Re: [PATCH -v6 2/2] Updating ctime and mtime for memory-mapped files

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To: Peter Zijlstra <peterz@...>
Cc: Miklos Szeredi <miklos@...>, <salikhmetov@...>, <linux-mm@...>, <jakob@...>, <linux-kernel@...>, <valdis.kletnieks@...>, <riel@...>, <ksm@...>, <staubach@...>, <jesper.juhl@...>, <akpm@...>, <protasnb@...>, <r.e.wolff@...>, <hidave.darkstar@...>, <hch@...>
Date: Friday, January 18, 2008 - 1:58 pm

On Fri, 18 Jan 2008, Peter Zijlstra wrote:

No, we simply want to not play all these very expensive games with dirty 
in the first place.

Guys, mmap access times aren't important enough for this. It's not 
specified closely enough, and people don't care enough.

Of the patches around so far, the best one by far seems to be the simple 
four-liner from Miklos.

And even in that four-liner, I suspect that the *last* two lines are 
actually incorrect: there's no point in updating the file time when the 
page *becomes* dirty, we should update the file time when it is marked 
clean, and "msync(MS_SYNC)" should update it as part of *that*.

So I think the file time update should be part of just the page writeout 
logic, not by msync() or page faulting itself or anything like that.

		Linus
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Messages in current thread:
[PATCH -v6 0/2] Fixing the issue with memory-mapped file times, Anton Salikhmetov, (Thu Jan 17, 6:31 pm)
Re: [PATCH -v6 0/2] Fixing the issue with memory-mapped file..., Anton Salikhmetov, (Fri Jan 18, 3:48 pm)
Re: [PATCH -v6 0/2] Fixing the issue with memory-mapped file..., Anton Salikhmetov, (Fri Jan 18, 6:31 am)
[PATCH -v6 2/2] Updating ctime and mtime for memory-mapped f..., Anton Salikhmetov, (Thu Jan 17, 6:31 pm)
Re: [PATCH -v6 2/2] Updating ctime and mtime for memory-mapp..., Linus Torvalds, (Fri Jan 18, 1:58 pm)
Re: [PATCH -v6 2/2] Updating ctime and mtime for memory-mapp..., Anton Salikhmetov, (Mon Jan 21, 10:36 am)
Re: [PATCH -v6 2/2] Updating ctime and mtime for memory-mapp..., Anton Salikhmetov, (Fri Jan 18, 3:58 pm)
Re: [PATCH -v6 2/2] Updating ctime and mtime for memory-mapp..., Anton Salikhmetov, (Fri Jan 18, 5:03 pm)
Re: [PATCH -v6 2/2] Updating ctime and mtime for memory-mapp..., Anton Salikhmetov, (Fri Jan 18, 6:04 pm)
Re: [PATCH -v6 2/2] Updating ctime and mtime for memory-mapp..., Anton Salikhmetov, (Fri Jan 18, 6:35 pm)
Re: [PATCH -v6 2/2] Updating ctime and mtime for memory-mapp..., Anton Salikhmetov, (Fri Jan 18, 6:39 am)
[PATCH -v6 1/2] Massive code cleanup of sys_msync(), Anton Salikhmetov, (Thu Jan 17, 6:31 pm)
Re: [PATCH -v6 1/2] Massive code cleanup of sys_msync(), Miklos Szeredi, (Fri Jan 18, 5:33 am)
Re: [PATCH -v6 1/2] Massive code cleanup of sys_msync(), Anton Salikhmetov, (Fri Jan 18, 6:30 am)