lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Date:	Fri, 26 Sep 2008 10:00:27 +0800
From:	Lin Ming <ming.m.lin@...el.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>,
	mingo <mingo@...e.hu>, Mike Galbraith <efault@....de>
Subject: Re: oltp ~10% regression with 2.6.27-rc5 on stoakley machine

This patch restores ~5% performance.

kernel                  peformance
-----------------------------------
27-rc4                  100%
27-rc5                  89.6%
27-rc5+peter's patch    94.5%

Thanks,
Lin Ming

On Sat, 2008-09-20 at 15:38 -0600, Peter Zijlstra wrote:
> >
> > ------- Comment #4 from ming.m.lin@...el.com  2008-09-17 17:55 -------
> > sched_switch trace of oltp in 2.6.27-rc4
> > http://myfreefilehosting.com/f/fc6c8eaacf_1.31MB
> >
> > sched_switch trace of oltp in 2.6.27-rc5
> > http://myfreefilehosting.com/f/a2f9aea1b0_0.42MB
> >
> > Compared the 2 trace files, you can find that (at most time),
> > with 2.6.27-rc5, mysql switches to sysbench when it's going to sleep
> >           mysqld-3791  [07]   151.421836:   3791:120:R   +  3803:120:S
> >           mysqld-3791  [07]   151.421876:   3791:120:S ==>  3803:120:R
> >         sysbench-3803  [07]   151.421878:   3803:120:R   +  3791:120:S
> >         sysbench-3803  [07]   151.421887:   3803:120:S ==>  3791:120:R
> >
> > with 2.6.27-rc4, mysql switches to sysbench when it's still running
> >           mysqld-3674  [07]    95.960220:   3674:120:R   +  3687:120:S
> >           mysqld-3674  [07]    95.960220:   3674:120:R ==>  3687:120:R
> >         sysbench-3687  [07]    95.960220:   3687:120:S ==>  3674:120:R
> >
> > So with 2.6.27-rc5, sysbench wakes up mysql and then switches to it (mysql is
> > in sleep state)
> >
> > With 2.6.27-rc4, sysbench switches to mysql, no need to wake up it (mysql is
> > still in running state)
> 
> Ming, how does this work for you?
> 
> ---
> Subject: sched: wakeup preempt when small overlap
> 
> Aggresively preempt a task if its avg overlap is very small, this should
> avoid the task going to sleep and find it still running when we schedule
> back to it - saving a wakeup.
> 
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> ---
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 7b4592c..cb44774 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -897,7 +897,7 @@ struct sched_class {
>         void (*yield_task) (struct rq *rq);
>         int  (*select_task_rq)(struct task_struct *p, int sync);
> 
> -       void (*check_preempt_curr) (struct rq *rq, struct task_struct *p);
> +       void (*check_preempt_curr) (struct rq *rq, struct task_struct *p, int sync);
> 
>         struct task_struct * (*pick_next_task) (struct rq *rq);
>         void (*put_prev_task) (struct rq *rq, struct task_struct *p);
> diff --git a/kernel/sched.c b/kernel/sched.c
> index 32d56d6..e17d506 100644
> --- a/kernel/sched.c
> +++ b/kernel/sched.c
> @@ -609,9 +609,9 @@ struct rq {
> 
>  static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
> 
> -static inline void check_preempt_curr(struct rq *rq, struct task_struct *p)
> +static inline void check_preempt_curr(struct rq *rq, struct task_struct *p, int sync)
>  {
> -       rq->curr->sched_class->check_preempt_curr(rq, p);
> +       rq->curr->sched_class->check_preempt_curr(rq, p, sync);
>  }
> 
>  static inline int cpu_of(struct rq *rq)
> @@ -2299,7 +2299,7 @@ out_activate:
> 
>  out_running:
>         trace_sched_wakeup(rq, p);
> -       check_preempt_curr(rq, p);
> +       check_preempt_curr(rq, p, sync);
> 
>         p->state = TASK_RUNNING;
>  #ifdef CONFIG_SMP
> @@ -2432,7 +2432,7 @@ void wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
>                 inc_nr_running(rq);
>         }
>         trace_sched_wakeup_new(rq, p);
> -       check_preempt_curr(rq, p);
> +       check_preempt_curr(rq, p, 0);
>  #ifdef CONFIG_SMP
>         if (p->sched_class->task_wake_up)
>                 p->sched_class->task_wake_up(rq, p);
> @@ -2889,7 +2889,7 @@ static void pull_task(struct rq *src_rq, struct task_struct *p,
>          * Note that idle threads have a prio of MAX_PRIO, for this test
>          * to be always true for them.
>          */
> -       check_preempt_curr(this_rq, p);
> +       check_preempt_curr(this_rq, p, 0);
>  }
> 
>  /*
> @@ -6015,7 +6015,7 @@ static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
>         set_task_cpu(p, dest_cpu);
>         if (on_rq) {
>                 activate_task(rq_dest, p, 0);
> -               check_preempt_curr(rq_dest, p);
> +               check_preempt_curr(rq_dest, p, 0);
>         }
>  done:
>         ret = 1;
> diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
> index a10ac0b..82a907c 100644
> --- a/kernel/sched_fair.c
> +++ b/kernel/sched_fair.c
> @@ -1331,7 +1331,7 @@ static inline int depth_se(struct sched_entity *se)
>  /*
>   * Preempt the current task with a newly woken task if needed:
>   */
> -static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
> +static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int sync)
>  {
>         struct task_struct *curr = rq->curr;
>         struct cfs_rq *cfs_rq = task_cfs_rq(curr);
> @@ -1348,6 +1348,8 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
>         if (unlikely(se == pse))
>                 return;
> 
> +       cfs_rq_of(pse)->next = pse;
> +
>         /*
>          * We can come here with TIF_NEED_RESCHED already set from new task
>          * wake up path.
> @@ -1355,8 +1357,6 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
>         if (test_tsk_need_resched(curr))
>                 return;
> 
> -       cfs_rq_of(pse)->next = pse;
> -
>         /*
>          * Batch tasks do not preempt (their preemption is driven by
>          * the tick):
> @@ -1367,6 +1367,13 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
>         if (!sched_feat(WAKEUP_PREEMPT))
>                 return;
> 
> +       if (sched_feat(WAKEUP_OVERLAP) && sync &&
> +                       se->avg_overlap < sysctl_sched_migration_cost &&
> +                       pse->avg_overlap < sysctl_sched_migration_cost) {
> +               resched_task(curr);
> +               return;
> +       }
> +
>         /*
>          * preemption test can be made between sibling entities who are in the
>          * same cfs_rq i.e who have a common parent. Walk up the hierarchy of
> @@ -1649,7 +1656,7 @@ static void prio_changed_fair(struct rq *rq, struct task_struct *p,
>                 if (p->prio > oldprio)
>                         resched_task(rq->curr);
>         } else
> -               check_preempt_curr(rq, p);
> +               check_preempt_curr(rq, p, 0);
>  }
> 
>  /*
> @@ -1666,7 +1673,7 @@ static void switched_to_fair(struct rq *rq, struct task_struct *p,
>         if (running)
>                 resched_task(rq->curr);
>         else
> -               check_preempt_curr(rq, p);
> +               check_preempt_curr(rq, p, 0);
>  }
> 
>  /* Account for a task changing its policy or group.
> diff --git a/kernel/sched_features.h b/kernel/sched_features.h
> index 9353ca7..bf027a7 100644
> --- a/kernel/sched_features.h
> +++ b/kernel/sched_features.h
> @@ -11,3 +11,4 @@ SCHED_FEAT(ASYM_GRAN, 1)
>  SCHED_FEAT(LB_BIAS, 1)
>  SCHED_FEAT(LB_WAKEUP_UPDATE, 1)
>  SCHED_FEAT(ASYM_EFF_LOAD, 1)
> +SCHED_FEAT(WAKEUP_OVERLAP, 1)
> diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c
> index 3a4f92d..dec4cca 100644
> --- a/kernel/sched_idletask.c
> +++ b/kernel/sched_idletask.c
> @@ -14,7 +14,7 @@ static int select_task_rq_idle(struct task_struct *p, int sync)
>  /*
>   * Idle tasks are unconditionally rescheduled:
>   */
> -static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p)
> +static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int sync)
>  {
>         resched_task(rq->idle);
>  }
> @@ -76,7 +76,7 @@ static void switched_to_idle(struct rq *rq, struct task_struct *p,
>         if (running)
>                 resched_task(rq->curr);
>         else
> -               check_preempt_curr(rq, p);
> +               check_preempt_curr(rq, p, 0);
>  }
> 
>  static void prio_changed_idle(struct rq *rq, struct task_struct *p,
> @@ -93,7 +93,7 @@ static void prio_changed_idle(struct rq *rq, struct task_struct *p,
>                 if (p->prio > oldprio)
>                         resched_task(rq->curr);
>         } else
> -               check_preempt_curr(rq, p);
> +               check_preempt_curr(rq, p, 0);
>  }
> 
>  /*
> diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
> index 04875ef..2e228bd 100644
> --- a/kernel/sched_rt.c
> +++ b/kernel/sched_rt.c
> @@ -787,7 +787,7 @@ static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
>  /*
>   * Preempt the current task with a newly woken task if needed:
>   */
> -static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p)
> +static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int sync)
>  {
>         if (p->prio < rq->curr->prio) {
>                 resched_task(rq->curr);
> 
> 

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ