Date: Sat, 10 Dec 2005 11:48:57 +0000 From: Martin Hepworth <maxsec@gmail.com> Cc: freebsd-questions@freebsd.org Subject: Re: BSD vs Linux Threads Message-ID: <72cf361e0512100348s6c1e86cfv23153da1a9f4078c@mail.gmail.com> In-Reply-To: <20051209012022.GE80362@wantadilla.lemis.com> References: <4B3EE484EEA4F344BBB62F8316489986554680@corpsrv.RedMoon.local> <LOBBIFDAGNMAMLGJJCKNOEOGFCAA.tedm@toybox.placo.com> <20051209012022.GE80362@wantadilla.lemis.com>
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On 12/9/05, Greg 'groggy' Lehey <grog@freebsd.org> wrote: > > [resequenced] > > On Friday, 2 December 2005 at 22:27:51 -0800, Ted Mittelstaedt wrote: > > On Thursday, December 01, 2005 12:36 PM, Cody Holland wrote: > >> > >> Well in the past it was stated that on a MySQL server installed using > >> Linux threads was faster than using the native BSD threads. I'm in th= e > >> process of building a new MySQL 5 server with FreeBSD 5.4 and was > >> wanting to know if using the Linux threads was still faster. > > > > It probably is because mysql is optimized for the Linux threading > > implementation. > > Also keep in mind that freebsd filesystems are mounted async by default= , > > not sync by default like Linux, as a result FreeBSD always does worse > > in these stupid bakeoffs you read about in the trade rags. > > Somebody else has pointed out that this was stated the wrong way > round. But what we've seen so far is probably not related to the way > the file systems are mounted. > > > You can install the linux threading package under FreeBSD's linux > > emulation and try it that way. > > I don't think this is a useful option. Linuxthreads might be, though. > > > Keep in mind also that you are talking minute performance > > differences on the newest multi-gigahertz systems. > > It would be nice if this were true. We've seen claims of performance > differences in the order of 3:1. > > > Furthermore I will point out that unless your database is smaller > > than physical memory of the server, then the argument between mysql > > threading and non-threading is a completely moot issue since the > > hits to the disk will be the bottleneck. > > Many database systems are CPU-bound. Well yes they are, normally due to poor or zero tuning of the queries etc....tuning RDBMS's is a science in itself andcan be quite specific tothe RDBMS in question MySQL has identified that there are some serious issues with FreeBSD > at the moment. As somebody with a foot in both camps, I'm keeping an > open mind about where the problem is, but certainly the threading > libraries are an issue. I wish I could make a specific > recommendation. COuld well be that the mysql is optimised for lunix threading. Given it als= o run on Solaris etc I wonder it performs on the tradition commericial Unix variants? -- martin
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