Re: Latency tests with 2.6.12-rc1

Ingo Molnar
2005-03-19T07:09:14Z

* Lee Revell <rlrevell@joe-job.com> wrote:

> I did the same quick latency tests with 2.6.12-rc1 that I posted about
> for 2.6.11 a few weeks ago.
>
> 2.6.12-rc1 is significantly better than 2.6.11. Running JACK at 64
> frames (1.3 ms) works very well. I was not able to produce xruns even
> with "dbench 64", which slows the system to a crawl. With 2.6.11, I
> could easily produce xruns with much lighter loads.
>
> It would appear that the latency issues related to the 4 level page
> tables merge have been resolved.

great! The change in question is most likely the copy_page_range() fix
that Hugh resurrected:

ChangeSet 1.2037, 2005/03/08 09:26:46-08:00, hugh@veritas.com

[PATCH] copy_pte_range latency fix

Ingo's patch to reduce scheduling latencies, by checking for lockbreak in
copy_page_range, was in the -VP and -mm patchsets some months ago; but got
preempted by the 4level rework, and not reinstated since. Restore it now
in copy_pte_range - which mercifully makes it easier.

are the ext3 related latencies are gone as well - or are you working it
around by not using data=ordered?

Ingo