I'll include this fix in the next patch that incorporates
any other review comments coming my way.. Thanks for pointing
it out.
-Koushik
> -----Original Message-----
> From: Arthur Kepner [mailto:akepner@xxxxxxx]
> Sent: Friday, July 08, 2005 8:31 AM
> To: Raghavendra Koushik
> Cc: jgarzik@xxxxxxxxx; netdev@xxxxxxxxxxx;
> netdev@xxxxxxxxxxxxxxx; ravinandan.arakali@xxxxxxxxxxxx;
> leonid.grossman@xxxxxxxxxxxx; rapuru.sriram@xxxxxxxxxxxx
> Subject: RE: [PATCH 2.6.12.1 5/12] S2io: Performance improvements
>
> On Thu, 7 Jul 2005, Raghavendra Koushik wrote:
>
> > ....
> > On an Altix machine I believe the readq was necessary to flush
> > the PIO writes. How long did you run the tests? I had seen
> > in long duration tests that an occasional write
> > (TXDL control word and the address) would be missed and the xmit
> > Get's stuck.
> >
>
> The most recent tests I did used pktgen, and they ran for a total
> time of ~.5 hours (changing pkt_size every 30 seconds or so). The
> pktgen tests and other tests (like nttcp) have been run
> several times,
> so I've exercised the card for a total of several hours without
> any problems.
>
> >
> > >
> > > FWIW, I've done quite a few performance measurements with
> the patch
> > > I posted earlier, and it's worked well. For 1500 byte
> mtus throughput
> > > goes up by ~20%. Is even the mmiowb() unnecessary?
> > >
> >
> > Was this on 2.4 kernel because I think the readq would not have a
> > significant impact on 2.6 kernels due to TSO.
> > (with TSO on the number of packets that actually enter the
> > Xmit routine would be reduced apprx 40 times).
> > .....
>
> This was with a 2.6 kernel (with TSO on). PIO reads are pretty
> expensive on Altix, so eliminating them really helps us.
>
> For big mtus (>=4KBytes) the benefit of replacing the readq()
> with mmiowb() in s2io_xmit() is negligible.
>
> --
> Arthur
>
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