Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751670AbdFHT7L (ORCPT ); Thu, 8 Jun 2017 15:59:11 -0400 Received: from merlin.infradead.org ([205.233.59.134]:51514 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750788AbdFHT7K (ORCPT ); Thu, 8 Jun 2017 15:59:10 -0400 Date: Thu, 8 Jun 2017 21:59:00 +0200 From: Peter Zijlstra To: Subhra Mazumdar Cc: linux-kernel@vger.kernel.org, mingo@kernel.org Subject: Re: [RFC PATCH] sched: select_idle_core should select least utilized core Message-ID: <20170608195900.GA8337@worktop.programming.kicks-ass.net> References: <1496949992-629076-1-git-send-email-subhra.mazumdar@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1496949992-629076-1-git-send-email-subhra.mazumdar@oracle.com> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 501 Lines: 9 On Thu, Jun 08, 2017 at 03:26:32PM -0400, Subhra Mazumdar wrote: > Current select_idle_core tries to find a fully idle core and if it fails > select_idle_cpu next returns any idle cpu in the llc domain. This is not optimal > for architectures with many (more than 2) hyperthreads in a core. This patch > changes select_idle_core to find the core with least number of busy > hyperthreads and return an idle cpu in that core. Yeah, I think not. That makes select_idle_siblings _vastly_ more expensive.