roam at ringlet.net
Tue Dec 13 05:42:34 PST 2005
On Fri, Dec 09, 2005 at 08:05:37PM -0800, Jin Guojun [VFFS] wrote:
> David Xu wrote:
> >Gustavo A. Baratto wrote:
> >>Since the last post just had freebsd numbers, I'm re-posting it
> >>Linux as well. Both linux and freebsd numbers were taken from the
> >>same box:
> >Can you try TSC timer on FreeBSD ? someone reported that using TSC
> >timer boosts performance of super-smack significantly.
> >David Xu
> "TSC" can be a few 100 times faster than gettimeofday(), but one needs
> to know
> how to calibrate and convert it to timer because TSC is counter, not timer.
> Also, if FreeBSD uses TSC to compare with Linux using gettimeofday,
> it does not sound a fun.
> gettimeofday is a very expensive function on all systems.
> tells how much it costs on some common systems, especially FreeBSD and
> So, if both systems use gettimeofday, then slow may be somewhere else.
Errrr... I think David might have meant that the original poster should
simply set kern.timecounter.hardware to 'TSC', not i8254 or something
else. This would not change whether MySQL uses gettimefday() or not,
it would simply change the in-kernel method of obtaining the actual
time of day - at least that's how I understand it :)
Peter Pentchev roam at ringlet.net roam at cnsys.bg roam at FreeBSD.org
PGP key: http://people.FreeBSD.org/~roam/roam.key.asc
Key fingerprint FDBA FD79 C26F 3C51 C95E DF9E ED18 B68D 1619 4553
This sentence every third, but it still comprehensible.
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