linux-kernel - Re: [PATCH] relay: fix timer madness

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Date:	Wed, 31 Jul 2013 18:38:26 +0800
From:	"zhangwei(Jovi)" <jovi.zhangwei@...wei.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...hat.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Dan Carpenter <dan.carpenter@...cle.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Jens Axboe <axboe@...nel.dk>,
	Al Viro <viro@...iv.linux.org.uk>,
	Eric Dumazet <edumazet@...gle.com>
Subject: Re: [PATCH] relay: fix timer madness

On 2013/7/31 18:01, zhangwei(Jovi) wrote:
> From: Ingo Molnar <mingo@...e.hu>
> 
> When I'm using ktap script to tracing all event tracepoints by relay
> transport, without this patch, the system will hang in few seconds.
> 
> I found the original patch discussion in 2007.
> http://marc.info/?l=linux-kernel&m=118544794717162&w=2
> (In that mail thread, the patch didn't fix that problem, but it fix
> the problem I encountered now)
> 
> Changed from origina patch:
>  - mod timer interval changed from jiffies+1 to HZ/10, as Ingo suggested.
>  - mod timer interval changed from HZ/10 to jiffies + HZ/10, suggested
>    by Dan Carpenter, since mod_timer() takes an offset for interval.
> 
> Original patch changelog from Ingo in 2007:
> 
>   Remove timer calls (!!!) from deep within the tracing infrastructure.
>   This was totally bogus code that can cause lockups and worse.
>   Poll the buffer every 2 jiffies for now.
> 
> Signed-off-by: Ingo Molnar <mingo@...e.hu>
> Signed-off-by: "zhangwei(Jovi)" <jovi.zhangwei@...wei.com>
> Cc: Dan Carpenter <dan.carpenter@...cle.com>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Jens Axboe <axboe@...nel.dk>
> Cc: Al Viro <viro@...iv.linux.org.uk>
> Cc: Eric Dumazet <edumazet@...gle.com>
> ---
Hi Andrew,

How about this patch? this version folded the suggestion from Ingo and Dan.

jovi

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