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Date: Thu, 26 Mar 2009 20:55:34 +0000
From: Matthew Garrett <mjg@redhat.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
       Theodore Tso <tytso@mit.edu>, Ingo Molnar <mingo@elte.hu>,
       Jan Kara <jack@suse.cz>, Andrew Morton <akpm@linux-foundation.org>,
       Arjan van de Ven <arjan@infradead.org>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>, Nick Piggin <npiggin@suse.de>,
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       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Oleg Nesterov <oleg@redhat.com>, Roland McGrath <roland@redhat.com>
Subject: Re: ext3 IO latency measurements (was: Linux 2.6.29)
Message-ID: <20090326205534.GA11217@srcf.ucam.org>
References: <20090326090630.GA9369@elte.hu> <20090326113705.GV32307@mit.edu> <20090326140312.GB14822@elte.hu> <20090326144707.GA6239@mit.edu> <alpine.LFD.2.00.0903260914440.3032@localhost.localdomain> <20090326170714.GF6239@mit.edu> <alpine.LFD.2.00.0903261015050.3032@localhost.localdomain> <20090326185900.166a1097@lxorguk.ukuu.org.uk> <20090326200258.GA10313@srcf.ucam.org> <20090326204209.1da6e791@lxorguk.ukuu.org.uk>
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On Thu, Mar 26, 2009 at 08:42:09PM +0000, Alan Cox wrote:
> > before performing the update. So while relatime doesn't conform, the 
> > practical difference is meaningless. You can't depend on atime being 
> > updated in a timely manner.
> 
> POSIX says a disk write interrupted by a signal can be a short write. If
> you do this in practice all hell breaks loose.
> 
> A conforming implementation needs to conform with expectations not just
> play lawyer games with users systems.

I agree, but arguing for something on the basis of a spec isn't terribly 
convincing if the spec allows effectively identical behaviour. SuS isn't 
a relevant consideration when it comes to deciding default atime policy.

-- 
Matthew Garrett | mjg59@srcf.ucam.org
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