low(er) disk performance with sched_4bsd then with sched_ule
lehmann at ans-netz.de
Wed Sep 14 15:00:41 PDT 2005
Joseph Koshy wrote:
> On -current you could use hwpmc and pmcstat to get a quick idea
> of what is happening to the system:
> 1. # kldload hwpmc
> You'll need a kernel compiled with options HWPMC_HOOKS.
> 2. # pmcstat -S instructions -c 1 -S instructions -O /tmp/ule.out dd if=...etc
> This command line instructs pmcstat to setup sampling
> on both CPUs 0 & 1.
> 3. # pmcstat -R /tmp/ule.out -g
> Convert the hwpmc(4) log to gprof gmon.out profiles.
> 4. # gprof -l /boot/kernel/kernel
> ./k8-fr-retired-x86-instructions/kernel.gmon > gprof.ule
> Repeat for the 4BSD case and compare.
> Current has a few bug fixes that need to be merged to 6.0;
> but you should get by in a pinch by copying over the content
> of sys/dev/hwpmc/ and usr.sbin/pmcstat/ to a 6.x tree
> and rebuilding.
I did this now for bs=64k count=32000. The results are here:
Hope this helps
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