Date: Fri, 31 Mar 2006 09:19:35 +0200 From: "Eric" <ericd@free.fr> To: "Lucas Holt" <luke@foolishgames.com> Cc: freebsd-smp@freebsd.org Subject: Re: Low perf with smp Message-ID: <01a901c65493$77ad2740$65fd24c0@Eric> References: <009301c65418$cc029f30$65fd24c0@Eric> <64659004-E643-4044-AAED-076E0CC91977@foolishgames.com>
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Thanks a lot Lucas. What's sound so strange to me is that there we so much difference 30sec=> 54 sec simply by activating smp in kernel. But I will search on this way and see if it don't come from mysql. I will send you issue. Eric. ----- Original Message ----- From: "Lucas Holt" <luke@foolishgames.com> To: "Eric" <ericd@free.fr> Cc: <freebsd-smp@freebsd.org> Sent: Friday, March 31, 2006 2:00 AM Subject: Re: Low perf with smp > As i recall, mysql under FreeBSD 4.x used a userland threads library. > That means its only capable of being scheduled on 1 cpu at a time and > each thread is part of one process. I don't think SMP will help you much > in this case. There have been a number of threads on some of the lists > (hacker@ ?) in the last few months about MySQL performance indicating it > might have something to do with the timer, etc. It might be worth > looking into. > > Some people have stated that FreeBSD 5 and 6 are slower with disk io, > etc. Plus you've got a raid 1 mirror which will slow down writes. 6.1 > also has a reported issue with the 4bsd scheduler performance. Maybe > thats part of the problem? > > On Mar 30, 2006, at 11:41 AM, Eric wrote: > >> Mail NETvigieHi all, >> >> I buy a new DELL PowerEdge 1850 with Bi-Xeon 2.8GHZ/2*2MB Dual Core >> 800FSB processor, 2Go DDR2 RAM, PERC4di RAID controller with 2 SCSI U320 >> 15.000tpm 36Go hdd on RAID1. >> >> I install on it Freebsd 6.0, apache 2.2.0 and mysql 4.1.18 and compare >> performance with : >> OLD PowerEDge with only simple Bi-Xeon 3.0 GHZ and freebsd 4.11. >> >> The test is simple mysql query done by php script. >> >> Result is that test is two time slower with freebsd 6.0 and dual- core >> than with old server. >> I try with and without smp and threaded kernel and results are same. >> I came back to Generic kernel to see if it come from my kernel >> configuration but result was same. >> >> I then though it come from server and try to upgrade an other one and >> have same result. >> I then think it come from 6.0 and try with 6.1 beta4 and see same result >> I then downgrad to 4.11 without smp and then find good perfs. >> So I just add to 4.11 generic kernel : >> options SMP # Symmetric MultiProcessor >> Kernel >> options APIC_IO # Symmetric (APIC) I/O >> >> And then perf go back down from 30secondes to 54 sec. >> I search a lot on internet and try with this : sysctl >> machdep.cpu_idle_hlt=0 >> But result is same. >> >> When doing whith smp top it's just as mysql have to wait to have cpu. >> During 10,20 sec it just go to 2,4% then grow. Without smp it grow very >> quickly. >> >> Does anyone know what's go wrong and what do I have to do to have same >> perf with smp than without? >> >> Thanks, >> >> Eric. >> >> >> _______________________________________________ >> freebsd-smp@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-smp >> To unsubscribe, send any mail to "freebsd-smp-unsubscribe@freebsd.org" > > > Lucas Holt > Luke@FoolishGames.com > ________________________________________________________ > FoolishGames.com (Jewel Fan Site) > JustJournal.com (Free blogging) > FoolishGames.net (Enemy Territory site) > > > _______________________________________________ > freebsd-smp@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-smp > To unsubscribe, send any mail to "freebsd-smp-unsubscribe@freebsd.org" >
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