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 1/7] timers: Sanitize catchup_timer_jiffies() usage
Date: Wed, 27 May 2015 11:09:19 +0530 [thread overview]
Message-ID: <20150527053919.GD31085@linux> (raw)
In-Reply-To: <20150526224511.662994644@linutronix.de>
On 26-05-15, 22:50, Thomas Gleixner wrote:
> 3) __run_timers()
>
> We only check on entry, which is silly, because base->timer_jiffies
> can be behind - especially on NOHZ kernels - and if there is a
> single deferrable timer somewhere between base->timer_jiffies and
> jiffies we expire it and then loop until base->timer_jiffies ==
> jiffies.
This may be incorrect. Once we expire that single deferrable timer, we
call detach_expired_timer(), which calls catchup_timer_jiffies() at
its end. And so the following loop should end right away, isn't it ?
while (time_after_eq(jiffies, base->timer_jiffies))
> +++ tip/kernel/time/timer.c
> -static bool catchup_timer_jiffies(struct tvec_base *base)
> +static inline bool catchup_timer_jiffies(struct tvec_base *base)
There is only one user left for this routine now, i.e. __run_timers().
Should we drop this routine ?
--
viresh
next prev parent reply other threads:[~2015-05-27 5:39 UTC|newest]
Thread overview: 27+ 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 [this message]
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
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
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