linux-kernel - Re: [RFC][PATCH] Add prctl to set sibling thread names

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Message-Id: <20091111090141.FD2A.A69D9226@jp.fujitsu.com>
Date:	Wed, 11 Nov 2009 09:04:47 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	john stultz <johnstul@...ibm.com>
Cc:	kosaki.motohiro@...fujitsu.com, Sean Foley <Sean_Foley@...ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>,
	Arjan van de Ven <arjan@...radead.org>,
	Darren Hart <dvhltc@...ibm.com>,
	lkml <linux-kernel@...r.kernel.org>,
	Mike Fulton <fultonm@...ibm.com>
Subject: Re: [RFC][PATCH] Add prctl to set sibling thread names

> On Tue, 2009-11-10 at 14:27 +0900, KOSAKI Motohiro wrote:
> > Hi Sean, John,
> > 
> > > Kosaki,
> > > Here are a couple of use cases previously posted to this thread on the linux kernel mailing list:
> > > 
> > > dispatch thread adds context to thread names:
> > > http://marc.info/?l=linux-kernel&m=125660141231348&w=2
> > > 
> > > java language support:
> > > http://marc.info/?l=linux-kernel&m=125666430720863&w=2
> > > 
> > > 
> > > 
> > > Here are some various specific use cases from the web:
> > > 
> > > Attaching additional info to thread names when used for different purposes:
> > > http://osdir.com/ml/java.jsr.166-concurrency/2006-12/msg00105.html
> > > 
> > > Threads obtained from thread pools being reassigned new names:
> > > http://haacked.com/archive/2004/06/07/546.aspx
> > > http://bytes.com/topic/c-sharp/answers/637152-naming-backgroundworker-thread
> > > 
> > > Renaming threads scattered across third-party libraries by enumerating them and renaming them dynamically:
> > > http://stackoverflow.com/questions/467224/renaming-threads-in-java
> > 
> > Okey, good explanation. thanks!
> > 
> > So, I would suggested to extend /proc/{pid}/cmdline instead using task->comm.
> > because 
> >   - task->comm has nasty locking rule. It is harder to change SMP safe.
> 
> I cc'ed you on the updated patch which addresses this. Please let me
> know if you have specific concerns there.
> 
> >   - ps (and other procps tools) already support /proc/{pid}/cmdline.
> >   - task->comm is restrected 16 character length, /proc/cmdline isn't.
> 
> Part of the reason to use comm is that most tools like perf or oprofile,
> use comm, instead of cmd. 

Ah, good reason. Okey, I will revew your new patch.

thanks.


> Additionally, looking at cmdline, that's per
> mm not per task, right? So it wouldn't really work for thread names. 

Currently, yes. I meaned I think you can enhance it ;)

> Please correct me if I'm not seeing what you're really suggesting.



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