Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262650AbVDANlq (ORCPT ); Fri, 1 Apr 2005 08:41:46 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262736AbVDANlq (ORCPT ); Fri, 1 Apr 2005 08:41:46 -0500 Received: from mx2.elte.hu ([157.181.151.9]:44756 "EHLO mx2.elte.hu") by vger.kernel.org with ESMTP id S262650AbVDANlo (ORCPT ); Fri, 1 Apr 2005 08:41:44 -0500 Date: Fri, 1 Apr 2005 15:41:27 +0200 From: Ingo Molnar To: kus Kusche Klaus Cc: stern@rowland.harvard.edu, linux-usb-users@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: 2.6.11, USB: High latency? Message-ID: <20050401134127.GA4992@elte.hu> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i X-ELTE-SpamVersion: MailScanner 4.31.6-itk1 (ELTE 1.2) SpamAssassin 2.63 ClamAV 0.73 X-ELTE-VirusStatus: clean X-ELTE-SpamCheck: no X-ELTE-SpamCheck-Details: score=-4.9, required 5.9, autolearn=not spam, BAYES_00 -4.90 X-ELTE-SpamLevel: X-ELTE-SpamScore: -4 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1220 Lines: 29 * kus Kusche Klaus wrote: > IRQ 7-724 0d..1 1us : end_8259A_irq (do_hardirq) > IRQ 7-724 0d..1 1us!: enable_8259A_irq (do_hardirq) > IRQ 7-724 0d... 832us : do_hardirq (do_irqd) > IRQ 7-724 0d... 833us : trace_irqs_on (do_hardirq) > mmap-1000 0d.h1 21us : end_8259A_irq (__do_IRQ) > mmap-1000 0d.h1 22us!: enable_8259A_irq (__do_IRQ) > mmap-1000 0d.h. 662us : irq_exit (do_IRQ) > mmap-1000 0d..1 662us : do_softirq (irq_exit) > mmap-1000 0d.h. 0us : do_IRQ (c012d6d5 7 0) > mmap-1000 0d.h1 2us!: mask_and_ack_8259A (__do_IRQ) > mmap-1000 0d.h1 938us : redirect_hardirq (__do_IRQ) > mmap-1000 0d.h1 939us : wake_up_process (redirect_hardirq) such 'freezes' almost certainly signal some sort of hardware latency - some device holding the system bus up during DMA. There is no algorithmic reason for any of those steps above to take several hundreds of microseconds. 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/