linux-kernel - Re: [Question]: try to fix contention between expire_timers and try_to_del_timer

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Message-ID: <bf81be7b-4d6c-acd4-4f80-b8cfbbee625f@asrmicro.com>
Date:   Wed, 11 Oct 2017 16:33:03 +0800
From:   qiaozhou <qiaozhou@...micro.com>
To:     Will Deacon <will.deacon@....com>
CC:     Vikram Mulukutla <markivx@...eaurora.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        John Stultz <john.stultz@...aro.org>, <sboyd@...eaurora.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Wang Wilbur <wilburwang@...micro.com>,
        Marc Zyngier <marc.zyngier@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        <linux-kernel-owner@...r.kernel.org>, <sudeep.holla@....com>
Subject: Re: [Question]: try to fix contention between expire_timers and
 try_to_del_timer_sync

Hi Will,

On 2017年10月02日 22:14, Will Deacon wrote:
> Hi Qiao,
> 
> On Mon, Sep 25, 2017 at 07:02:03PM +0800, qiaozhou wrote:
>> Will this bodging patch be merged? It can solve the livelock issue on arm64
>> platforms(at least improve a lot).
> 
> Whilst it seemed to help in some cases, I'm not keen to merge it until
> we've identified a sensible way to parameterise the threshold and also
> explain why it doens't appear to help at all on some platforms. I guess
> I could respin a version that takes the threshold on the cmdline and
> also checks to see that the event stream is enabled, since that might
> help with further benchmarking.
> 
> Would that be useful?

Got it. Please let me know if you want to verify it on my platform. Many 
thanks.

Best Regards
Qiao