On Fri 2015-07-10 01:22:55, Rafael J. Wysocki wrote:
> On Thursday, July 09, 2015 09:32:51 AM Oliver Neukum wrote:
> > On Thu, 2015-07-09 at 00:03 +0200, Rafael J. Wysocki wrote:
> >
> > > Nothing and I'm not discussing that (I've said that already at least once
> > > in
> > > this thread).
> > >
> > > What I'm questioning is the "why" of calling sys_sync() from the kernel.
> >
> > That's strictly speaking two questions
> >
> > 1. Why do it in the kernel
> >
> > That is easy. It closes the window of a race condition.
> >
> > 2. Why do it at all
> >
> > In essence because the system becomes inactive. For example we say that
> > data hits the disk after 30s maximum. We cannot meet such a limit unless
> > we sync.
>
> Absolute deadlines are not guaranteed to be met at all in general when
> system suspend is used, at least from the user space perspective, so the
> above is quite a bit of an overstretch.
Well, this particular deadline _was_ guaranteed before Len's patch,
and it is useful one, too:
"if notebook is not on, it is ok to pull the USB stick".
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
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http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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