. It causes the following warnings on "make htmldocs":
Warning(/kernel/sched/core.c:3645): No description found for parameter 'flags'
Warning(/kernel/sched/core.c:3789): No description found for parameter 'flags'
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Cc: peterz@infradead.org
Link: http://lkml.kernel.org/r/1397753955-2914-1-git-send-email-standby24x7@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull gpio fixes from Linus Walleij:
"A small batch of GPIO fixes for the v3.15 series. I expect more to
come in but I'm a bit behind on mail, might as well get these to you
right now:
- Change a crucial semantic ordering in the GPIO irqchip helpers
- Fix two nasty regressions in the ACPI gpiolib extensions"
* tag 'gpio-v3.15-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
gpio / ACPI: Prevent potential wrap of GPIO value on OpRegion read
gpio / ACPI: Don't crash on NULL chip->dev
gpio: set data first, then chip and handler
Pull x86 vdso fix from Peter Anvin:
"This is a single build fix for building with gold as opposed to GNU
ld. It got queued up separately and was expected to be pushed during
the merge window, but it got left behind"
* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, vdso: Make the vdso linker script compatible with Gold
Pull ext4 fixes from Ted Ts'o:
"These are regression and bug fixes for ext4.
We had a number of new features in ext4 during this merge window
(ZERO_RANGE and COLLAPSE_RANGE fallocate modes, renameat, etc.) so
there were many more regression and bug fixes this time around. It
didn't help that xfstests hadn't been fully updated to fully stress
test COLLAPSE_RANGE until after -rc1"
* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (31 commits)
ext4: disable COLLAPSE_RANGE for bigalloc
ext4: fix COLLAPSE_RANGE failure with 1KB block size
ext4: use EINVAL if not a regular file in ext4_collapse_range()
ext4: enforce we are operating on a regular file in ext4_zero_range()
ext4: fix extent merging in ext4_ext_shift_path_extents()
ext4: discard preallocations after removing space
ext4: no need to truncate pagecache twice in collapse range
ext4: fix removing status extents in ext4_collapse_range()
ext4: use filemap_write_and_wait_range() correctly in collapse range
ext4: use truncate_pagecache() in collapse range
ext4: remove temporary shim used to merge COLLAPSE_RANGE and ZERO_RANGE
ext4: fix ext4_count_free_clusters() with EXT4FS_DEBUG and bigalloc enabled
ext4: always check ext4_ext_find_extent result
ext4: fix error handling in ext4_ext_shift_extents
ext4: silence sparse check warning for function ext4_trim_extent
ext4: COLLAPSE_RANGE only works on extent-based files
ext4: fix byte order problems introduced by the COLLAPSE_RANGE patches
ext4: use i_size_read in ext4_unaligned_aio()
fs: disallow all fallocate operation on active swapfile
fs: move falloc collapse range check into the filesystem methods
...
The reverse case of this race (you must msync before read) is
well known. This is the not so common one.
It can be triggered only on systems which do a lot of task
switching and only at UML startup. If you are starting 200+ UMLs
~ 0.5% will always die without this fix.
Signed-off-by: Anton Ivanov <antivano@cisco.com>
[rw: minor whitespace fixes]
Signed-off-by: Richard Weinberger <richard@nod.at>
UML does not handle sigpipe. As a result when running it under
expect or redirecting the IO from the console to an external program
it will crash if the program stops or exits.
Signed-off-by: Anton Ivanov <antivano@cisco.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Inferring the mount hierarchy correctly from /proc/mounts is hard when MS_MOVE
may have been used, and the previous code did it wrongly. This change simplifies
the logic to only require that /dev/shm be _on_ tmpfs (which can be checked
trivially with statfs) rather than that it be a _mountpoint_ of tmpfs, since
there isn't a compelling reason to be that strict. We also now check for tmpfs
on whatever directory we ultimately use so that the user is better informed.
This change also moves the more standard TMPDIR environment variable check ahead
of the others.
Applies to 3.12.
Signed-off-by: Tristan Schmelcher <tschmelcher@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Pull slave-dmaengine fixes from Vinod Koul:
"Back from long weekend here in India and now the time to send fixes
for slave dmaengine.
- Dan's fix of sirf xlate code
- Jean's fix for timberland
- edma fixes by Sekhar for SG handling and Yuan for changing init
call"
* 'fixes' of git://git.infradead.org/users/vkoul/slave-dma:
dma: fix eDMA driver as a subsys_initcall
dmaengine: sirf: off by one in of_dma_sirfsoc_xlate()
platform: Fix timberdale dependencies
dma: edma: fix incorrect SG list handling
Pull iommu fixes from Joerg Roedel:
"Fixes for regressions:
- fix wrong IOMMU enumeration causing some SCSI device drivers
initialization failures
- ARM-SMMU fixes for a panic condition and a wrong return value"
* tag 'iommu-fixes-v3.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
iommu/arm-smmu: fix panic in arm_smmu_alloc_init_pte
iommu/arm-smmu: Return 0 on unmap failure
iommu/vt-d: fix bug in matching PCI devices with DRHD/RMRR descriptors
iommu/vt-d: Fix get_domain_for_dev() handling of upstream PCIe bridges
iommu/vt-d: fix memory leakage caused by commit ea8ea46
Pull perf/urgent fixes from Jiri Olsa:
User visible changes:
* Adjust symbols in VDSO to properly resolve its function names (Vladimir Nikulichev)
* Improve error reporting for record session failure (Adrien BAK)
* Fix 'Min time' counting in report command (Alexander Yarygin)
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In the current version, when using perf record, if something goes
wrong in tools/perf/builtin-record.c:375
session = perf_session__new(file, false, NULL);
The error message:
"Not enough memory for reading per file header"
is issued. This error message seems to be outdated and is not very
helpful. This patch proposes to replace this error message by
"Perf session creation failed"
I believe this issue has been brought to lkml:
https://lkml.org/lkml/2014/2/24/458
although this patch only tackles a (small) part of the issue.
Additionnaly, this patch improves error reporting in
tools/perf/util/data.c open_file_write.
Currently, if the call to open fails, the user is unaware of it.
This patch logs the error, before returning the error code to
the caller.
Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Adrien BAK <adrien.bak@metascale.org>
Link: http://lkml.kernel.org/r/1397786443.3093.4.camel@beast
[ Reorganize the changelog into paragraphs ]
[ Added empty line after fd declaration in open_file_write ]
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
pert-report doesn't resolve function names in VDSO:
$ perf report --stdio -g flat,0.0,15,callee --sort pid
...
8.76%
0x7fff6b1fe861
__gettimeofday
ACE_OS::gettimeofday()
...
In this case symbol values should be adjusted the same way as for executables,
relocatable objects and prelinked libraries.
After fix:
$ perf report --stdio -g flat,0.0,15,callee --sort pid
...
8.76%
__vdso_gettimeofday
__gettimeofday
ACE_OS::gettimeofday()
Signed-off-by: Vladimir Nikulichev <nvs@tbricks.com>
Tested-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Link: http://lkml.kernel.org/r/969812.163009436-sendEmail@nvs
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Every event in the perf-kvm has a 'stats' structure, which contains
max/min/average/etc times of handling this event.
The problem is that the 'perf-kvm stat report' command always shows
that 'min time' is 0us for every event. Example:
# perf kvm stat report
Analyze events for all VCPUs:
VM-EXIT Samples Samples% Time% Min Time Max Time Avg time
[..]
0xB2 MSCH 12 0.07% 0.00% 0us 8us 7.31us ( +- 2.11% )
0xB2 CHSC 12 0.07% 0.00% 0us 18us 9.39us ( +- 9.49% )
0xB2 STPX 8 0.05% 0.00% 0us 2us 1.88us ( +- 7.18% )
0xB2 STSI 7 0.04% 0.00% 0us 44us 16.49us ( +- 38.20% )
[..]
This happens because the 'stats' structure is not initialized and
stats->min equals to 0. Lets initialize the structure for every
event after its allocation using init_stats() function. This initializes
stats->min to -1 and makes 'Min time' statistics counting work:
# perf kvm stat report
Analyze events for all VCPUs:
VM-EXIT Samples Samples% Time% Min Time Max Time Avg time
[..]
0xB2 MSCH 12 0.07% 0.00% 6us 8us 7.31us ( +- 2.11% )
0xB2 CHSC 12 0.07% 0.00% 7us 18us 9.39us ( +- 9.49% )
0xB2 STPX 8 0.05% 0.00% 1us 2us 1.88us ( +- 7.18% )
0xB2 STSI 7 0.04% 0.00% 1us 44us 16.49us ( +- 38.20% )
[..]
Signed-off-by: Alexander Yarygin <yarygin@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Link: http://lkml.kernel.org/r/1397053319-2130-3-git-send-email-borntraeger@de.ibm.com
[ Fixing the perf examples changelog output ]
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Once COLLAPSE RANGE is be disable for ext4 with bigalloc feature till finding
root-cause of problem. It will be enable with fixing that regression of
xfstest(generic 075 and 091) again.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Ashish Sangwan <a.sangwan@samsung.com>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
When formatting with 1KB or 2KB(not aligned with PAGE SIZE) block
size, xfstests generic/075 and 091 are failing. The offset supplied to
function truncate_pagecache_range is block size aligned. In this
function start offset is re-aligned to PAGE_SIZE by rounding_up to the
next page boundary. Due to this rounding up, old data remains in the
page cache when blocksize is less than page size and start offset is
not aligned with page size. In case of collapse range, we need to
align start offset to page size boundary by doing a round down
operation instead of round up.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Ashish Sangwan <a.sangwan@samsung.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Pull x86 fix from Ingo Molnar:
"This fixes the preemption-count imbalance crash reported by Owen
Kibel"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/mce: Fix CMCI preemption bugs
