Messages in this thread | | | Date | Wed, 30 Jan 2002 10:36:40 +0000 | From | Russell King <> | Subject | Re: [PATCH] 2.5: push BKL out of llseek |
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On Tue, Jan 29, 2002 at 09:20:10PM -0500, 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.
Luckily, apache on its own doesn't seem to use lseek() when sending the file - it seems to be an open, mmap, write. (apache 1.3.22)
However, php with apache does do an lseek on the target script. Now remember the /. effect... You'll be accessing the same file from several apache or php processes.
-- Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux http://www.arm.linux.org.uk/personal/aboutme.html - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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