Kernel 3.11-rc1 +Peterz' patch+ Mike's patch, No C-states in BIOS, got the same
result as only Peter's patch.
Of course , No C states to enter, make sense.
[root@localhost ~]# time ./pip1m
real 0m4.381s
user 0m0.099s
sys 0m2.784s
[root@localhost ~]# time ./pip1m
real 0m4.436s
user 0m0.093s
sys 0m2.809s
[root@localhost ~]#
Retest with C-states enabled in BIOS
[root@localhost ~]# time ./pip1m
real 0m8.670s
user 0m0.203s
sys 0m5.459s
[root@localhost ~]# time ./pip1m
real 0m8.489s
user 0m0.184s
sys 0m5.360s
[root@localhost ~]#
So the result is Peter's patch working or Mike's ? Compared with default
3.11-rc3
result of test case 1 as following, looks great.
[root@localhost ~]# time ./pip1m
real 0m10.683s
user 0m0.204s
sys 0m6.597s
[root@localhost ~]# time ./pip1m
real 0m10.629s
user 0m0.185s
sys 0m6.546s
So revert Mike's patch and retest, got
[root@localhost ~]# time ./pip1m
real 0m8.606s
user 0m0.193s
sys 0m5.449s
[root@localhost ~]# time ./pip1m
real 0m8.655s
user 0m0.198s
sys 0m5.519s
[root@localhost ~]#
So, it's Peter's patch working………
The result of kernel 3.11-rc3 + Peter's patch + no rescheduling IPI and no
C-states in BIOS is :
[root@localhost ~]# time ./pip1m
real 0m3.915s
user 0m0.088s
sys 0m2.487s
[root@localhost ~]# time ./pip1m
real 0m3.929s
user 0m0.082s
sys 0m2.560s
[root@localhost ~]# time ./pip1m
Got about 0.5 sec better than only Peter's patch, but it is strange, only no
rescheduling IPI almost got the
same result.
Thanks,
Ethan
在 2013-8-8，下午12:31，ethan.zhao <ethan.ker...@gmail.com> 写道：
>>>
>>> sched: ratelimit nohz
>>>
>>> Entering nohz code on every micro-idle is too expensive to bear.
>>>
>>> Signed-off-by: Mike Galbraith <efa...@gmx.de>
>>>
>>> ---
>>> include/linux/sched.h | 5 +++++
>>> kernel/sched/core.c | 5 +++++
>>> kernel/time/tick-sched.c | 2 +-
>>> 3 files changed, 11 insertions(+), 1 deletion(-)
>>>
>>> --- a/include/linux/sched.h
>>> +++ b/include/linux/sched.h
>>> @@ -235,9 +235,14 @@ extern int runqueue_is_locked(int cpu);
>>> extern void nohz_balance_enter_idle(int cpu);
>>> extern void set_cpu_sd_state_idle(void);
>>> extern int get_nohz_timer_target(void);
>>> +extern int sched_needs_cpu(int cpu);
>>> #else
>>> static inline void nohz_balance_enter_idle(int cpu) { }
>>> static inline void set_cpu_sd_state_idle(void) { }
>>> +static inline int sched_needs_cpu(int cpu)
>>> +{
>>> + return 0;
>>> +}
>>> #endif
>>>
>>> /*
>>> --- a/kernel/sched/core.c
>>> +++ b/kernel/sched/core.c
>>> @@ -650,6 +650,11 @@ static inline bool got_nohz_idle_kick(vo
>>> return false;
>>> }
>>>
>>> +int sched_needs_cpu(int cpu)
>>> +{
>>> + return cpu_rq(cpu)->avg_idle < sysctl_sched_migration_cost;
>>> +}
>>> +
>>> #else /* CONFIG_NO_HZ_COMMON */
>>>
>>> static inline bool got_nohz_idle_kick(void)
>>> --- a/kernel/time/tick-sched.c
>>> +++ b/kernel/time/tick-sched.c
>>> @@ -548,7 +548,7 @@ static ktime_t tick_nohz_stop_sched_tick
>>> time_delta = timekeeping_max_deferment();
>>> } while (read_seqretry(&jiffies_lock, seq));
>>>
>>> - if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) ||
>>> + if (sched_needs_cpu(cpu) || rcu_needs_cpu(cpu, &rcu_delta_jiffies) ||
>>> arch_needs_cpu(cpu) || irq_work_needs_cpu()) {
>>> next_jiffies = last_jiffies + 1;
>>> delta_jiffies = 1;
>>>
>>>
>>
>>
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
