Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268650AbUILKrb (ORCPT ); Sun, 12 Sep 2004 06:47:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268658AbUILKra (ORCPT ); Sun, 12 Sep 2004 06:47:30 -0400 Received: from ozlabs.org ([203.10.76.45]:9612 "EHLO ozlabs.org") by vger.kernel.org with ESMTP id S268652AbUILKqo (ORCPT ); Sun, 12 Sep 2004 06:46:44 -0400 Date: Sun, 12 Sep 2004 20:43:06 +1000 From: Anton Blanchard To: Arnd Bergmann Cc: Zwane Mwaikambo , Linus Torvalds , Paul Mackerras , Linux Kernel , Andrew Morton , "Nakajima, Jun" , Andi Kleen , Ingo Molnar , Martin Schwidefsky Subject: Re: [PATCH] Yielding processor resources during lock contention Message-ID: <20040912104306.GA25741@krispykreme> References: <200409121210.32259.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200409121210.32259.arnd@arndb.de> User-Agent: Mutt/1.5.6+20040818i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 861 Lines: 23 Hi, > For s390, this was solved by simply defining cpu_relax() to the hypervisor > yield operation, because we found that cpu_relax() is used only in busy-wait > situations where it makes sense to continue on another virtual CPU. > > What is the benefit of not always doing a full hypervisor yield when > you hit cpu_relax()? cpu_relax doesnt tell us why we are busy looping. In this particular case we want to pass to the hypervisor which virtual cpu we are waiting on so the hypervisor make better scheduling decisions. Did you manage to see any improvement by yielding to the hypervisor in cpu_relax? Anton - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/