From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: RFC: Nagle latency tuning Date: Mon, 22 Sep 2008 22:30:42 +0200 Message-ID: <20080922203042.GY25711@one.firstfloor.org> References: <48C6C300.4050102@redhat.com> <20080909.125934.150042096.davem@davemloft.net> <20080922.034933.119934091.davem@davemloft.net> <20080922.040912.193700258.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: csnook@redhat.com, andi@firstfloor.org, rick.jones2@hp.com, netdev@vger.kernel.org To: David Miller Return-path: Received: from one.firstfloor.org ([213.235.205.2]:60784 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751031AbYIVUZ4 (ORCPT ); Mon, 22 Sep 2008 16:25:56 -0400 Content-Disposition: inline In-Reply-To: <20080922.040912.193700258.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, Sep 22, 2008 at 04:09:12AM -0700, David Miller wrote: > From: David Miller > Date: Mon, 22 Sep 2008 03:49:33 -0700 (PDT) > > > I'll try to figure out why Andi's patch doesn't behave as expected. > > Andi's patch uses proc_dointvec_jiffies, which is for sysctl values > stored as seconds, whereas these things are used to record values with > smaller granulatiry, are stored in jiffies, and that's why we get zero > on read and writes have crazy effects. Oops. Assume me with brown paper bag etc.etc. It was a typo for proc_dointvec_ms_jiffies > > Also, as Andi stated, this is not the way to deal with this problem. > > So we have a broken patch, which even if implemented properly isn't the > way forward, so I consider this discussion dead in the water until we > have some test cases. The patch is easy to fix with a s/_jiffies/_ms_jiffies/g Also it was more intended for him to play around and get some data points. I guess for that it's still useful. Also while for that it's probably not the right solution, but I could imagine in some other situations where it might be useful to tune these values. After all they are not written down in stone. I wonder if it would even make sense to consider hr timers for TCP now. =Andi -- ak@linux.intel.com