From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Revell Subject: RE: My vote against eepro* removal Date: Fri, 20 Jan 2006 19:45:45 -0500 Message-ID: <1137804346.3241.38.camel@mindpipe> References: Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Evgeniy Polyakov , John Ronciak , Adrian Bunk , linux-kernel@vger.kernel.org, john.ronciak@intel.com, ganesh.venkatesan@intel.com, jesse.brandeburg@intel.com, netdev@vger.kernel.org, Steven Rostedt Return-path: To: kus Kusche Klaus In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Fri, 2006-01-20 at 11:19 +0100, kus Kusche Klaus wrote: > For a non-full preemption kernel, your patch moves the 500 us > piece of code from kernel to thread context, so it really > improves things. But is 500 us something to worry about in a > non-full preemption kernel? Yes, absolutely. Once exit_mmap (a latency regression which was introduced in 2.6.14) and rt_run_flush/rt_garbage_collect (which have always been problematic) are fixed, 500usecs will stick out like a sore thumb even on a regular PREEMPT kernel. Also, you should be able to capture this latency in /proc/latency trace by configuring an -rt kernel with PREEMPT_DESKTOP and hard/softirq preemption disabled. Lee