Re: Testing the effects of the low latency patch

From: Andrew Morton (akpm@zip.com.au)
Date: Thu Jan 24 2002 - 20:03:29 EST


J Sloan wrote:
>
> I had earlier posted reports about the low latency patch in terms
> that are too subjective - e.g. saying that "quake 3 arena feels much
> smoother and I frag a lot more" isn't the kind of hard statistical
> evidence demanded by some. I have attempted to quanitify the latency
> differences in one of the workloads where I see and feel a difference.

mm. Numbers. Nice.

>
> 2.4.18-pre6+tux+nfs-fixes
> -------------
> ...
> 7.6 1
> 7.8 1
> 21.1 1

This is the stock kernel. In twenty minutes you suffered
precisely *one* scheduling overrun which is perceptible
by a human. The rest are much shorter than your monitor's
refresh interval. Interesting, yes?

These results are better than the ones I normally measure.

> ...
> The dbench results:
>
> 2.4.18-pre6+tux+nfs-fixes
> ---------------------------------
> ...
> Throughput 48.9432 MB/sec (NB=61.179 MB/sec 489.432 MBit/sec) 16 procs
> ...
>
> 2.4.18-pre6+tux+nfs-fixes + low latency patch
> ---------------------------------
> ...
> Throughput 106.361 MB/sec (NB=132.951 MB/sec 1063.61 MBit/sec) 16 procs
> ...

Now that's odd.

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