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From: Miklos Szeredi <miklos@szeredi.hu>
To: torvalds@linux-foundation.org
Cc: miklos@szeredi.hu, peterz@infradead.org, salikhmetov@gmail.com,
	linux-mm@kvack.org, jakob@unthought.net,
	linux-kernel@vger.kernel.org, valdis.kletnieks@vt.edu,
	riel@redhat.com, ksm@42.dk, staubach@redhat.com,
	jesper.juhl@gmail.com, akpm@linux-foundation.org,
	protasnb@gmail.com, r.e.wolff@bitwizard.nl,
	hidave.darkstar@gmail.com, hch@infradead.org
Subject: Re: [PATCH -v6 2/2] Updating ctime and mtime for memory-mapped files
Date: Fri, 18 Jan 2008 20:22:32 +0100	[thread overview]
Message-ID: <E1JFwnQ-0001FB-2c@pomaz-ex.szeredi.hu> (raw)
In-Reply-To: <alpine.LFD.1.00.0801181106340.2957@woody.linux-foundation.org> (message from Linus Torvalds on Fri, 18 Jan 2008 11:08:57 -0800 (PST))

> > 
> > But then background writeout, sync(2), etc, wouldn't update the times.
> 
> Sure it would, but only when doing the final unmap.
> 
> Did you miss the "on unmap and msync" part?

No :)

What I'm saying is that the times could be left un-updated for a long
time if program doesn't do munmap() or msync(MS_SYNC) for a long time.

If program has this pattern:

mmap()
write to map
msync(MS_ASYNC)
sleep(long)
write to map
msync(MS_ASYNC)
sleep(long)
...

Then we'd never see time updates (until the program exits, but that
could be years).

Maybe this doesn't matter, I'm just saying this is a disadvantage
compared to the "update on first dirtying" approach, which would
ensure, that times are updated at least once per 30s.

Miklos

  reply	other threads:[~2008-01-18 19:22 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-17 22:31 [PATCH -v6 0/2] Fixing the issue with memory-mapped file times Anton Salikhmetov
2008-01-17 22:31 ` [PATCH -v6 1/2] Massive code cleanup of sys_msync() Anton Salikhmetov
2008-01-18  9:33   ` Miklos Szeredi
2008-01-18 10:30     ` Anton Salikhmetov
2008-01-17 22:31 ` [PATCH -v6 2/2] Updating ctime and mtime for memory-mapped files Anton Salikhmetov
2008-01-18  9:51   ` Miklos Szeredi
2008-01-18 10:15     ` Peter Zijlstra
2008-01-18 10:25       ` Peter Zijlstra
2008-01-18 10:39         ` Anton Salikhmetov
2008-01-18 17:58         ` Linus Torvalds
2008-01-18 18:11           ` Miklos Szeredi
2008-01-18 18:28             ` Rik van Riel
2008-01-18 18:51               ` Miklos Szeredi
2008-01-18 18:43             ` Linus Torvalds
2008-01-18 18:57               ` Miklos Szeredi
2008-01-18 19:08                 ` Linus Torvalds
2008-01-18 19:22                   ` Miklos Szeredi [this message]
2008-01-18 19:35                     ` Linus Torvalds
2008-01-18 19:58                       ` Anton Salikhmetov
2008-01-18 20:22                         ` Linus Torvalds
2008-01-18 21:03                           ` Anton Salikhmetov
2008-01-18 21:27                             ` Linus Torvalds
2008-01-18 22:04                               ` Anton Salikhmetov
2008-01-18 22:21                                 ` Linus Torvalds
2008-01-18 22:35                                   ` Anton Salikhmetov
2008-01-18 22:32                       ` Ingo Oeser
2008-01-18 22:47                         ` Linus Torvalds
2008-01-18 22:54                           ` Rik van Riel
2008-01-19  0:50                             ` Matt Mackall
2008-01-19  4:25                               ` Rik van Riel
2008-01-19 10:22                               ` Miklos Szeredi
2008-01-19 15:49                                 ` Matt Mackall
2008-01-21 14:25                           ` Peter Staubach
2008-01-21 14:36                             ` Anton Salikhmetov
2008-01-18 10:38       ` Miklos Szeredi
2008-01-18 11:00         ` Peter Zijlstra
2008-01-18 11:17           ` Miklos Szeredi
2008-01-18 11:23             ` Peter Zijlstra
2008-01-18 11:36               ` Miklos Szeredi
2008-01-18  9:40 ` [PATCH -v6 0/2] Fixing the issue with memory-mapped file times Miklos Szeredi
2008-01-18 10:31   ` Anton Salikhmetov
2008-01-18 19:48   ` Anton Salikhmetov
2008-01-19 10:45     ` Miklos Szeredi

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