From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 3 Feb 2002 17:28:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 3 Feb 2002 17:28:37 -0500 Received: from elin.scali.no ([62.70.89.10]:34319 "EHLO elin.scali.no") by vger.kernel.org with ESMTP id ; Sun, 3 Feb 2002 17:28:15 -0500 Message-ID: <3C5DB965.643661F2@scali.com> Date: Sun, 03 Feb 2002 23:27:49 +0100 From: Steffen Persvold X-Mailer: Mozilla 4.76 [en] (X11; U; Linux 2.4.9-ac18 i686) X-Accept-Language: en MIME-Version: 1.0 To: Jens Axboe CC: Ingo Molnar , lkml Subject: Re: Short question regarding generic_make_request() In-Reply-To: <3C5D3BC9.CA9E24A@scali.com> <20020203143946.H29553@suse.de> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Jens Axboe wrote: > > On Sun, Feb 03 2002, Ingo Molnar wrote: > > > > On Sun, 3 Feb 2002, Steffen Persvold wrote: > > > > > Can generic_make_request() be called from interrupt level (or tasklet) > > > ? > > > > no. > > In theory, READA from interrupt context would be ok, though. That > doesn't work in real-life due to the non flag saving spin locking in > __make_request. > 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(). Regards, -- Steffen Persvold | Scalable Linux Systems | Try out the world's best mailto:sp@scali.com | http://www.scali.com | performing MPI implementation: Tel: (+47) 2262 8950 | Olaf Helsets vei 6 | - ScaMPI 1.13.8 - Fax: (+47) 2262 8951 | N0621 Oslo, NORWAY | >320MBytes/s and <4uS latency