Re: MP Perfomance

On Fri, Mar 19, 2004 at 07:50:43PM +1100, Simon Burge wrote:
> "Zafer Aydogan" wrote:
> 
> There is more kernel overhead in an MP kernel as more things need to be
> locked, etc.  For a single non-threaded program, you probably will get
> better performance from a UP kernel.
there a also some advantages, for example if your mysql process get 99% of
one cpu, the second will be only 1-2%, and programs that runs on the second
cpu will work quickly.
4 ex.: I have mail server 2x400Mhz, 512MB ram, with NetBSD -current, it is runing postfix
with a lot of pcre stuff, also runing mysql for virtual mail users, (imap|imaps)/(pop3|pop3s).
with the same software configuration, I have tested it on that MP server
and one with UP (1.2Ghz, 512 MB RAM): when sending 10000 mails/s, the UP
load averages runs in to about 140 !? :), and with MP - 70-80,
and sends out mail after 5-7 minutes, UP - 15-20 minutes. So ... :)

> Did you try "make -j N" for some value of N > 1?  I use N = 2*ncpus
> here - that seems to be about the sweet spot.
yes, this option does job very well :)

> In general, it's faster :)
and as far as I calculated - faster a lot.

-- 
Sincerely,
Simas Mockevicius

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