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Date: Wed, 22 Apr 2009 01:39:36 +0200
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Zhaolei <zhaolei@cn.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
       Steven Rostedt <rostedt@goodmis.org>, Tom Zanussi <tzanussi@gmail.com>,
       Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org,
       Oleg Nesterov <oleg@redhat.com>,
       Andrew Morton <akpm@linux-foundation.org>
Subject: Re: Re: [PATCH 4/4] trace_workqueue: Add worklet information
Message-ID: <20090421233935.GC6744@nowhere>
References: <20090415085310.AC0D.A69D9226@jp.fujitsu.com> <20090415011533.GI5968@nowhere> <20090415141250.AC46.A69D9226@jp.fujitsu.com> <49EC1943.8080606@cn.fujitsu.com> <49EC1F99.9030208@cn.fujitsu.com> <20090420113601.GC6081@nowhere> <49ED27EE.8080600@cn.fujitsu.com>
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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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