From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758110AbbEaBjr (ORCPT ); Sat, 30 May 2015 21:39:47 -0400 Received: from e23smtp09.au.ibm.com ([202.81.31.142]:57354 "EHLO e23smtp09.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754741AbbEaBji (ORCPT ); Sat, 30 May 2015 21:39:38 -0400 Message-ID: <1433036302.4526.15.camel@au1.ibm.com> Subject: Re: [PATCH] cpuidle: powernv/pseries: Decrease the snooze residency From: Benjamin Herrenschmidt To: svaidy@linux.vnet.ibm.com Cc: Preeti U Murthy , linux-pm@vger.kernel.org, Daniel Lezcano , rjw@rjwysocki.net, linux-kernel@vger.kernel.org, anton@samba.org, Shilpasri G Bhat , linuxppc-dev@lists.ozlabs.org Date: Sat, 30 May 2015 20:38:22 -0500 In-Reply-To: <20150530060141.GA19134@dirshya.in.ibm.com> References: <1432902728-31476-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com> <55686DE5.6010001@linux.vnet.ibm.com> <20150530060141.GA19134@dirshya.in.ibm.com> Organization: IBM Australia Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.11-0ubuntu3 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15053101-0033-0000-0000-00000195CF50 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2015-05-30 at 11:31 +0530, Vaidyanathan Srinivasan wrote: > In shared lpar case, spinning in guest context may potentially take > away cycles from other lpars waiting to run on the same physical cpu. > > So the policy in shared lpar case is to let PowerVM hypervisor know > immediately that the guest cpu is idle which will allow the hypervisor > to use the cycles for other tasks/lpars. But that will have negative side effects under KVM no ? Suresh mentioned something with his new directed interrupts code that we had many cases where the interrupts ended up arriving shortly after we exited to host for NAP'ing ... Snooze might fix it... Ben.