Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759937AbYB1Puq (ORCPT ); Thu, 28 Feb 2008 10:50:46 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761313AbYB1Pu2 (ORCPT ); Thu, 28 Feb 2008 10:50:28 -0500 Received: from viefep31-int.chello.at ([62.179.121.49]:62176 "EHLO viefep31-int.chello.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761288AbYB1Pu0 (ORCPT ); Thu, 28 Feb 2008 10:50:26 -0500 Subject: Re: [PATCH] proc: Add RLIMIT_RTTIME to /proc//limits From: Peter Zijlstra To: Michael Kerrisk Cc: Michael Kerrisk , Eugene Teo , linux-kernel@vger.kernel.org, Neil Horman , Ingo Molnar In-Reply-To: References: <20080208145950.GA3910@kernel.sg> <1202483445.6292.1.camel@lappy> <517f3f820802280712o3d756b4fq46461b226515e1f2@mail.gmail.com> <1204212100.12120.9.camel@twins> Content-Type: text/plain Date: Thu, 28 Feb 2008 16:50:21 +0100 Message-Id: <1204213821.12120.15.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.21.90 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1561 Lines: 42 On Thu, 2008-02-28 at 16:44 +0100, Michael Kerrisk wrote: > Peter, > > Thanks for the text. > > On Thu, Feb 28, 2008 at 4:21 PM, Peter Zijlstra wrote: > > > > On Thu, 2008-02-28 at 16:12 +0100, Michael Kerrisk wrote: > > > Peter, > > > > > > Could you please provide some text describing RLIMIT_RTTIMEfor the > > > getrlimit.2 man page. > > > > The rlimit sets a timeout in [us] for SCHED_RR and SCHED_FIFO tasks. > > This time is measured between sleeps, so a schedule in RR or a > > preemption in either is not a sleep - the task needs to be dequeued and > > enqueued for the timer to reset. > > Just to clarify: sleep here means a call to some blocking syscall > (e.g., nanosleep(), read(), select(), etc.), right? Is there anything > else that falls under the category of "sleep"? What about a call to > sched_yield() where the process explicitly lets go of the CPU? Yes, and yes, others would be blocking on futexes and the like. > Also, is this limit per-thread or per-process? I assume the latter -- > but can you confirm please. Per process. Requests have been made to allow for per thread, but rlimits are not. Its really not meant as a fine-grained deadline notification mechanism, we have posix timers for that, but as a watchdog to ensure we behave 'well'. -- 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/