From mboxrd@z Thu Jan 1 00:00:00 1970 From: Asim Shankar Subject: SFQ: Reordering? Date: Fri, 6 May 2005 16:53:51 -0500 Message-ID: <7bca1cb5050506145344d16b1e@mail.gmail.com> Reply-To: Asim Shankar Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Return-path: To: netdev@oss.sgi.com Content-Disposition: inline Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org Hi, I was looking through sch_sfq.c. From what I could make out, if the perturbation period is non-zero (say Xseconds), then ever X seconds, sfq_perturbation() is invoked. This changes the perturbation value that will be used by the hash function, however, packets already existing in the queue aren't rehashed. As a result, new packets being enqueued will have a different hash value and thus packet re-ordering will take place. I ran a quick test using netperf and tcpdump and seem to notice this re-ordering. Should complete rehashing take place in sfq_perturbation(), or am I missing something? (I was looking at 2.6.9 and also took a cursory glance at 2.6.11 on lxr.linux.no) Thanks, -- Asim