Re: Switch pfil(9) to rmlocks

Max Laier wrote:
On Friday 23 November 2007, Robert Watson wrote:
> On Fri, 23 Nov 2007, Max Laier wrote:
> > attached is a diff to switch the pfil(9) subsystem to rmlocks, which
> > are more suited for the task. I'd like some exposure before doing
> > the switch, but I don't expect any fallout. This email is going
> > through the patched pfil already - twice.
>
> Max,
>
> Have you done performance measurements that show rmlocks to be a win in
> this scenario? I did some patchs for UNIX domain sockets to replace
> the rwlock there but it appeared not to have a measurable impact on SQL
> benchmarks, presumbaly because the read/write blend wasn't right and/or
> that wasnt a significant source of overhead in the benchmark. I'd
> anticipate a much more measurable improvement for pfil, but would be
> interested in learning how much is seen?

I had to roll an artificial benchmark in order to see a significant change (attached - it's a hack!).

Using 3 threads on a 4 CPU machine I get the following results:
null hook: ~13% +/- 2
mtx hook: up to 40% [*]
rw hook: ~5% +/- 1
rm hook: ~35% +/- 5

Is that 13%/5%/35% faster or slower or improvement or degradation?
If "rw hook" (using rwlock like we have today?) is 5%, whas is the baseline?

I'm expecting that at least one of these should be a 0%...

Darren

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Relevant Pages

  • Re: Switch pfil(9) to rmlocks
    ... > On Fri, 23 Nov 2007, Max Laier wrote: ... >> the switch, but I don't expect any fallout. ... > Have you done performance measurements that show rmlocks to be a win in ... I had to roll an artificial benchmark in order to see a significant change. ...
    (freebsd-current)
  • Re: Switch pfil(9) to rmlocks
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    (freebsd-current)
  • Re: Switch pfil(9) to rmlocks
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    (freebsd-net)
  • Re: Switch pfil(9) to rmlocks
    ... > Max Laier wrote: ... >>> Have you done performance measurements that show rmlocks to be a ... All numbers above are gain with rmlocks i.e. rmlocks are faster in all scenarios. ... Every hook has a DELAYand a lock/unlock call around it of the respective lock type. ...
    (freebsd-current)
  • Re: Switch pfil(9) to rmlocks
    ... > Max Laier wrote: ... >>> Have you done performance measurements that show rmlocks to be a ... All numbers above are gain with rmlocks i.e. rmlocks are faster in all scenarios. ... Every hook has a DELAYand a lock/unlock call around it of the respective lock type. ...
    (freebsd-net)