Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 3 Feb 2002 17:34:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 3 Feb 2002 17:34:44 -0500 Received: from mx2.elte.hu ([157.181.151.9]:3718 "HELO mx2.elte.hu") by vger.kernel.org with SMTP id ; Sun, 3 Feb 2002 17:34:36 -0500 Date: Mon, 4 Feb 2002 01:32:14 +0100 (CET) From: Ingo Molnar Reply-To: To: Steffen Persvold Cc: Jens Axboe , lkml Subject: Re: Short question regarding generic_make_request() In-Reply-To: <3C5DB965.643661F2@scali.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 3 Feb 2002, Steffen Persvold wrote: > Ok, the reason I'm asking is that I receive a request from a remote > machine on interrupt level (tasklet) and want to submit this to the > local device. The reason I'm using a tasklet instead of a kernel > thread is that somewhere between RedHat's 2.4.3-12 and 2.4.9-12 > kernels the latency of waking up a kernel thread increased (using a > semaphore method similar to the one used in loop.c). I don't know why > this happened, but I guess that if I still could use a kernel thread > there wouldn't be any problems using generic_make_request(). you really want a kernel thread for this. The wakeup latency of a kernel thread is on the order of 2-3 usecs (context switch overhead included), nothing compared to usual block IO costs. you say that the latency of waking up a kernel thread has increased - by how much? Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/