Re: [2.6.16-gitX] heavy performance regression in ipw2200 wireless driver

[Alessandro Suardi]

On 3/23/06, Andrew Morton <akpm@xxxxxxxx> wrote:
> "Alessandro Suardi" <alessandro.suardi@xxxxxxxxx> wrote:
> >
>
> Pleeeeze try to cc the right people.

Sorry about that - should probably defer bug reporting to times
 when I'm actually supposed to be awake (2:20am doesn't fit
 the bill obviously :| )

> > Driver - or firmware ? Don't know - since the new git snapshots run
> >  1.1.1 which requires newer firmware from http://ipw2200.sourceforge.net.
> >
> > Symptom -> my new FC5 partition with 2.6.16-git kernels connects via
> >  VNC viewer to my bittorrent box over wireless (ipw2200 to a D-Link
> >  G604T router/AP); Dell D610 runs FC5, BT box is a K7-800 running
> >  FC3 with a 2.6.16-rc5-git8 kernel (15+ days uptime...).
> >
> > I also run Firefox on the bittorrent box; noticed today (2.6.16-git5) that
> >  the screen refresh of pages with images was from time to time very
> >  slow (close to unusable).
> >
> > Rebooted into my FC4 partition with a 2.6.16 kernel, everything much
> >  snappier. So I ran a scp test from my BT server to the laptop, three
> >  times in a row the same file - a 38MB .flac with the laptop in the same
> >  physical position (ie, no signal variation). Results...
> >
> > FC5 - 2.6.16-git3:
> >
> > [asuardi@donkey melua_2004-09-23_Berlin]$ scp KM_9-23-04_17_The\
> > Closest\ Thing\ to\ Crazy.flac 192.168.1.8:/tmp
> > asuardi@xxxxxxxxxxx's password:
> > KM_9-23-04_17_The Closest Thing to Crazy.flac 100%   38MB 971.3KB/s   00:40
> > [asuardi@donkey melua_2004-09-23_Berlin]$ scp KM_9-23-04_17_The\
> > Closest\ Thing\ to\ Crazy.flac 192.168.1.8:/tmp
> > asuardi@xxxxxxxxxxx's password:
> > KM_9-23-04_17_The Closest Thing to Crazy.flac 100%   38MB   1.3MB/s   00:29
> > [asuardi@donkey melua_2004-09-23_Berlin]$ scp KM_9-23-04_17_The\
> > Closest\ Thing\ to\ Crazy.flac 192.168.1.8:/tmp
> > asuardi@xxxxxxxxxxx's password:
> > KM_9-23-04_17_The Closest Thing to Crazy.flac 100%   38MB 626.7KB/s   01:02
> >
> >
> > FC4 - 2.6.16:
> >
> > [asuardi@donkey melua_2004-09-23_Berlin]$ scp KM_9-23-04_17_The\
> > Closest\ Thing\ to\ Crazy.flac 192.168.1.8:/tmp
> > asuardi@xxxxxxxxxxx's password:
> > KM_9-23-04_17_The Closest Thing to Crazy.flac 100%   38MB   1.5MB/s   00:25
> > [asuardi@donkey melua_2004-09-23_Berlin]$ scp KM_9-23-04_17_The\
> > Closest\ Thing\ to\ Crazy.flac 192.168.1.8:/tmp
> > asuardi@xxxxxxxxxxx's password:
> > KM_9-23-04_17_The Closest Thing to Crazy.flac 100%   38MB   1.7MB/s   00:23
> > [asuardi@donkey melua_2004-09-23_Berlin]$ scp KM_9-23-04_17_The\
> > Closest\ Thing\ to\ Crazy.flac 192.168.1.8:/tmp
> > asuardi@xxxxxxxxxxx's password:
> > KM_9-23-04_17_The Closest Thing to Crazy.flac 100%   38MB   1.7MB/s   00:22
> >
> > Bottom line - old driver has better performance than the new one,
> >  but most noticeably delivers consistent performance.
> >
> > I will be available for testing starting Thursday 30th as I'll be on
> >  the road since then. Of course if the problem is identified and
> >  fixed earlier, I won't cry ;)
>
> Well.  It's not a huge regression.  It's a 50%ish regression.  We've done
> worse ;)

That scp test shows 50%ish - but that was a quickie. The VNC
 client even reported a 719Kbps throughput down from the more
 usual 11500Kbps it starts off with. The first scp I tried when the
 sluggishness was intolerable was going at 200KB/s - which
 shows the problem can easily get in the neighborhood of an
 order of magnitude.

Thanks,

--alessandro

 "Dreamer ? Each one of us is a dreamer. We just push it down deep because
   we are repeatedly told that we are not allowed to dream in real life"
     (Reinhold Ziegler)
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