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linux-2.6/kernel
Peter Zijlstra 92f6a5e37a sched: Do less agressive buddy clearing
Yanmin reported a hackbench regression due to:

 > commit de69a80be3
 > Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
 > Date:   Thu Sep 17 09:01:20 2009 +0200
 >
 >     sched: Stop buddies from hogging the system

I really liked de69a80b, and it affecting hackbench shows I wasn't
crazy ;-)

So hackbench is a multi-cast, with one sender spraying multiple
receivers, who in their turn don't spray back.

This would be exactly the scenario that patch 'cures'. Previously
we would not clear the last buddy after running the next task,
allowing the sender to get back to work sooner than it otherwise
ought to have been, increasing latencies for other tasks.

Now, since those receivers don't poke back, they don't enforce the
buddy relation, which means there's nothing to re-elect the sender.

Cure this by less agressively clearing the buddy stats. Only clear
buddies when they were not chosen. It should still avoid a buddy
sticking around long after its served its time.

Reported-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Mike Galbraith <efault@gmx.de>
LKML-Reference: <1255084986.8802.46.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-10-14 15:02:34 +02:00
..
gcov microblaze: Enable GCOV_PROFILE_ALL 2009-09-21 14:29:21 +02:00
irq Merge branch 'irq-threaded-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-11 13:21:31 -07:00
power headers: utsname.h redux 2009-09-23 18:13:10 -07:00
time NOHZ: update idle state also when NOHZ is inactive 2009-10-07 13:05:05 +02:00
trace Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-10-08 12:06:09 -07:00
.gitignore
Kconfig.freezer
Kconfig.hz
Kconfig.preempt
Makefile cgroups: move the cgroup debug subsys into cgroup.c to access internal state 2009-09-24 07:20:57 -07:00
acct.c bsdacct: switch credentials for writing to the accounting file 2009-08-24 11:33:40 +10:00
async.c async: Fix lack of boot-time console due to insufficient synchronization 2009-06-08 12:31:53 -07:00
audit.c Audit: send signal info if selinux is disabled 2009-09-24 03:50:26 -04:00
audit.h Fix rule eviction order for AUDIT_DIR 2009-06-24 00:02:38 -04:00
audit_tree.c Fix rule eviction order for AUDIT_DIR 2009-06-24 00:02:38 -04:00
audit_watch.c Audit: reorganize struct audit_watch to save 8 bytes 2009-09-24 03:50:25 -04:00
auditfilter.c Audit: clean up all op= output to include string quoting 2009-06-24 00:00:52 -04:00
auditsc.c Audit: rearrange audit_context to save 16 bytes per struct 2009-09-24 03:50:26 -04:00
backtracetest.c
bounds.c
capability.c
cgroup.c cgroup: catch bad css refcnt at css_put 2009-10-01 16:11:12 -07:00
cgroup_freezer.c cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time 2009-09-24 07:20:58 -07:00
compat.c signals: implement sys_rt_tgsigqueueinfo 2009-04-30 19:24:24 +02:00
configs.c
cpu.c Merge branch 'x86-pat-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-15 09:19:38 -07:00
cpuset.c cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time 2009-09-24 07:20:58 -07:00
cred-internals.h
cred.c creds_are_invalid() needs to be exported for use by modules: 2009-09-23 11:02:26 -07:00
delayacct.c headers: taskstats_kern.h trim 2009-09-18 09:48:52 -07:00
dma.c
exec_domain.c Get rid of indirect include of fs_struct.h 2009-03-31 23:00:27 -04:00
exit.c Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-10-08 12:16:35 -07:00
extable.c Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-04-05 11:04:19 -07:00
fork.c Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-10-08 12:16:35 -07:00
freezer.c sched: fix nr_uninterruptible accounting of frozen tasks really 2009-07-18 14:19:53 +02:00
futex.c Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-10-08 12:16:35 -07:00
futex_compat.c futex: Fix compat_futex to be same as futex for REQUEUE_PI 2009-08-10 15:41:12 +02:00
groups.c groups: move code to kernel/groups.c 2009-06-16 19:47:48 -07:00
hrtimer.c Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-10-05 12:04:16 -07:00
hung_task.c sysctl: remove "struct file *" argument of ->proc_handler 2009-09-24 07:21:04 -07:00
itimer.c itimers: Add tracepoints for itimer 2009-08-29 14:10:07 +02:00
kallsyms.c kallsyms: use new arch_is_kernel_text() 2009-09-23 07:39:30 -07:00
kexec.c kexec: fix omitting offset in extended crashkernel syntax 2009-07-29 19:10:34 -07:00
kfifo.c kfifo: Use "const" definitions 2009-09-19 13:13:17 -07:00
kgdb.c sysrq, intel_fb: fix sysrq g collision 2009-05-15 07:56:24 -05:00
kmod.c Revert "kmod: fix race in usermodehelper code" 2009-09-23 18:12:10 -07:00
kprobes.c const: constify remaining file_operations 2009-10-01 16:11:11 -07:00
ksysfs.c
kthread.c sched: Keep kthreads at default priority 2009-09-09 17:30:06 +02:00
latencytop.c
lockdep.c lockdep: use new arch_is_kernel_data() 2009-09-23 07:39:30 -07:00
lockdep_internals.h lockdep: BFS cleanup 2009-07-24 10:53:29 +02:00
lockdep_proc.c seq_file: constify seq_operations 2009-09-23 07:39:29 -07:00
lockdep_states.h
module.c module: fix up CONFIG_KALLSYMS=n build. 2009-10-01 16:11:11 -07:00
mutex-debug.c
mutex-debug.h
mutex.c Merge branch 'linus' into perfcounters/core 2009-06-11 17:55:42 +02:00
mutex.h
notifier.c
ns_cgroup.c cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time 2009-09-24 07:20:58 -07:00
nsproxy.c nsproxy: extract create_nsproxy() 2009-06-18 13:03:56 -07:00
panic.c Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-10-08 12:16:35 -07:00
params.c param: allow whitespace as kernel parameter separator 2009-09-25 00:32:58 +09:30
perf_event.c perf_event: Provide vmalloc() based mmap() backing 2009-10-06 14:21:50 +02:00
pid.c mm: also use alloc_large_system_hash() for the PID hash table 2009-09-22 07:17:38 -07:00
pid_namespace.c pidns: deny CLONE_PARENT|CLONE_NEWPID combination 2009-09-24 07:21:04 -07:00
pm_qos_params.c
posix-cpu-timers.c itimers: Add tracepoints for itimer 2009-08-29 14:10:07 +02:00
posix-timers.c time: Introduce CLOCK_REALTIME_COARSE 2009-08-21 21:43:46 +02:00
printk.c printk: add printk_delay to make messages readable for some scenarios 2009-09-23 07:39:28 -07:00
profile.c kernel/profile.c: Switch /proc/irq/prof_cpu_mask to seq_file 2009-09-20 20:15:40 +02:00
ptrace.c ptrace: __ptrace_detach: do __wake_up_parent() if we reap the tracee 2009-09-24 07:20:59 -07:00
rcupdate.c rcu: Move rcu_barrier() to rcutree 2009-10-07 08:11:20 +02:00
rcutorture.c rcu: Clean up code to address Ingo's checkpatch feedback 2009-09-23 19:46:30 +02:00
rcutree.c rcu: Place root rcu_node structure in separate lockdep class 2009-10-07 08:11:21 +02:00
rcutree.h rcu: Make hot-unplugged CPU relinquish its own RCU callbacks 2009-10-07 08:11:20 +02:00
rcutree_plugin.h rcu: Make hot-unplugged CPU relinquish its own RCU callbacks 2009-10-07 08:11:20 +02:00
rcutree_trace.c rcu: Make hot-unplugged CPU relinquish its own RCU callbacks 2009-10-07 08:11:20 +02:00
relay.c const: mark struct vm_struct_operations 2009-09-27 11:39:25 -07:00
res_counter.c memcg: some modification to softlimit under hierarchical memory reclaim. 2009-10-01 16:11:13 -07:00
resource.c walk system ram range 2009-09-23 07:39:41 -07:00
rtmutex-debug.c
rtmutex-debug.h
rtmutex-tester.c
rtmutex.c rtmutex: Avoid deadlock in rt_mutex_start_proxy_lock() 2009-08-06 05:50:21 +02:00
rtmutex.h
rtmutex_common.h rt_mutex: add proxy lock routines 2009-04-06 11:14:02 +02:00
rwsem.c
sched.c sched: Fix missing kernel-doc notation 2009-10-12 10:50:06 +02:00
sched_clock.c sched_clock: Fix atomicity/continuity bug by using cmpxchg64() 2009-09-30 22:56:10 +02:00
sched_cpupri.c sched: Add new prio to cpupri before removing old prio 2009-08-02 14:26:09 +02:00
sched_cpupri.h cpumask: remove cpumask_t from core 2009-03-30 22:05:17 +10:30
sched_debug.c sched: Add new wakeup preemption mode: WAKEUP_RUNNING 2009-09-17 10:17:25 +02:00
sched_fair.c sched: Do less agressive buddy clearing 2009-10-14 15:02:34 +02:00
sched_features.h sched: Add new wakeup preemption mode: WAKEUP_RUNNING 2009-09-17 10:17:25 +02:00
sched_idletask.c sched: Simplify sys_sched_rr_get_interval() system call 2009-09-21 09:53:55 +02:00
sched_rt.c sched: Simplify sys_sched_rr_get_interval() system call 2009-09-21 09:53:55 +02:00
sched_stats.h sched: remove unused fields from struct rq 2009-03-24 23:16:51 +01:00
seccomp.c
semaphore.c
signal.c signals: inline __fatal_signal_pending 2009-09-24 07:21:01 -07:00
slow-work.c sysctl: remove "struct file *" argument of ->proc_handler 2009-09-24 07:21:04 -07:00
smp.c cpumask: remove arch_send_call_function_ipi 2009-09-24 09:34:47 +09:30
softirq.c softirq: add BLOCK_IOPOLL to softirq_to_name 2009-09-17 15:53:44 -04:00
softlockup.c sysctl: remove "struct file *" argument of ->proc_handler 2009-09-24 07:21:04 -07:00
spinlock.c locking: Allow arch-inlined spinlocks 2009-08-31 18:08:50 +02:00
srcu.c
stacktrace.c
stop_machine.c cpumask: remove cpumask_t from core 2009-03-30 22:05:17 +10:30
sys.c Merge branch 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6 2009-09-24 07:53:22 -07:00
sys_ni.c Merge branch 'master' of /home/davem/src/GIT/linux-2.6/ 2009-09-24 15:13:11 -07:00
sysctl.c Merge branch 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6 2009-09-24 07:53:22 -07:00
sysctl_check.c
taskstats.c genetlink: make netns aware 2009-07-12 14:03:27 -07:00
test_kprobes.c
time.c time: Prevent 32 bit overflow with set_normalized_timespec() 2009-09-15 10:17:30 +02:00
timeconst.pl
timer.c Merge branch 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-23 09:46:15 -07:00
tracepoint.c trivial: fix typo "to to" in multiple files 2009-09-21 15:14:55 +02:00
tsacct.c
uid16.c headers: utsname.h redux 2009-09-23 18:13:10 -07:00
up.c
user.c sched: delayed cleanup of user_struct 2009-06-15 21:30:23 -07:00
user_namespace.c
utsname.c utsns: extract creeate_uts_ns() 2009-06-18 13:03:55 -07:00
utsname_sysctl.c sysctl: remove "struct file *" argument of ->proc_handler 2009-09-24 07:21:04 -07:00
wait.c locking, sched: Give waitqueue spinlocks their own lockdep classes 2009-08-10 14:43:09 +02:00
workqueue.c Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-11 13:23:18 -07:00