From mboxrd@z Thu Jan 1 00:00:00 1970 From: Elad Lahav Subject: Re: Performance degradration 2.6.25->2.6.26 Date: Fri, 12 Sep 2008 10:58:37 -0400 Message-ID: <48CA839D.308@uwaterloo.ca> References: <489C0F2C.9040101@users.sourceforge.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: e1000-devel@lists.sourceforge.net, netdev@vger.kernel.org, Elad Lahav To: "Brandeburg, Jesse" Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: e1000-devel-bounces@lists.sourceforge.net Errors-To: e1000-devel-bounces@lists.sourceforge.net List-Id: netdev.vger.kernel.org >> HyperThreading, for a total of 4 logical processors, and 4 Intel Gigabit >> NICs on a PCI 64/66 bus (82546EB). In the experiments, I am pinning >> four sending processes (one per NIC) to logical processors 0 and 2, and >> the NIC interrupts to logical processors 1 and 3, such that interrupts >> are serviced by the sibling logical processor of the one sending the >> packets. I have used both the driver that comes with the Linux kernel >> (7.3.20-k2-NAPI), as well as a more recent one (7.6.15.5). I believe I have found the problem, and it has nothing to do with the driver. Up to the latest kernel, logical processors on the same chip had sequential CPU IDs. So CPU 0 and CPU 1 were two logical processors on the first physical one, 2 and 3 on the second physical one, etc. It seems that now this ordering has changed. I was running my experiments on logical processors 0 and 2, assuming they were on different physical processors, when, in fact, they were sharing the same one. When pinning the processes to logical processor 0 and 1, I get at least as good a performance as I do on previous kernels. Thanks, Elad ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/