Re: [Ext2-devel] Re: fsync 50 times slower after 2.5.27

From: Stephen C. Tweedie (
Date: Thu Sep 19 2002 - 16:44:36 EST


On Thu, Sep 19, 2002 at 02:22:30PM -0700, Andrew Morton wrote:

> Thanks for testing. The semantics of sched_yield() have changed
> significantly in 2.5. Probably correctly, but it is breaking a
> few things which were tuned for the old semantics. Amongst those
> things are OpenOffice and, it seems, ext3 transaction batching.
> The transaction batching does good things under some situations,
> and we want it to keep working. I'll sit tight for the while, see
> where shed_yield() behaviour ends up. If we still have a problem
> then probably a schedule_timeout(1) in there would suffice.

Actually, with a proper yield() implementation, we can achieve the
same effect by making the commit thread do the yield itself before
locking down the transaction. Having _every_ sync thread do a yield
itself before calling for a commit is probably overkill.

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