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())
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This archive was generated by hypermail 2b29 : Thu Jan 31 2002 - 21:01:12 EST