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From: Viresh Kumar <viresh.kumar@linaro.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Paul McKenney <paulmck@linux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Eric Dumazet <edumazet@google.com>,
	John Stultz <john.stultz@linaro.org>,
	Joonwoo Park <joonwoop@codeaurora.org>,
	Wenbo Wang <wenbo.wang@memblaze.com>
Subject: Re: [patch 2/7] timer: Remove FIFO guarantee
Date: Wed, 27 May 2015 14:41:59 +0530	[thread overview]
Message-ID: <20150527091159.GA2256@linux> (raw)
In-Reply-To: <20150526224511.757520403@linutronix.de>

On 26-05-15, 22:50, Thomas Gleixner wrote:
> The FIFO guarantee has been violated by the introduction of timer
> slack already. Remove it.
> 
> This is a preparatory patch for converting the timer wheel to hlist
> which reduces the memory foot print of the wheel by 50%. It's a
> seperate patch so any (unlikely to happen) regression caused by this
> can be identified clearly.
> 
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
>  kernel/time/timer.c |    6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> Index: tip/kernel/time/timer.c
> ===================================================================
> --- tip.orig/kernel/time/timer.c
> +++ tip/kernel/time/timer.c
> @@ -403,10 +403,8 @@ __internal_add_timer(struct tvec_base *b
>  		i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
>  		vec = base->tv5.vec + i;
>  	}
> -	/*
> -	 * Timers are FIFO:
> -	 */
> -	list_add_tail(&timer->entry, vec);
> +
> +	list_add(&timer->entry, vec);
>  }

Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>

-- 
viresh

  reply	other threads:[~2015-05-27  9:12 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-26 22:50 [patch 0/7] timers: Footprint diet and NOHZ overhead mitigation Thomas Gleixner
2015-05-26 22:50 ` [patch 1/7] timers: Sanitize catchup_timer_jiffies() usage Thomas Gleixner
2015-05-27  5:39   ` Viresh Kumar
2015-06-19 13:22   ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-05-26 22:50 ` [patch 2/7] timer: Remove FIFO guarantee Thomas Gleixner
2015-05-27  9:11   ` Viresh Kumar [this message]
2015-06-19 13:22   ` [tip:timers/core] timer: Remove FIFO "guarantee" tip-bot for Thomas Gleixner
2015-05-26 22:50 ` [patch 3/7] timer: Use hlist for the timer wheel hash buckets Thomas Gleixner
2015-05-27  9:13   ` Viresh Kumar
2015-06-19 13:23   ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-05-26 22:50 ` [patch 4/7] timer: Replace timer base by a cpu index Thomas Gleixner
2015-05-27  9:22   ` Viresh Kumar
2015-05-27 12:09     ` Peter Zijlstra
2015-06-02 13:58       ` Thomas Gleixner
2015-06-19 13:23   ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-06-27  9:55   ` [PATCH] timer: Fix unsafe cpu variable access in migrate_timers Jan Kiszka
2015-06-27 11:00     ` Borislav Petkov
2015-06-27 11:19       ` Jan Kiszka
2015-06-27 11:25         ` Borislav Petkov
2015-05-26 22:50 ` [patch 5/7] timer: stats: Simplify the flags handling Thomas Gleixner
2015-06-19 13:23   ` [tip:timers/core] timer: Stats: " tip-bot for Thomas Gleixner
2015-05-26 22:50 ` [patch 6/7] timer: Reduce timer migration overhead if disabled Thomas Gleixner
2015-06-19 13:23   ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-05-26 22:50 ` [patch 7/7] timer: Minimize nohz off overhead Thomas Gleixner
2015-06-19 13:24   ` [tip:timers/core] " tip-bot for Thomas Gleixner
2015-05-27 14:53 ` [patch 0/7] timers: Footprint diet and NOHZ overhead mitigation Eric Dumazet
2015-06-02 13:58   ` Thomas Gleixner
  -- strict thread matches above, loose matches on Subject: below --
2015-06-05 22:27 [patch 2/7] timer: Remove FIFO guarantee George Spelvin
2015-06-08 17:48 ` Thomas Gleixner
2015-06-09  5:39   ` George Spelvin
2015-06-09  8:05     ` Thomas Gleixner
2015-06-09  9:43       ` George Spelvin
2015-06-09 10:24         ` Peter Zijlstra
2015-06-09 11:15           ` George Spelvin

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