From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757267Ab2FTRih (ORCPT ); Wed, 20 Jun 2012 13:38:37 -0400 Received: from casper.infradead.org ([85.118.1.10]:35781 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756986Ab2FTRig convert rfc822-to-8bit (ORCPT ); Wed, 20 Jun 2012 13:38:36 -0400 Message-ID: <1340213901.21745.122.camel@twins> Subject: Re: [PATCH v3] sched: balance_cpu to consider other cpus in its group as target of (pinned) task From: Peter Zijlstra To: Prashanth Nageshappa Cc: mingo@kernel.org, LKML , roland@kernel.org, Srivatsa Vaddagiri , efault@gmx.de, Ingo Molnar Date: Wed, 20 Jun 2012 19:38:21 +0200 In-Reply-To: <4FE06CDB.2060605@linux.vnet.ibm.com> References: <4FE06CDB.2060605@linux.vnet.ibm.com> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2012-06-19 at 17:43 +0530, Prashanth Nageshappa wrote: > T2 will starve eternally in this case. The same > scenario can arise in presence of non-rt tasks as well (say we replace F1 with > high irq load or with a very high priority SCHED_OTHER task that can't move out > of C2). Uhm, no. In the case where both F1 and T2 are SCHED_OTHER starvation is impossible. What can happen with pure SCHED_OTHER affinities is being less fair than desired. Anyway, I took the patch with a few minor edits -- ie. we don't need to reset loop_break, its never changed (same for the ALL_PINNED patch you sent).