linux-kernel - Re: [rfc] Ignore Fsync Calls in Laptop

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Message-Id: <201105300913.27971.oneukum@suse.de>
Date:	Mon, 30 May 2011 09:13:27 +0200
From:	Oliver Neukum <oneukum@...e.de>
To:	david@...g.hm
Cc:	"D. Jansen" <d.g.jansen@...glemail.com>,
	Theodore Tso <tytso@....edu>, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, Dave Chinner <david@...morbit.com>,
	njs@...ox.com, bart@...wel.tk
Subject: Re: [rfc] Ignore Fsync Calls in Laptop_Mode

Am Montag, 30. Mai 2011, 03:53:18 schrieb david@...g.hm:
> > So what if we would queue the fsyncs along with the writes - we would
> > just fsync later instead of immediately, in between the writes as they
> > came in. Then by design previous data could not be corrupted, right?
> > We would do exactly the same thing, just later.
> > It'd be kind of a disk write time distortion field.
> 
> the problem is that the spec for fsync says that your program stops until 
> fsync finishes. If you don't do that then you will corrupt and loose data.

It is important to be precise.
You will loose data, but you will not get corruption.

> so if you delay fsync you will have your application (or desktop manager) 
> freeze until the fsync completes.
> 
> if what you are wanting is the ability to say 'these things must be 
> written before these other things to keep them from being corrupted, but I 
> don't care when they get written (or if they get lost in a crash)' then 
> what you want isn't fsync, it's a barrier.

Yes, but where is the problem?

	Regards
		Oliver
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