Date: Thu, 01 Feb 2007 12:02:20 -0800 From: Julian Elischer <julian@elischer.org> To: Andrew Gallatin <gallatin@cs.duke.edu> Cc: FreeBSD Current <current@freebsd.org> Subject: Re: lock contention etc. Message-ID: <45C2474C.3080909@elischer.org> In-Reply-To: <17858.17285.523377.837244@grasshopper.cs.duke.edu> References: <45C24113.7000608@elischer.org> <17858.17285.523377.837244@grasshopper.cs.duke.edu>
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Andrew Gallatin wrote: > Julian Elischer writes: > > I'm guessing that the extra system time represents a lot of > > contention somewhere. > > > > What is the best way to get actual numbers on this? > > The Dtrace lockstat tool is designed for this, and I've used it to > track down contention like this on Solaris. It seems to be on the > TODO list for the FreeBSD Dtrace port at > http://people.freebsd.org/~jb/dtrace/todo.html. I wonder how soon it > will arrive.. It is one of the things that I'm most looking forward > to. > > Drew I just realised that since this is an HTT machine the massive increase in user and system times between -j2 and -j4 is probably due to every thing running slower but over twice as many cpus.. The increase between -j1 and -j2 is more relevant and interesting I think. make -j 2 buildworld 2465.10 real 2958.94 user 1918.64 sys 2463.97 real 2968.43 user 1910.65 sys 2472.13 real 2978.64 user 1912.80 sys 2582.83 real 2965.51 user 2047.19 sys make -j 4 buildworld 2262.88 real 4322.31 user 3333.58 sys 2255.88 real 4330.32 user 3319.48 sys 2256.09 real 4318.84 user 3336.57 sys 2257.63 real 4338.34 user 3313.07 syshome | help
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