From owner-freebsd-performance@FreeBSD.ORG Tue Jun 13 20:02:00 2006 Return-Path: X-Original-To: freebsd-performance@freebsd.org Delivered-To: freebsd-performance@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 4236516A41A; Tue, 13 Jun 2006 20:02:00 +0000 (UTC) (envelope-from scottl@samsco.org) Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57]) by mx1.FreeBSD.org (Postfix) with ESMTP id 9637A43D46; Tue, 13 Jun 2006 20:01:59 +0000 (GMT) (envelope-from scottl@samsco.org) Received: from [10.10.3.185] ([69.15.205.254]) (authenticated bits=0) by pooker.samsco.org (8.13.4/8.13.4) with ESMTP id k5DK1kTT068725; Tue, 13 Jun 2006 14:01:53 -0600 (MDT) (envelope-from scottl@samsco.org) Message-ID: <448F19A4.8040901@samsco.org> Date: Tue, 13 Jun 2006 14:01:40 -0600 From: Scott Long User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.7.12) Gecko/20060206 X-Accept-Language: en-us, en MIME-Version: 1.0 To: danial_thom@yahoo.com References: <20060613195738.64419.qmail@web33310.mail.mud.yahoo.com> In-Reply-To: <20060613195738.64419.qmail@web33310.mail.mud.yahoo.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=0.0 required=3.8 tests=none autolearn=failed version=3.1.1 X-Spam-Checker-Version: SpamAssassin 3.1.1 (2006-03-10) on pooker.samsco.org Cc: freebsd-performance@freebsd.org, Robert Watson , David Xu Subject: Re: Initial 6.1 questions X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 13 Jun 2006 20:02:00 -0000 Danial Thom wrote: > > --- Scott Long wrote: > > >>Danial Thom wrote: >> >>>--- Robert Watson >> >>wrote: >> >>> >>>>On Tue, 13 Jun 2006, Danial Thom wrote: >>>> >>>> >>>> >>>>>Maybe someone can explain this output. The >>>> >>>>top line shows 99.6%idle. Is it >>>> >>>> >>>>>just showing CPU 0s stats on the top line? >>>> >>>>Two types of measurements are taken: sampled >>>>ticks regarding whether the >>>>system as a while is in {user, nice, system, >>>>intr, idle}, and then sampling >>>>for individual processes. Right now, the >>>>system measurements are kept in a >>>>simple array of tick counters called cp_time. >> >>>>John Baldwin and others have >>>>changes that make these tick counters >> >>per-CPU. >> >>>>The lines at the top of >>>>top(1)'s output are derived from those tick >>>>counters. Ticks are measured on >>>>each CPU, so those are a summary across all >>>>CPUs. To add cpustat support, we >>>>need to merge John's patch to make cp_time >>>>per-CPU (ie., different counters >>>>for different CPUs) and teach the userland >>>>tools to retrieve them. When you >>>>run top you'll notice that it adjusts the >>>>measurements each refresh. In >>>>effect, what it's doing is sampling the >> >>change >> >>>>in tick counts over the window, >>>>pulling down the new values and calculating >> >>the >> >>>>percentages of ticks in each >>>>"bucket" in the last window. >>> >>> >>>That doesn't explain why the Top line shows >> >>99.6% >> >>>idle, but the cpu idle threads are showing >>>significant usage. >>> >>>I'm getting a constant 6000 Interrupts / >> >>Second >> >>>on my em controller, yet top jumps all over >> >>the >> >>>place; sitting at 99% idle for 10 seconds, >> >>then >> >>>jumping to 50%, then somewhere in between. It >>>seems completely unreliable. The load I'm >>>applying is constant. >>> >>>DT >> >>Be aware that there was a significant change >>made to if_em >>in 7-CURRENT in Jan 2006 to improve load >>performance. It'll >>probably get backported for 6.2, but you might >>consider >>looking at it before you make up your mind on >>6.1 performance. > > > I can bridge 1 million pps with the em driver in > 4.9, and it looks pretty much intact in 6.1, so > I'm not too worried about the em driver being the > problem here. Plus the measurements look just > fine with 1 cpu, and they are completely > impossible in SMP mode. So its reasonable to > conclude that the measurement tools simply don't > work. > > Since everyone agrees that the load measuring > tools aren't all that accurate, what criteria was > used to determine that the changes made in 7 have > the effect that you think they have had? > > DT > DT > It was tested with a Smartbits packet generator. The tx rate on the generator was increased in steps until the host started dropping packets or became otherwise unresponsive. Scott