From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754135AbZFWRqS (ORCPT ); Tue, 23 Jun 2009 13:46:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751936AbZFWRqM (ORCPT ); Tue, 23 Jun 2009 13:46:12 -0400 Received: from mx2.redhat.com ([66.187.237.31]:53900 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750800AbZFWRqL (ORCPT ); Tue, 23 Jun 2009 13:46:11 -0400 Date: Tue, 23 Jun 2009 16:30:54 +0200 From: Oleg Nesterov To: Ratan Nalumasu Cc: Andrew Morton , Ingo Molnar , Roland McGrath , Vitaly Mayatskikh , linux-kernel@vger.kernel.org Subject: Re: [RFC,PATCH 0/2] do_wait() wakeup optimization Message-ID: <20090623143054.GA10069@redhat.com> References: <20090622170432.GA4895@redhat.com> <93ad5f3f0906230955x357ff9evc334d4a5c6def20@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <93ad5f3f0906230955x357ff9evc334d4a5c6def20@mail.gmail.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/23, Ratan Nalumasu wrote: > > Yes, it is something we really need. The specific case I have (hundreds of > NTPL threads in a program, and each thread managing a child process), the > CPU load is >99% with NTPL threads, near 0% with the patch ^^^^^^^^^ Thanks. Did you test this patch, or do you mean the previous one? > So, yes, the complication is worthwhile. I am asking because I am not sure this change is enough, note the "We can make child_wait_callback() more clever later" in the changelog. __wake_up_parent() passes key = p, but we can pass more info and do additional checks in child_wait_callback(). Oleg.