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Date: Fri, 18 Nov 2011 16:22:06 +0100
From: Mike Galbraith <efault@....de>
To: Suresh Siddha <suresh.b.siddha@...el.com>
Cc: Peter Zijlstra <peterz@...radead.org>,
linux-kernel <linux-kernel@...r.kernel.org>,
Ingo Molnar <mingo@...e.hu>, Paul Turner <pjt@...gle.com>
Subject: [patch 5/6] sched: save some hrtick_start_fair cycles
hrtick_start_fair() shows up in profiles even when disabled.
v3.0.6
taskset -c 3 pipe-test
PerfTop: 997 irqs/sec kernel:89.5% exact: 0.0% [1000Hz cycles], (all, CPU: 3)
------------------------------------------------------------------------------------------------
Virgin Patched
samples pcnt function samples pcnt function
_______ _____ ___________________________ _______ _____ ___________________________
2880.00 10.2% __schedule 3136.00 11.3% __schedule
1634.00 5.8% pipe_read 1615.00 5.8% pipe_read
1458.00 5.2% system_call 1534.00 5.5% system_call
1382.00 4.9% _raw_spin_lock_irqsave 1412.00 5.1% _raw_spin_lock_irqsave
1202.00 4.3% pipe_write 1255.00 4.5% copy_user_generic_string
1164.00 4.1% copy_user_generic_string 1241.00 4.5% __switch_to
1097.00 3.9% __switch_to 929.00 3.3% mutex_lock
872.00 3.1% mutex_lock 846.00 3.0% mutex_unlock
687.00 2.4% mutex_unlock 804.00 2.9% pipe_write
682.00 2.4% native_sched_clock 713.00 2.6% native_sched_clock
643.00 2.3% system_call_after_swapgs 653.00 2.3% _raw_spin_unlock_irqrestore
617.00 2.2% sched_clock_local 633.00 2.3% fsnotify
612.00 2.2% fsnotify 605.00 2.2% sched_clock_local
596.00 2.1% _raw_spin_unlock_irqrestore 593.00 2.1% system_call_after_swapgs
542.00 1.9% sysret_check 559.00 2.0% sysret_check
467.00 1.7% fget_light 472.00 1.7% fget_light
462.00 1.6% finish_task_switch 461.00 1.7% finish_task_switch
437.00 1.5% vfs_write 442.00 1.6% vfs_write
431.00 1.5% do_sync_write 428.00 1.5% do_sync_write
413.00 1.5% select_task_rq_fair 404.00 1.5% _raw_spin_lock_irq
386.00 1.4% update_curr 402.00 1.4% update_curr
385.00 1.4% rw_verify_area 389.00 1.4% do_sync_read
377.00 1.3% _raw_spin_lock_irq 378.00 1.4% vfs_read
369.00 1.3% do_sync_read 340.00 1.2% pipe_iov_copy_from_user
360.00 1.3% vfs_read 316.00 1.1% __wake_up_sync_key
* 342.00 1.2% hrtick_start_fair 313.00 1.1% __wake_up_common
Signed-off-by: Mike Galbraith <efault@....de>
---
kernel/sched_fair.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
Index: linux-3.2.git/kernel/sched_fair.c
===================================================================
--- linux-3.2.git.orig/kernel/sched_fair.c
+++ linux-3.2.git/kernel/sched_fair.c
@@ -1853,7 +1853,7 @@ static void hrtick_start_fair(struct rq
WARN_ON(task_rq(p) != rq);
- if (hrtick_enabled(rq) && cfs_rq->nr_running > 1) {
+ if (cfs_rq->nr_running > 1) {
u64 slice = sched_slice(cfs_rq, se);
u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
s64 delta = slice - ran;
@@ -1884,7 +1884,7 @@ static void hrtick_update(struct rq *rq)
{
struct task_struct *curr = rq->curr;
- if (curr->sched_class != &fair_sched_class)
+ if (!hrtick_enabled(rq) || curr->sched_class != &fair_sched_class)
return;
if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency)
@@ -2643,7 +2643,8 @@ static struct task_struct *pick_next_tas
} while (cfs_rq);
p = task_of(se);
- hrtick_start_fair(rq, p);
+ if (hrtick_enabled(rq))
+ hrtick_start_fair(rq, p);
return p;
}
--
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