From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arthur Kepner Subject: RE: [PATCH 2.6.12.1 5/12] S2io: Performance improvements Date: Fri, 8 Jul 2005 08:31:21 -0700 (PDT) Message-ID: References: <200507080106.j6816NKP022996@guinness.s2io.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: jgarzik@pobox.com, netdev@oss.sgi.com, netdev@vger.kernel.org, ravinandan.arakali@neterion.com, leonid.grossman@neterion.com, rapuru.sriram@neterion.com Return-path: To: Raghavendra Koushik In-Reply-To: <200507080106.j6816NKP022996@guinness.s2io.com> Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org 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