Re: Default cache_hot_time value back to 10ms

[Andrew Morton]

"Chen, Kenneth W" <kenneth.w.chen@xxxxxxxxx> wrote:
>
> Andrew Morton wrote on Tuesday, October 05, 2004 9:51 PM
>  > > Nick Piggin <nickpiggin@xxxxxxxxxxxx> wrote:
>  > >  I'd say it is probably too low level to be a useful tunable (although
>  > >  for testing I guess so... but then you could have *lots* of parameters
>  > >  tunable).
>  >
>  > This tunable caused an 11% performance difference in (I assume) TPCx.
>  > That's a big deal, and people will want to diddle it.
>  >
>  > If one number works optimally for all machines and workloads then fine.
>  >
>  > But yes, avoiding a tunable would be nice, but we need a tunable to work
>  > out whether we can avoid making it tunable ;)
>  >
>  > Not that I'm soliciting patches or anything.  I'll duck this one for now.
> 
>  Andrew, can I safely interpret this response as you are OK with having
>  cache_hot_time set to 10 ms for now?

I have a lot of scheduler changes queued up and I view this change as being
not very high priority.  If someone sends a patch to update -mm then we can
run with that, however Ingo's auto-tuning seems a far preferable approach.

>  And you will merge this change for 2.6.9?

I was not planning on doing so, but could be persuaded, I guess.

It's very, very late for this and subtle CPU scheduler regressions tend to
take a long time (weeks or months) to be identified.
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