Jim Magee writes:
On Thursday, October 3, 2002, at 05:39 PM, Andrew Gallatin wrote:
% pwd
/private/var/tmp
% cp /home/gallatin/hacks/LMbench/bin/powerpc-apple-darwin1.4/lat_proc
.
% ./lat_proc fork
Process fork+exit: 7577.0000 microseconds
% /home/gallatin/hacks/LMbench/bin/powerpc-apple-darwin1.4/lat_proc
fork
Process fork+exit: 7529.0000 microseconds
Have you tried it from an account that has a local home directory? NFS
does such weird things to performance numbers that I like to keep it
completely out of the mix (unless I'm trying to benchmark NFS).
Interestingly, there were significant NFS changes in those timeframes.
Earlier I replied privately to Jim that an account with a local home forked faster than an account with an NFS home... Well, its all due to a difference in the local and NFS .cshrc. The NFS .cshrc contains the line 'unlimit stacksize' I guess Darwin must REALLY unlimit the stacksize to something obscene. From the appended few datapoints, it looks like the fork perf is directly proportional to the stacksize limit. At any rate, removing that line (conditional on darwin-powerpc*), gets fork performance back to what I remember it being a long time ago. (probably before I needed to add that line for nameless OS which artificially limits stacksize too low). The install script that prompted the question by taking over 3 minutes is now down to 20 seconds (within an acceptable factor of 2 of linux). I'm willing to plead to pilot error on this one. But it does seem rather strange that upping a *limit* will wreak havok with fork performance. Are process' stacks pre-allocated up to the limit or something? Drew [g4:~] drew% limit cputime unlimited filesize unlimited datasize unlimited stacksize 512 kbytes coredumpsize 0 kbytes memoryuse unlimited descriptors 256 memorylocked unlimited maxproc 100 [g4:~] drew% ~gallatin/hacks/LMbench/bin/powerpc-apple-darwin6.0/lat_proc fork Process fork+exit: 1648.2500 microseconds [g4:~] drew% limit stacksize 16384k [g4:~] drew% ~gallatin/hacks/LMbench/bin/powerpc-apple-darwin6.0/lat_proc fork Process fork+exit: 4530.0000 microseconds [g4:~] drew% exit logout Connection to g4.sw closed. <3:15pm>whisper/gallatin:~>ssh g4.sw -l drew Last login: Mon Oct 7 15:14:36 2002 from 172.31.193.10 Welcome to Darwin! [g4:~] drew% unlimit stacksize [g4:~] drew% ~gallatin/hacks/LMbench/bin/powerpc-apple-darwin6.0/lat_proc fork [g4:~] drew% limit stacksize 8k Process fork+exit: 7648.0000 microseconds [g4:~] drew% ~gallatin/hacks/LMbench/bin/powerpc-apple-darwin6.0/lat_proc fork Process fork+exit: 1574.7500 microseconds _______________________________________________ darwin-kernel mailing list | darwin-kernel@lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.
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Andrew Gallatin