Re: Pre-approval request for dpkg sync() changes for squeeze
On Wed, 10 Nov 2010, Philipp Kern wrote:
> On Tue, Nov 09, 2010 at 07:50:23PM +0100, Philipp Kern wrote:
> > On Fri, Oct 22, 2010 at 11:35:54AM +0200, Guillem Jover wrote:
> > > 1) Switch back from sync() to fsync() before rename() (while keeping
> > > the sync() code around for the benefit of other distributions
> > > that might not want to switch just yet). So to avoid unrelated
> > > I/O when there's background work being done for example. This
> > > hack also only works on Linux where sync() is synchronous, so
> > > it would unify that code path for all dpkg supported platforms.
> > >
> > > Bug: #588339
> > >
> > > <http://git.hadrons.org/?p=debian/dpkg/dpkg.git;a=commitdiff;h=87740373>
> > I'm still not sure we have all needed information. Would you mind doing
> > a matrix what this change would cause? I.e. if we get performance
> > regressions on ext4, btrfs or even ext3 with the squeeze kernel (we're
> > really only interested in that one, not some random other revision)
> > or if we even get data safety regressions.
> I also forgot to throw nfs into the picture.
I'm sorry, I won't have the time to do new benchmarks on this.
The only benchmarks we have have been made by Sven Joachim:
(asyncsync is the switch to sync() instead of fsync() so the opposite of
the above patch)
He mentionned that without the sync() trick it takes 3 to 5 times longer
to unpack a package.
Sven, would you have time to provide some of the stats asked by the
We really need to upload dpkg this week so we must take a decision what
Raphaël Hertzog ◈ Debian Developer ◈ [Flattr=20693]
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