From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752846Ab1LSMFp (ORCPT ); Mon, 19 Dec 2011 07:05:45 -0500 Received: from e23smtp09.au.ibm.com ([202.81.31.142]:37572 "EHLO e23smtp09.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752295Ab1LSMFn (ORCPT ); Mon, 19 Dec 2011 07:05:43 -0500 From: Nikunj A Dadhania To: Avi Kivity Cc: Ingo Molnar , peterz@infradead.org, linux-kernel@vger.kernel.org, vatsa@linux.vnet.ibm.com, bharata@linux.vnet.ibm.com Subject: Re: [RFC PATCH 0/4] Gang scheduling in CFS In-Reply-To: <4EEF2729.6080501@redhat.com> References: <20111219083141.32311.9429.stgit@abhimanyu.in.ibm.com> <20111219112326.GA15090@elte.hu> <4EEF2382.4010605@redhat.com> <87hb0wbx0p.fsf@abhimanyu.in.ibm.com> <4EEF2729.6080501@redhat.com> User-Agent: Notmuch/0.10.2+70~gf0e0053 (http://notmuchmail.org) Emacs/23.3.1 (x86_64-redhat-linux-gnu) Date: Mon, 19 Dec 2011 17:36:52 +0530 Message-ID: <87ehw0bw9v.fsf@abhimanyu.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii x-cbid: 11121902-3568-0000-0000-000000E8C8A2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 19 Dec 2011 13:59:37 +0200, Avi Kivity wrote: > On 12/19/2011 01:50 PM, Nikunj A Dadhania wrote: > > On Mon, 19 Dec 2011 13:44:02 +0200, Avi Kivity wrote: > > > On 12/19/2011 01:23 PM, Ingo Molnar wrote: > > > > What's behind this huge speedup? Does ebizzy use user-space > > > > spinlocks perhaps? Could we do something on the user-space side > > > > to get a similar speedup? > > > > > > kvm tries to detect spinlocks (by trapping repeated executions of PAUSE) > > > and yield to a related vcpu. It's far from perfect however, and relies > > > on the spinlock code using PAUSE. > > > > > Avi, is this soft-PLE kind of thing? > > No, hard PLE, see the calls to yield_to. > The above ebizzy result is from a non-PLE machine, will yield_to come in to picture here? I have two set of results, one for PLE machine and other for non-PLE. Nikunj