From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932078AbXACUU1 (ORCPT ); Wed, 3 Jan 2007 15:20:27 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932080AbXACUU0 (ORCPT ); Wed, 3 Jan 2007 15:20:26 -0500 Received: from rrcs-24-153-217-226.sw.biz.rr.com ([24.153.217.226]:37338 "EHLO smtp.opengridcomputing.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932078AbXACUUS (ORCPT ); Wed, 3 Jan 2007 15:20:18 -0500 Subject: Re: [PATCH v4 01/13] Linux RDMA Core Changes From: Steve Wise To: "Michael S. Tsirkin" Cc: netdev@vger.kernel.org, Roland Dreier , linux-kernel@vger.kernel.org, openib-general@openib.org In-Reply-To: <20070103193324.GD29003@mellanox.co.il> References: <1167851839.4187.36.camel@stevo-desktop> <20070103193324.GD29003@mellanox.co.il> Content-Type: text/plain Date: Wed, 03 Jan 2007 14:20:18 -0600 Message-Id: <1167855618.4187.65.camel@stevo-desktop> Mime-Version: 1.0 X-Mailer: Evolution 2.4.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2007-01-03 at 21:33 +0200, Michael S. Tsirkin wrote: > > Without extra param (1000 iterations in cycles): > > ave 101.283 min 91 max 247 > > With extra param (1000 iterations in cycles): > > ave 103.311 min 91 max 221 > > A 2% hit then. Not huge, but 0 either. > > > Convert cycles to ns (3466.727 MHz CPU): > > > > Without: 101.283 / 3466.727 = .02922us == 29.22ns > > With: 103.311 / 3466.727 = .02980us == 29.80ns > > > > So I measure a .58ns average increase for passing in the additional > > parameter. > > That depends on CPU speed though. Percentage is likely to be more universal. > > > Here is a snipit of the test: > > > > spin_lock_irq(&lock); > > do_gettimeofday(&start_tv); > > for (i=0; i<1000; i++) { > > cycles_start[i] = get_cycles(); > > ib_req_notify_cq(cb->cq, IB_CQ_NEXT_COMP); > > cycles_stop[i] = get_cycles(); > > } > > do_gettimeofday(&stop_tv); > > spin_unlock_irq(&lock); > > > > if (stop_tv.tv_usec < start_tv.tv_usec) { > > stop_tv.tv_usec += 1000000; > > stop_tv.tv_sec -= 1; > > } > > > > for (i=0; i < 1000; i++) { > > cycles_t v = cycles_stop[i] - cycles_start[i]; > > sum += v; > > if (v > max) > > max = v; > > if (min == 0 || v < min) > > min = v; > > } > > > > printk(KERN_ERR PFX "FOO delta sec %lu usec %lu sum %llu min %llu max %llu\n", > > stop_tv.tv_sec - start_tv.tv_sec, > > stop_tv.tv_usec - start_tv.tv_usec, > > (unsigned long long)sum, (unsigned long long)min, > > (unsigned long long)max); > > Good job, the test looks good, thanks. > > So what does this tell you? > To me it looks like there's a measurable speed difference, > and so we should find a way (e.g. what I proposed) to enable chelsio userspace > without adding overhead to other low level drivers or indeed chelsio kernel level code. > > What do you think? Roland? > I think having a 2nd function to set the udata seems onerous.