Date: Wed, 20 Sep 2006 12:45:37 +0400 (MSD) From: Dmitry Morozovsky <marck@rinet.ru> To: Kris Kennaway <kris@obsecurity.org> Cc: freebsd-hackers@freebsd.org Subject: Re: numbers don't lie ... Message-ID: <20060920123940.W63482@woozle.rinet.ru> In-Reply-To: <20060919173421.GA45928@xor.obsecurity.org> References: <200609141232.k8ECWTXj045191@lurza.secnetix.de> <20060919160511.T33371@woozle.rinet.ru> <20060919173421.GA45928@xor.obsecurity.org>
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On Tue, 19 Sep 2006, Kris Kennaway wrote:
KK> > OF> Because buildworld is I/O-bound on systems with sufficiently
KK> > OF> fast processors.
KK> > OF>
KK> > OF> Try putting the contents of /usr/src into a RAM disk and
KK> > OF> repeat the benchmark. The numbers might look a little
KK> > OF> different then. Of course, you should have sufficient RAM
KK> > OF> in the machines -- If they're going to swap to the disks,
KK> > OF> your benchmark won't be happy.
KK> > OF>
KK> > OF> I think putting /usr/obj onto a RAM disk is _not_ necessary
KK> > OF> because of soft-updates, so the processes shouldn't block
KK> > OF> on writes.
KK> >
KK> > My experiments show that if you have enough memory to host radmdrive for
KK> > /usr/src you'd better leave it for caching - there were no statistically
KK> > meaningful performance difference, at least on machines with 1G+ RAM.
KK>
KK> Really? My measurements show the opposite (on a system with 16GB of
KK> RAM).
My last test on amd64/dualcore with 4G of RAM and -j4 shows
(buildworld+buildkernel):
==> /tmp/buildlog <==
1996.45 real 3032.94 user 624.83 sys
Script done on Tue Sep 19 14:44:54 2006
==> /tmp/buildlog.md <==
1957.45 real 3033.93 user 585.78 sys
Script done on Tue Sep 19 15:20:42 2006
Second one was with 512M/4k/512 swap-backed md, the former with /usr/src on the
gmirror'ed pair of SATAs.
Sincerely,
D.Marck [DM5020, MCK-RIPE, DM3-RIPN]
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*** Dmitry Morozovsky --- D.Marck --- Wild Woozle --- marck@rinet.ru ***
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