Date: Tue, 26 Sep 2006 09:48:39 +0400 (MSD) From: Dmitry Morozovsky <marck@rinet.ru> To: Dag-Erling =?iso-8859-1?Q?Sm=F8rgrav?= <des@des.no> Cc: freebsd-hackers@freebsd.org, Kris Kennaway <kris@obsecurity.org> Subject: Re: numbers don't lie ... Message-ID: <20060926094720.Q25959@woozle.rinet.ru> In-Reply-To: <86hcywrxkg.fsf@dwp.des.no> References: <200609141232.k8ECWTXj045191@lurza.secnetix.de> <20060919160511.T33371@woozle.rinet.ru> <20060919173421.GA45928@xor.obsecurity.org> <20060920123940.W63482@woozle.rinet.ru> <86hcywrxkg.fsf@dwp.des.no>
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On Mon, 25 Sep 2006, Dag-Erling Sm?rgrav wrote: DS> > > > My experiments show that if you have enough memory to host radmdrive for DS> > > > /usr/src you'd better leave it for caching - there were no statistically DS> > > > meaningful performance difference, at least on machines with 1G+ RAM. DS> > > Really? My measurements show the opposite (on a system with 16GB of DS> > > RAM). DS> > My last test on amd64/dualcore with 4G of RAM and -j4 shows DS> > (buildworld+buildkernel): DS> > DS> > ==> /tmp/buildlog <== DS> > 1996.45 real 3032.94 user 624.83 sys DS> > Script done on Tue Sep 19 14:44:54 2006 DS> > DS> > ==> /tmp/buildlog.md <== DS> > 1957.45 real 3033.93 user 585.78 sys DS> > Script done on Tue Sep 19 15:20:42 2006 DS> > DS> > Second one was with 512M/4k/512 swap-backed md, the former with /usr/src on the DS> > gmirror'ed pair of SATAs. DS> DS> Seems to me that your own numbers contradict you. You saved about 40 DS> seconds (2%) by keeping /usr/src in a ram disk. Well, maybe I did used wrong wording (2% is statistically meaningful), but for me 2% is not worth all the efforts needed to organize ram disk infrastructure... Sincerely, D.Marck [DM5020, MCK-RIPE, DM3-RIPN] ------------------------------------------------------------------------ *** Dmitry Morozovsky --- D.Marck --- Wild Woozle --- marck@rinet.ru *** ------------------------------------------------------------------------
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