Subject: newpipes
To: None <>
From: Jason R. Fink <>
List: tech-kern
Date: 05/14/2001 15:14:32
Last weekend I was asked if I could try out a couple different 
snapshots between 1.5.1 and -current to find out if and when there
was a performance drop in pipes (without newpipes being added).

The results of just 2 tries are up at

Here is a quick summary, I grabbed 20010504-UTC and 20010502-UTC
since prior to that my tree was at 20010508-UTC (I basically 
half split).

sources from 20010504-UTC

Pipe bandwidth: 90.30 MB/sec
Pipe bandwidth: 90.39 MB/sec
Pipe bandwidth: 91.32 MB/sec

sources from 20010502-UTC

Pipe bandwidth: 88.07 MB/sec
Pipe bandwidth: 87.76 MB/sec
Pipe bandwidth: 88.92 MB/sec

I noticed that these are very close and the 0504 results are close
to the results of 1.5.1. So I decided to do some random testing
on the 0502 kernel. I waited up to 20 minutes between some and a few
seconds with others:

Pipe bandwidth: 87.65 MB/sec
Pipe bandwidth: 88.92 MB/sec
Pipe bandwidth: 78.00 MB/sec
Pipe bandwidth: 83.59 MB/sec

I went forward to 0508 then back to the 1.5.1 kernel and saw similar
results - in short I don't think there is a problem. It only looked 
that way because I took only 3 very close together measurements each
time. I reckon it was better safe than sorry.