[patch] Re: stalled 'sync' on ext3+quota over drbd
Stephen C. Tweedie
sct at redhat.com
Tue Apr 20 10:06:28 UTC 2004
On Mon, 2004-04-19 at 19:27, Eugene Crosser wrote:
> > From the first impression, it did not help.
> Luckily, I was wrong. At least on the test environment I get the
> results below. This is 2.6.5 kernel with euivalent of Stephen's patch.
> 'setquota' sets user and group quota for 40,000 userids and 40,000
> groupids. 'mktree' writes one byte into 40,000 files and sets their
> owner and group to 40,000 unique values.
> unpatched patched
> sync 7m50 0m0.8
OK, that's a win. :-)
> On my 'big' system sync still runs unexpectedly long (40sec - 4min) but
> it is by far better than it was before the patch...
That's quote possibly just the raw cost of writing out a million
dquots. The overhead of the list traversal should be under control now,
though. A profile would help determine what the remaining cost is: is
that time spent in the CPU, or in IO wait?
Jan, mind if I push the patch to 2.4? Your locking concern seems to be
2.6-only; on 2.4, BKL should be sufficient protection even on SMP.
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