From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Thu, 14 Aug 2003 17:45:22 +0100 (BST) Received: from gateway-1237.mvista.com ([IPv6:::ffff:12.44.186.158]:27126 "EHLO orion.mvista.com") by linux-mips.org with ESMTP id ; Thu, 14 Aug 2003 17:45:19 +0100 Received: (from jsun@localhost) by orion.mvista.com (8.11.6/8.11.6) id h7EGjF601287; Thu, 14 Aug 2003 09:45:15 -0700 Date: Thu, 14 Aug 2003 09:45:15 -0700 From: Jun Sun To: "Sirotkin, Alexander" Cc: linux-mips@linux-mips.org, jsun@mvista.com Subject: Re: tasklet latency and system calls on mips Message-ID: <20030814094515.B1203@mvista.com> References: <3F3A411C.70603@ti.com> <20030813095446.C9655@mvista.com> <3F3B53C0.30408@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <3F3B53C0.30408@ti.com>; from demiurg@ti.com on Thu, Aug 14, 2003 at 12:17:52PM +0300 Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 3052 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: jsun@mvista.com Precedence: bulk X-list: linux-mips On Thu, Aug 14, 2003 at 12:17:52PM +0300, Sirotkin, Alexander wrote: > > I suspect that what happens is as follows : > > system call arrives and while it's being processed and interrupt to one > of the drivers arrives. This interrupt > schedules a tasklet which however is not executed after the system call > finishes, The tasklet should be executed at the return of interrupt handling. If not, there is a bug. > only after the next timer > interrupt which causes up to 10 ms latency (not all the time, only when > somebody makes a system call). > BTW, make sure tasklet_schedule() is indeed called in an interrupt handler. I am not sure why will happen otherwise. If you suspect it is a bug, you can easily trace them. You may my little tracing tool useful, http://linux.junsun.net/patches/generic/experimental/030716.a-jstrace.patch Jun