From: Andrew Morton <akpm@zip.com.au>
To: Robert Love <rml@tech9.net>
Cc: Linus Torvalds <torvalds@transmeta.com>,
viro@math.psu.edu, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] 2.5: push BKL out of llseek
Date: Tue, 29 Jan 2002 18:20:27 -0800 [thread overview]
Message-ID: <3C57586B.7B145D16@zip.com.au> (raw)
In-Reply-To: <3C574BD1.E5343312@zip.com.au>, <Pine.LNX.4.33.0201291602510.1747-100000@penguin.transmeta.com>, <Pine.LNX.4.33.0201291602510.1747-100000@penguin.transmeta.com> <1012351309.813.56.camel@phantasy> <3C574BD1.E5343312@zip.com.au> <1012357211.817.67.camel@phantasy>
Robert Love wrote:
>
> On Tue, 2002-01-29 at 20:26, Andrew Morton wrote:
>
> > Just a little word of caution here. Remember the
> > apache-flock-synchronisation fiasco, where removal
> > of the BKL halved Apache throughput on 8-way x86.
> >
> > This was because the BKL removal turned serialisation
> > on a quick codepath from a spinlock into a schedule().
>
> I feared this too, but eventually I decided it was worth it and
> benchmarks backed that up. If nothing else this is yet-another-excuse
> for locks that can spin-then-sleep.
>
> I posted dbench results, which show a positive gain even on 2-way for
> multiple client loads.
>
But dbench does lots of seeking against *different* files,
so removal of a shared lock will help there.
But an application where multiple CPUs lseek and write
the *same* file could take a hit....
(And where's the locking for (non-atomic) i_size in sys_stat())
-
next prev parent reply other threads:[~2002-01-30 2:27 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-01-30 0:00 [PATCH] 2.5: push BKL out of llseek Robert Love
2002-01-30 0:09 ` Linus Torvalds
2002-01-30 0:41 ` Robert Love
2002-01-30 0:52 ` Linus Torvalds
2002-01-30 2:24 ` Robert Love
2002-01-30 1:26 ` Andrew Morton
2002-01-30 2:16 ` Linus Torvalds
2002-01-30 2:20 ` Robert Love
2002-01-30 2:20 ` Andrew Morton [this message]
2002-01-30 2:21 ` Dave Jones
2002-01-30 2:37 ` Robert Love
2002-01-30 2:50 ` Nigel Gamble
2002-01-30 3:19 ` Andrew Morton
2002-01-30 9:34 ` Nigel Gamble
2002-01-30 10:36 ` Russell King
2002-01-30 4:54 ` Alexander Viro
2002-01-30 8:00 ` Trond Myklebust
2002-01-30 13:39 ` Robert Love
2002-01-30 4:50 ` Anton Blanchard
2002-01-30 5:03 ` Robert Love
-- strict thread matches above, loose matches on Subject: below --
2002-01-30 21:14 Martin Wirth
2002-01-31 15:39 Martin Wirth
2002-01-31 21:06 ` Nigel Gamble
2002-02-01 19:29 John Hawkes
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