From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753437Ab1LUKi2 (ORCPT ); Wed, 21 Dec 2011 05:38:28 -0500 Received: from e28smtp06.in.ibm.com ([122.248.162.6]:59843 "EHLO e28smtp06.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752429Ab1LUKiZ (ORCPT ); Wed, 21 Dec 2011 05:38:25 -0500 From: Nikunj A Dadhania To: Ingo Molnar , Avi Kivity Cc: 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: <20111219112326.GA15090@elte.hu> References: <20111219083141.32311.9429.stgit@abhimanyu.in.ibm.com> <20111219112326.GA15090@elte.hu> User-Agent: Notmuch/0.10.2+70~gf0e0053 (http://notmuchmail.org) Emacs/23.3.1 (x86_64-redhat-linux-gnu) Date: Wed, 21 Dec 2011 16:09:36 +0530 Message-ID: <87sjke1a53.fsf@abhimanyu.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii x-cbid: 11122110-9574-0000-0000-0000009C9287 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 19 Dec 2011 12:23:26 +0100, Ingo Molnar wrote: > > * Nikunj A. Dadhania wrote: > > So could we please approach this from the benchmarked workload > angle first? The highest improvement is in ebizzy: > > > ebizzy 2vm (improved 15 times, i.e. 1520%) > > 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? > This is from the perf run on the host: Baseline: 16.22% qemu-kvm [kvm_intel] [k] free_kvm_area 8.27% qemu-kvm [kvm] [k] start_apic_timer 7.53% qemu-kvm [kvm] [k] kvm_put_guest_fpu Gang: 24.44% qemu-kvm [kvm_intel] [k] free_kvm_area 13.42% qemu-kvm [kvm] [k] start_apic_timer 9.91% qemu-kvm [kvm] [k] kvm_put_guest_fpu Ingo, Avi, I am not getting anything obvious from this. Any ideas? Regards Nikunj