linux-kernel - Re: Re: [PATCH 4/4] trace_workqueue: Add worklet information

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Message-ID: <20090421233935.GC6744@nowhere>
Date:	Wed, 22 Apr 2009 01:39:36 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Zhaolei <zhaolei@...fujitsu.com>
Cc:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Tom Zanussi <tzanussi@...il.com>, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org, Oleg Nesterov <oleg@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: Re: [PATCH 4/4] trace_workqueue: Add worklet information

On Tue, Apr 21, 2009 at 09:57:02AM +0800, Zhaolei wrote:
> Hello, Frederic
> 
> Thanks for your review and advice.
> 
> > 
> > The above test will take the total number of cpus as
> > the last cpu number. This assumption may be false
> > if the possible cpus are not contiguous.
> > 
> > Perhaps you'd better use:
> > 
> > 
> > for_each_possible_cpu(cpu) {
> > 	ret = workqueue_stat_start_cpu(cpu);
> > 	if (ret)
> > 		break;
> > }
> IMHO, this code is to choose first cpu who have workqueue.
> But we need to choose next cpu, may be we need to:
> 
> int nextcpu;
> for_each_possible_cpu(nextcpu) {
> 	/* bypass prev cpus */
> 	if (nextcpu <= cpu)
> 		continue;
> 
> 	ret = workqueue_stat_start_cpu(cpu);
> 	if (ret) {
> 		break;
> 	}
> }
> 
> By looking cpumask.h, for_each_possible_cpu(nextcpu) always make nextcpu
> increase, but if not(in future?), above code is wrong.
> 
> Thanks
> Zhaolei
> 


Ok.

BTW, I've applied your patches in
git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git tracing/workqueue

Once I have some time, I will also address Oleg's comments.

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