From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Raghavendra Koushik" Subject: RE: [PATCH 2.6.12.1 5/12] S2io: Performance improvements Date: Fri, 8 Jul 2005 11:16:14 -0700 Message-ID: <200507081816.j68IGIKP024269@guinness.s2io.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: , , , , , Return-path: To: "'Arthur Kepner'" In-Reply-To: Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org 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@sgi.com] > Sent: Friday, July 08, 2005 8:31 AM > To: Raghavendra Koushik > Cc: jgarzik@pobox.com; netdev@oss.sgi.com; > netdev@vger.kernel.org; ravinandan.arakali@neterion.com; > leonid.grossman@neterion.com; rapuru.sriram@neterion.com > 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 >