Re: Scheduling latencies news: less RAM = less latency

Roger Larsson (nra02596@norran.net)
Sun, 01 Aug 1999 01:23:51 +0200


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Mark Hahn wrote:
>
> > And it was run on a 512 MB Dual Pentium(!) system.
>
> hmm, what chipset and motherboard cache does this system have?
> if the system's caching was broken (as all P5 systems were, to some
> extent), that might explain the inordinately slow behavior of some
> kernel functions. as I recall, the HX chipset was the only multi-P5
> chipset, and how much it could L2 cache depended on bios settings,
> the size of L2, and width of installed tag sram chips.
>
> actually, it would be useful to know which P5 you are using
> (P54c/mmx, with larger L1?) and to verify that both L1 and L2
> are enabled on your system...

Forget the 90 ms in d_lookup I thought I knew what readprofile did...

But I do know what my patch does and I get even longer latencies.
As an example at netscape start up... 129 ms, ( > 50 ms are rare)
In this case it is not what one function takes, it's more like
time from need_resched (a higher prio. process wanting the CPU)
to actual rescheduling.
See included data, normal start up, nothing special...

(generated with
dmesg | grep Latency > latency.dmesg
)

I am keeping the patch private (anyone get it on request) until
the verdict is in.

/RogerL
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Latency 20ms PID 352 PCs C01463EC % find
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