Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261410AbVBQPAv (ORCPT ); Thu, 17 Feb 2005 10:00:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262244AbVBQO6z (ORCPT ); Thu, 17 Feb 2005 09:58:55 -0500 Received: from cpe-24-94-57-164.stny.res.rr.com ([24.94.57.164]:27327 "EHLO localhost.localdomain") by vger.kernel.org with ESMTP id S261410AbVBQO5i (ORCPT ); Thu, 17 Feb 2005 09:57:38 -0500 Date: Thu, 17 Feb 2005 09:57:33 -0500 (EST) From: Steven Rostedt X-X-Sender: rostedt@localhost.localdomain Reply-To: rostedt@kihontech.com To: Ingo Molnar cc: "David S. Miller" , mgross@linux.intel.com, linux-kernel@vger.kernel.org, Mark_H_Johnson@raytheon.com Subject: Re: queue_work from interrupt Real time preemption2.6.11-rc2-RT-V0.7.37-03 In-Reply-To: <20050217075212.GA21621@elte.hu> Message-ID: References: <200502141240.14355.mgross@linux.intel.com> <200502141429.11587.mgross@linux.intel.com> <20050215104153.GB19866@elte.hu> <200502151006.44809.mgross@linux.intel.com> <20050216051645.GB15197@elte.hu> <20050216081143.50d0a9d6.davem@davemloft.net> <20050217075212.GA21621@elte.hu> 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 Content-Length: 1565 Lines: 38 On Thu, 17 Feb 2005, Ingo Molnar wrote: > as long as it stays on a single CPU, could we allow softirq contexts to > preempt each other? I.e. we'd keep the per-CPU assumption (that is fair > and needed for performance anyway), but we'd allow NET_TX to preempt > NET_RX and vice versa. Would this corrupt the rx/tx queues? (i suspect > it would.) > > (anyway, by adding an explicit no-preempt section around the 'take > current rx queue private, then process it' on PREEMPT_RT it could be > made safe. I'm wondering whether there are any other deeper assumptions > about atomic separation of softirq contexts.) > Ingo, Wouldn't this cause a longer latency in these sections. I understand that turning preemption off doesn't stop interrupts that are not threaded, but especially on a UP, this would cause higher latencies for high priority processes when a lower priority process is heavy on network traffic. As I mentioned earlier, what would it take to be able to group softirq threads that should not preempt each other, but still keep preemption available for other threads? Actually, I guess I need to ask, what do you intend on doing to prioritize the softirq? Are you going to make a separate thread for each tasklet? Once I see what you're doing, I'll make something up to help handle this problem. -- Steve - 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/