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  1. 21 9月, 2009 3 次提交
    • I
      perf: Do the big rename: Performance Counters -> Performance Events · cdd6c482
      由 Ingo Molnar 提交于 
      Bye-bye Performance Counters, welcome Performance Events!

In the past few months the perfcounters subsystem has grown out its
initial role of counting hardware events, and has become (and is
becoming) a much broader generic event enumeration, reporting, logging,
monitoring, analysis facility.

Naming its core object 'perf_counter' and naming the subsystem
'perfcounters' has become more and more of a misnomer. With pending
code like hw-breakpoints support the 'counter' name is less and
less appropriate.

All in one, we've decided to rename the subsystem to 'performance
events' and to propagate this rename through all fields, variables
and API names. (in an ABI compatible fashion)

The word 'event' is also a bit shorter than 'counter' - which makes
it slightly more convenient to write/handle as well.

Thanks goes to Stephane Eranian who first observed this misnomer and
suggested a rename.

User-space tooling and ABI compatibility is not affected - this patch
should be function-invariant. (Also, defconfigs were not touched to
keep the size down.)

This patch has been generated via the following script:

  FILES=$(find * -type f | grep -vE 'oprofile|[^K]config')

  sed -i \
    -e 's/PERF_EVENT_/PERF_RECORD_/g' \
    -e 's/PERF_COUNTER/PERF_EVENT/g' \
    -e 's/perf_counter/perf_event/g' \
    -e 's/nb_counters/nb_events/g' \
    -e 's/swcounter/swevent/g' \
    -e 's/tpcounter_event/tp_event/g' \
    $FILES

  for N in $(find . -name perf_counter.[ch]); do
    M=$(echo $N | sed 's/perf_counter/perf_event/g')
    mv $N $M
  done

  FILES=$(find . -name perf_event.*)

  sed -i \
    -e 's/COUNTER_MASK/REG_MASK/g' \
    -e 's/COUNTER/EVENT/g' \
    -e 's/\<event\>/event_id/g' \
    -e 's/counter/event/g' \
    -e 's/Counter/Event/g' \
    $FILES

... to keep it as correct as possible. This script can also be
used by anyone who has pending perfcounters patches - it converts
a Linux kernel tree over to the new naming. We tried to time this
change to the point in time where the amount of pending patches
is the smallest: the end of the merge window.

Namespace clashes were fixed up in a preparatory patch - and some
stylistic fallout will be fixed up in a subsequent patch.

( NOTE: 'counters' are still the proper terminology when we deal
  with hardware registers - and these sed scripts are a bit
  over-eager in renaming them. I've undone some of that, but
  in case there's something left where 'counter' would be
  better than 'event' we can undo that on an individual basis
  instead of touching an otherwise nicely automated patch. )
Suggested-by: NStephane Eranian <eranian@google.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NPaul Mackerras <paulus@samba.org>
Reviewed-by: NArjan van de Ven <arjan@linux.intel.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <linux-arch@vger.kernel.org>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      cdd6c482
    • P
      sched: Simplify sys_sched_rr_get_interval() system call · 0d721cea
      由 Peter Williams 提交于 
      By removing the need for it to know details of scheduling classes.

This allows PlugSched to define orthogonal scheduling classes.
Signed-off-by: NPeter Williams <pwil3058@bigpond.net.au>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <06d1b89ee15a0eef82d7.1253496713@mudlark.pw.nest>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      0d721cea
    • A
      sched: Fix raciness in runqueue_is_locked() · 89f19f04
      由 Andrew Morton 提交于 
      runqueue_is_locked() is unavoidably racy due to a poor interface design.
It does

	cpu = get_cpu()
	ret = some_perpcu_thing(cpu);
	put_cpu(cpu);
	return ret;

Its return value is unreliable.

Fix.
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <200909191855.n8JItiko022148@imap1.linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      89f19f04
  3. 18 9月, 2009 1 次提交
    • P
      rcu: Simplify rcu_read_unlock_special() quiescent-state accounting · c3422bea
      由 Paul E. McKenney 提交于 
      The earlier approach required two scheduling-clock ticks to note an
preemptable-RCU quiescent state in the situation in which the
scheduling-clock interrupt is unlucky enough to always interrupt an
RCU read-side critical section.

With this change, the quiescent state is instead noted by the
outermost rcu_read_unlock() immediately following the first
scheduling-clock tick, or, alternatively, by the first subsequent
context switch.  Therefore, this change also speeds up grace
periods.
Suggested-by: NJosh Triplett <josh@joshtriplett.org>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: mathieu.desnoyers@polymtl.ca
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
LKML-Reference: <12528585111945-git-send-email->
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      c3422bea
  5. 17 9月, 2009 1 次提交
    • P
      sched: Add new wakeup preemption mode: WAKEUP_RUNNING · ad4b78bb
      由 Peter Zijlstra 提交于 
      Create a new wakeup preemption mode, preempt towards tasks that run
shorter on avg. It sets next buddy to be sure we actually run the task
we preempted for.

Test results:

 root@twins:~# while :; do :; done &
 [1] 6537
 root@twins:~# while :; do :; done &
 [2] 6538
 root@twins:~# while :; do :; done &
 [3] 6539
 root@twins:~# while :; do :; done &
 [4] 6540

 root@twins:/home/peter# ./latt -c4 sleep 4
 Entries: 48 (clients=4)

 Averages:
 ------------------------------
        Max          4750 usec
        Avg           497 usec
        Stdev         737 usec

 root@twins:/home/peter# echo WAKEUP_RUNNING > /debug/sched_features

 root@twins:/home/peter# ./latt -c4 sleep 4
 Entries: 48 (clients=4)

 Averages:
 ------------------------------
        Max            14 usec
        Avg             5 usec
        Stdev           3 usec

Disabled by default - needs more testing.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NMike Galbraith <efault@gmx.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
LKML-Reference: <new-submission>
      ad4b78bb
  7. 16 9月, 2009 1 次提交
  9. 15 9月, 2009 7 次提交
    • P
      sched: Add WF_FORK · a7558e01
      由 Peter Zijlstra 提交于 
      Avoid the cache buddies from biasing the time distribution away
from fork()ers. Normally the next buddy will be the preferred
scheduling target, but this makes fork()s prefer to run the new
child, whereas we prefer to run the parent, since that will
generate more work.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      a7558e01
    • P
      sched: Rename sync arguments · 7d478721
      由 Peter Zijlstra 提交于 
      In order to extend the functions to have more than 1 flag (sync),
rename the argument to flags, and explicitly define a WF_ space for
individual flags.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      7d478721
    • P
      sched: Rename select_task_rq() argument · 0763a660
      由 Peter Zijlstra 提交于 
      In order to be able to rename the sync argument, we need to rename
the current flag argument.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      0763a660
    • P
      x86: sched: Provide arch implementations using aperf/mperf · 47fe38fc
      由 Peter Zijlstra 提交于 
      APERF/MPERF support for cpu_power.

APERF/MPERF is arch defined to be a relative scale of work capacity
per logical cpu, this is assumed to include SMT and Turbo mode.

APERF/MPERF are specified to both reset to 0 when either counter
wraps, which is highly inconvenient, since that'll give a blimp
when that happens. The manual specifies writing 0 to the counters
after each read, but that's 1) too expensive, and 2) destroys the
possibility of sharing these counters with other users, so we live
with the blimp - the other existing user does too.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      47fe38fc
    • P
      sched: Merge select_task_rq_fair() and sched_balance_self() · c88d5910
      由 Peter Zijlstra 提交于 
      The problem with wake_idle() is that is doesn't respect things like
cpu_power, which means it doesn't deal well with SMT nor the recent
RT interaction.

To cure this, it needs to do what sched_balance_self() does, which
leads to the possibility of merging select_task_rq_fair() and
sched_balance_self().

Modify sched_balance_self() to:

  - update_shares() when walking up the domain tree,
    (it only called it for the top domain, but it should
     have done this anyway), which allows us to remove
    this ugly bit from try_to_wake_up().

  - do wake_affine() on the smallest domain that contains
    both this (the waking) and the prev (the wakee) cpu for
    WAKE invocations.

Then use the top-down balance steps it had to replace wake_idle().

This leads to the dissapearance of SD_WAKE_BALANCE and
SD_WAKE_IDLE_FAR, with SD_WAKE_IDLE replaced with SD_BALANCE_WAKE.

SD_WAKE_AFFINE needs SD_BALANCE_WAKE to be effective.

Touch all topology bits to replace the old with new SD flags --
platforms might need re-tuning, enabling SD_BALANCE_WAKE
conditionally on a NUMA distance seems like a good additional
feature, magny-core and small nehalem systems would want this
enabled, systems with slow interconnects would not.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      c88d5910
    • P
      sched: Add TASK_WAKING · e9c84311
      由 Peter Zijlstra 提交于 
      We're going to want to drop rq->lock in try_to_wake_up() for a
longer period of time, however we also want to deal with concurrent
waking of the same task, which is currently handled by holding
rq->lock.

So introduce a new TASK state, namely TASK_WAKING, which indicates
someone is already waking the task (other wakers will fail p->state
& state).

We also keep preemption disabled over the whole ttwu().
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      e9c84311
    • P
      sched: Hook sched_balance_self() into sched_class::select_task_rq() · 5f3edc1b
      由 Peter Zijlstra 提交于 
      Rather ugly patch to fully place the sched_balance_self() code
inside the fair class.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      5f3edc1b
  11. 09 9月, 2009 1 次提交
    • M
      sched: Turn off child_runs_first · 2bba22c5
      由 Mike Galbraith 提交于 
      Set child_runs_first default to off.

It hurts 'optimal' make -j<NR_CPUS> workloads as make jobs
get preempted by child tasks, reducing parallelism.

Note, this patch might make existing races in user
applications more prominent than before - so breakages
might be bisected to this commit.

Child-runs-first is broken on SMP to begin with, and we
already had it off briefly in v2.6.23 so most of the
offenders ought to be fixed. Would be nice not to revert
this commit but fix those apps finally ...
Signed-off-by: NMike Galbraith <efault@gmx.de>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1252486344.28645.18.camel@marge.simson.net>
[ made the sysctl independent of CONFIG_SCHED_DEBUG, in case
  people want to work around broken apps. ]
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      2bba22c5
  13. 04 9月, 2009 4 次提交
  15. 02 9月, 2009 2 次提交
    • D
      KEYS: Add a keyctl to install a process's session keyring on its parent [try #6] · ee18d64c
      由 David Howells 提交于 
      Add a keyctl to install a process's session keyring onto its parent.  This
replaces the parent's session keyring.  Because the COW credential code does
not permit one process to change another process's credentials directly, the
change is deferred until userspace next starts executing again.  Normally this
will be after a wait*() syscall.

To support this, three new security hooks have been provided:
cred_alloc_blank() to allocate unset security creds, cred_transfer() to fill in
the blank security creds and key_session_to_parent() - which asks the LSM if
the process may replace its parent's session keyring.

The replacement may only happen if the process has the same ownership details
as its parent, and the process has LINK permission on the session keyring, and
the session keyring is owned by the process, and the LSM permits it.

Note that this requires alteration to each architecture's notify_resume path.
This has been done for all arches barring blackfin, m68k* and xtensa, all of
which need assembly alteration to support TIF_NOTIFY_RESUME.  This allows the
replacement to be performed at the point the parent process resumes userspace
execution.

This allows the userspace AFS pioctl emulation to fully emulate newpag() and
the VIOCSETTOK and VIOCSETTOK2 pioctls, all of which require the ability to
alter the parent process's PAG membership.  However, since kAFS doesn't use
PAGs per se, but rather dumps the keys into the session keyring, the session
keyring of the parent must be replaced if, for example, VIOCSETTOK is passed
the newpag flag.

This can be tested with the following program:

	#include <stdio.h>
	#include <stdlib.h>
	#include <keyutils.h>

	#define KEYCTL_SESSION_TO_PARENT	18

	#define OSERROR(X, S) do { if ((long)(X) == -1) { perror(S); exit(1); } } while(0)

	int main(int argc, char **argv)
	{
		key_serial_t keyring, key;
		long ret;

		keyring = keyctl_join_session_keyring(argv[1]);
		OSERROR(keyring, "keyctl_join_session_keyring");

		key = add_key("user", "a", "b", 1, keyring);
		OSERROR(key, "add_key");

		ret = keyctl(KEYCTL_SESSION_TO_PARENT);
		OSERROR(ret, "KEYCTL_SESSION_TO_PARENT");

		return 0;
	}

Compiled and linked with -lkeyutils, you should see something like:

	[dhowells@andromeda ~]$ keyctl show
	Session Keyring
	       -3 --alswrv   4043  4043  keyring: _ses
	355907932 --alswrv   4043    -1   \_ keyring: _uid.4043
	[dhowells@andromeda ~]$ /tmp/newpag
	[dhowells@andromeda ~]$ keyctl show
	Session Keyring
	       -3 --alswrv   4043  4043  keyring: _ses
	1055658746 --alswrv   4043  4043   \_ user: a
	[dhowells@andromeda ~]$ /tmp/newpag hello
	[dhowells@andromeda ~]$ keyctl show
	Session Keyring
	       -3 --alswrv   4043  4043  keyring: hello
	340417692 --alswrv   4043  4043   \_ user: a

Where the test program creates a new session keyring, sticks a user key named
'a' into it and then installs it on its parent.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NJames Morris <jmorris@namei.org>
      ee18d64c
    • A
      sched: Provide iowait counters · 8f0dfc34
      由 Arjan van de Ven 提交于 
      For counting how long an application has been waiting for
(disk) IO, there currently is only the HZ sample driven
information available, while for all other counters in this
class, a high resolution version is available via
CONFIG_SCHEDSTATS.

In order to make an improved bootchart tool possible, we also
need a higher resolution version of the iowait time.

This patch below adds this scheduler statistic to the kernel.
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <4A64B813.1080506@linux.intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      8f0dfc34
  17. 29 8月, 2009 2 次提交
  19. 23 8月, 2009 2 次提交
    • P
      rcu: Remove CONFIG_PREEMPT_RCU · 6b3ef48a
      由 Paul E. McKenney 提交于 
      Now that CONFIG_TREE_PREEMPT_RCU is in place, there is no
further need for CONFIG_PREEMPT_RCU.  Remove it, along with
whatever subtle bugs it may (or may not) contain.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: mathieu.desnoyers@polymtl.ca
Cc: josht@linux.vnet.ibm.com
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
LKML-Reference: <125097461396-git-send-email->
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      6b3ef48a
    • P
      rcu: Merge preemptable-RCU functionality into hierarchical RCU · f41d911f
      由 Paul E. McKenney 提交于 
      Create a kernel/rcutree_plugin.h file that contains definitions
for preemptable RCU (or, under the #else branch of the #ifdef,
empty definitions for the classic non-preemptable semantics).
These definitions fit into plugins defined in kernel/rcutree.c
for this purpose.

This variant of preemptable RCU uses a new algorithm whose
read-side expense is roughly that of classic hierarchical RCU
under CONFIG_PREEMPT. This new algorithm's update-side expense
is similar to that of classic hierarchical RCU, and, in absence
of read-side preemption or blocking, is exactly that of classic
hierarchical RCU.  Perhaps more important, this new algorithm
has a much simpler implementation, saving well over 1,000 lines
of code compared to mainline's implementation of preemptable
RCU, which will hopefully be retired in favor of this new
algorithm.

The simplifications are obtained by maintaining per-task
nesting state for running tasks, and using a simple
lock-protected algorithm to handle accounting when tasks block
within RCU read-side critical sections, making use of lessons
learned while creating numerous user-level RCU implementations
over the past 18 months.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: mathieu.desnoyers@polymtl.ca
Cc: josht@linux.vnet.ibm.com
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
LKML-Reference: <12509746134003-git-send-email->
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      f41d911f
  21. 19 8月, 2009 1 次提交
    • K
      mm: revert "oom: move oom_adj value" · 0753ba01
      由 KOSAKI Motohiro 提交于 
      The commit 2ff05b2b (oom: move oom_adj value) moveed the oom_adj value to
the mm_struct.  It was a very good first step for sanitize OOM.

However Paul Menage reported the commit makes regression to his job
scheduler.  Current OOM logic can kill OOM_DISABLED process.

Why? His program has the code of similar to the following.

	...
	set_oom_adj(OOM_DISABLE); /* The job scheduler never killed by oom */
	...
	if (vfork() == 0) {
		set_oom_adj(0); /* Invoked child can be killed */
		execve("foo-bar-cmd");
	}
	....

vfork() parent and child are shared the same mm_struct.  then above
set_oom_adj(0) doesn't only change oom_adj for vfork() child, it's also
change oom_adj for vfork() parent.  Then, vfork() parent (job scheduler)
lost OOM immune and it was killed.

Actually, fork-setting-exec idiom is very frequently used in userland program.
We must not break this assumption.

Then, this patch revert commit 2ff05b2b and related commit.

Reverted commit list
---------------------
- commit 2ff05b2b (oom: move oom_adj value from task_struct to mm_struct)
- commit 4d8b9135 (oom: avoid unnecessary mm locking and scanning for OOM_DISABLE)
- commit 81236810 (oom: only oom kill exiting tasks with attached memory)
- commit 933b787b (mm: copy over oom_adj value at fork time)
Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      0753ba01
  23. 18 8月, 2009 1 次提交
  25. 02 8月, 2009 2 次提交
    • G
      sched: Enhance the pre/post scheduling logic · 3f029d3c
      由 Gregory Haskins 提交于 
      We currently have an explicit "needs_post" vtable method which
returns a stack variable for whether we should later run
post-schedule.  This leads to an awkward exchange of the
variable as it bubbles back up out of the context switch. Peter
Zijlstra observed that this information could be stored in the
run-queue itself instead of handled on the stack.

Therefore, we revert to the method of having context_switch
return void, and update an internal rq->post_schedule variable
when we require further processing.

In addition, we fix a race condition where we try to access
current->sched_class without holding the rq->lock.  This is
technically racy, as the sched-class could change out from
under us.  Instead, we reference the per-rq post_schedule
variable with the runqueue unlocked, but with preemption
disabled to see if we need to reacquire the rq->lock.

Finally, we clean the code up slightly by removing the #ifdef
CONFIG_SMP conditionals from the schedule() call, and implement
some inline helper functions instead.

This patch passes checkpatch, and rt-migrate.
Signed-off-by: NGregory Haskins <ghaskins@novell.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090729150422.17691.55590.stgit@dev.haskins.net>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      3f029d3c
    • F
      sched: Fix cond_resched_lock() in !CONFIG_PREEMPT · 716a4234
      由 Frederic Weisbecker 提交于 
      The might_sleep() test inside cond_resched_lock() assumes the
spinlock is held and then preemption is disabled. This is true
with CONFIG_PREEMPT but the preempt_count() doesn't change
otherwise.

Check by starting from the appropriate preempt offset depending
on the config.
Reported-by: NLi Zefan <lizf@cn.fujitsu.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1248458723-12146-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      716a4234
  27. 18 7月, 2009 4 次提交
  29. 17 7月, 2009 1 次提交
  31. 11 7月, 2009 2 次提交
  33. 01 7月, 2009 1 次提交
  35. 19 6月, 2009 2 次提交
  37. 17 6月, 2009 2 次提交
    • D
      oom: move oom_adj value from task_struct to mm_struct · 2ff05b2b
      由 David Rientjes 提交于 
      The per-task oom_adj value is a characteristic of its mm more than the
task itself since it's not possible to oom kill any thread that shares the
mm.  If a task were to be killed while attached to an mm that could not be
freed because another thread were set to OOM_DISABLE, it would have
needlessly been terminated since there is no potential for future memory
freeing.

This patch moves oomkilladj (now more appropriately named oom_adj) from
struct task_struct to struct mm_struct.  This requires task_lock() on a
task to check its oom_adj value to protect against exec, but it's already
necessary to take the lock when dereferencing the mm to find the total VM
size for the badness heuristic.

This fixes a livelock if the oom killer chooses a task and another thread
sharing the same memory has an oom_adj value of OOM_DISABLE.  This occurs
because oom_kill_task() repeatedly returns 1 and refuses to kill the
chosen task while select_bad_process() will repeatedly choose the same
task during the next retry.

Taking task_lock() in select_bad_process() to check for OOM_DISABLE and in
oom_kill_task() to check for threads sharing the same memory will be
removed in the next patch in this series where it will no longer be
necessary.

Writing to /proc/pid/oom_adj for a kthread will now return -EINVAL since
these threads are immune from oom killing already.  They simply report an
oom_adj value of OOM_DISABLE.

Cc: Nick Piggin <npiggin@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      2ff05b2b
    • M
      cpuset,mm: update tasks' mems_allowed in time · 58568d2a
      由 Miao Xie 提交于 
      Fix allocating page cache/slab object on the unallowed node when memory
spread is set by updating tasks' mems_allowed after its cpuset's mems is
changed.

In order to update tasks' mems_allowed in time, we must modify the code of
memory policy.  Because the memory policy is applied in the process's
context originally.  After applying this patch, one task directly
manipulates anothers mems_allowed, and we use alloc_lock in the
task_struct to protect mems_allowed and memory policy of the task.

But in the fast path, we didn't use lock to protect them, because adding a
lock may lead to performance regression.  But if we don't add a lock,the
task might see no nodes when changing cpuset's mems_allowed to some
non-overlapping set.  In order to avoid it, we set all new allowed nodes,
then clear newly disallowed ones.

[lee.schermerhorn@hp.com:
  The rework of mpol_new() to extract the adjusting of the node mask to
  apply cpuset and mpol flags "context" breaks set_mempolicy() and mbind()
  with MPOL_PREFERRED and a NULL nodemask--i.e., explicit local
  allocation.  Fix this by adding the check for MPOL_PREFERRED and empty
  node mask to mpol_new_mpolicy().

  Remove the now unneeded 'nodes = NULL' from mpol_new().

  Note that mpol_new_mempolicy() is always called with a non-NULL
  'nodes' parameter now that it has been removed from mpol_new().
  Therefore, we don't need to test nodes for NULL before testing it for
  'empty'.  However, just to be extra paranoid, add a VM_BUG_ON() to
  verify this assumption.]
[lee.schermerhorn@hp.com:

  I don't think the function name 'mpol_new_mempolicy' is descriptive
  enough to differentiate it from mpol_new().

  This function applies cpuset set context, usually constraining nodes
  to those allowed by the cpuset.  However, when the 'RELATIVE_NODES flag
  is set, it also translates the nodes.  So I settled on
  'mpol_set_nodemask()', because the comment block for mpol_new() mentions
  that we need to call this function to "set nodes".

  Some additional minor line length, whitespace and typo cleanup.]
Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Paul Menage <menage@google.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      58568d2a