Tim Chen
4486edd12b
sched/fair: Implement fast idling of CPUs when the system is partially loaded ...
When a system is lightly loaded (i.e. no more than 1 job per cpu),
attempt to pull job to a cpu before putting it to idle is unnecessary and
can be skipped. This patch adds an indicator so the scheduler can know
when there's no more than 1 active job is on any CPU in the system to
skip needless job pulls.
On a 4 socket machine with a request/response kind of workload from
clients, we saw about 0.13 msec delay when we go through a full load
balance to try pull job from all the other cpus. While 0.1 msec was
spent on processing the request and generating a response, the 0.13 msec
load balance overhead was actually more than the actual work being done.
This overhead can be skipped much of the time for lightly loaded systems.
With this patch, we tested with a netperf request/response workload that
has the server busy with half the cpus in a 4 socket system. We found
the patch eliminated 75% of the load balance attempts before idling a cpu.
The overhead of setting/clearing the indicator is low as we already gather
the necessary info while we call add_nr_running() and update_sd_lb_stats.()
We switch to full load balance load immediately if any cpu got more than
one job on its run queue in add_nr_running. We'll clear the indicator
to avoid load balance when we detect no cpu's have more than one job
when we scan the work queues in update_sg_lb_stats(). We are aggressive
in turning on the load balance and opportunistic in skipping the load
balance.
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Jason Low <jason.low2@hp.com>
Cc: "Paul E.McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Alex Shi <alex.shi@linaro.org>
Cc: Michel Lespinasse <walken@google.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1403551009.2970.613.camel@schen9-DESK
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-07-05 11:17:32 +02:00
kernel/printk: use symbolic defines for console loglevels
2014-06-04 16:54:17 -07:00
Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2014-06-12 19:18:49 -07:00
gcov: add support for GCC 4.9
2014-06-10 15:34:46 -07:00
genirq: Improve documentation to match current implementation
2014-05-27 10:16:44 +02:00
Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2014-06-12 18:48:15 -07:00
Merge branch 'pm-sleep'
2014-06-12 13:43:08 +02:00
kernel/printk: use symbolic defines for console loglevels
2014-06-04 16:54:17 -07:00
Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into next
2014-06-03 12:57:53 -07:00
sched/fair: Implement fast idling of CPUs when the system is partially loaded
2014-07-05 11:17:32 +02:00
nohz: Support nohz full remote kick
2014-06-16 16:26:54 +02:00
One bug fix that goes back to 3.10. Accessing a non existent buffer
2014-06-12 21:07:25 -07:00
ipc, kernel: clear whitespace
2014-06-06 16:08:14 -07:00
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
2014-06-12 14:27:40 -07:00
Merge git://git.infradead.org/users/eparis/audit
2014-04-12 12:38:53 -07:00
auditsc: audit_krule mask accesses need bounds checking
2014-06-10 08:44:40 -07:00
kernel/backtracetest.c: replace no level printk by pr_info()
2014-06-04 16:54:14 -07:00
fs,userns: Change inode_capable to capable_wrt_inode_uidgid
2014-06-10 13:57:22 -07:00
Merge branch 'for-3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
2014-06-09 15:03:33 -07:00
cgroup: remove css_parent()
2014-05-16 13:22:48 -04:00
kernel/compat.c: use sizeof() instead of sizeof
2014-06-04 16:54:19 -07:00
asmlinkage: Add explicit __visible to drivers/*, lib/*, kernel/*
2014-05-05 16:07:46 -07:00
More ACPI and power management updates for 3.16-rc1
2014-06-12 13:14:19 -07:00
Merge branch 'for-3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
2014-06-09 15:03:33 -07:00
kernel/exec_domain.c: code clean-up
2014-06-04 16:54:15 -07:00
signals: mv {dis,}allow_signal() from sched.h/exit.c to signal.[ch]
2014-06-06 16:08:11 -07:00
ptrace: fix fork event messages across pid namespaces
2014-06-06 16:08:11 -07:00
Merge branch 'next' (accumulated 3.16 merge window patches) into master
2014-06-08 11:31:16 -07:00
Merge branch 'perf/urgent' into perf/core, to resolve conflict and to prepare for new patches
2014-06-06 07:55:06 +02:00
kernel/hung_task.c: convert simple_strtoul to kstrtouint
2014-06-04 16:54:15 -07:00
irq_work: Remove BUG_ON in irq_work_run()
2014-07-05 11:17:26 +02:00
locking/rwlocks: Introduce 'qrwlocks' - fair, queued rwlocks
2014-06-06 07:58:28 +02:00
kernel/kexec.c: convert printk to pr_foo()
2014-06-06 16:08:12 -07:00
signals: change wait_for_helper() to use kernel_sigaction()
2014-06-06 16:08:12 -07:00
kprobes: Show blacklist entries via debugfs
2014-04-24 10:26:41 +02:00
kobject: Make support for uevent_helper optional.
2014-04-25 12:00:49 -07:00
kthread: fix return value of kthread_create() upon SIGKILL.
2014-06-04 16:53:51 -07:00
kernel/latencytop.c: convert seq_printf to seq_puts
2014-06-04 16:54:15 -07:00
Most of this is cleaning up various driver sysfs permissions so we can
2014-06-11 16:09:14 -07:00
kprobes, notifier: Use NOKPROBE_SYMBOL macro in notifier
2014-04-24 10:26:39 +02:00
kernel/panic.c: add "crash_kexec_post_notifiers" option for kdump after panic_notifers
2014-06-06 16:08:12 -07:00
param: hand arguments after -- straight to init
2014-04-28 11:48:34 +09:30
kernel/profile.c: use static const char instead of static char
2014-06-06 16:08:13 -07:00
kernel/reboot.c: convert simple_strtoul to kstrtoint
2014-06-04 16:54:15 -07:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2014-04-12 14:49:50 -07:00
kernel/res_counter.c: replace simple_strtoull by kstrtoull
2014-06-04 16:54:15 -07:00
resources: Clarify sanity check message
2014-05-23 10:47:21 -06:00
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
2014-06-12 14:27:40 -07:00
signals: introduce kernel_sigaction()
2014-06-06 16:08:12 -07:00
irq_work: Implement remote queueing
2014-06-16 16:26:54 +02:00
Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
2014-05-22 11:36:10 +02:00
kernel/stop_machine.c: kernel-doc warning fix
2014-06-04 16:54:15 -07:00
sched: Consolidate open coded implementations of nice level frobbing into nice_to_rlimit() and rlimit_to_nice()
2014-05-22 11:16:36 +02:00
sys_sgetmask/sys_ssetmask: add CONFIG_SGETMASK_SYSCALL
2014-06-04 16:54:14 -07:00
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
2014-06-12 14:27:40 -07:00
timer: Prevent overflow in apply_slack
2014-04-30 13:46:17 +02:00
torture: Remove __init from torture_init_begin/end
2014-05-14 09:46:30 -07:00
kernel/tracepoint.c: kernel-doc fixes
2014-06-04 16:54:15 -07:00
kernel/user.c: drop unused field 'files' from user_struct
2014-06-04 16:54:16 -07:00
kernel/user_namespace.c: kernel-doc/checkpatch fixes
2014-06-06 16:08:13 -07:00
sysctl: convert use of typedef ctl_table to struct ctl_table
2014-06-06 16:08:16 -07:00
kernel/watchdog.c:touch_softlockup_watchdog(): use raw_cpu_write()
2014-04-18 16:40:08 -07:00
Merge branch 'for-3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
2014-06-09 14:56:49 -07:00
workqueue: rename manager_mutex to attach_mutex
2014-05-20 10:59:32 -04:00
4486edd12b