Re: Testing the effects of the low latency patch

From: J Sloan (jjs@lexus.com)
Date: Thu Jan 24 2002 - 20:14:45 EST


Andrew Morton wrote:

>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?
>
Yes, the stock kernel is much improved from
say 6 months ago. I will take a look at the
kernel that shipped with my distro just for
giggles as well...

>>
>>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.
>
Yes this smells like a statistical anomaly -

Will run mulitple tests tonight and see if
there's an actual trend there or just a
blip on the screen.

Joe

>

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