BSD vs Linux Threads

[Martin Hepworth]

On 12/9/05, Greg 'groggy' Lehey <grog at 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 the
> >> 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 also
run on Solaris etc I wonder it performs on the tradition commericial Unix
variants?

--
martin