Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751326Ab3JUQGo (ORCPT ); Mon, 21 Oct 2013 12:06:44 -0400 Received: from e7.ny.us.ibm.com ([32.97.182.137]:58651 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750937Ab3JUQGn (ORCPT ); Mon, 21 Oct 2013 12:06:43 -0400 From: Raghavendra K T To: , , , , , Cc: , , , , Raghavendra K T Subject: [PATCH] x86 kconfig: Add recommendation to enable paravirt spinlock Date: Mon, 21 Oct 2013 21:35:08 +0530 Message-Id: <1382371508-3843-1-git-send-email-raghavendra.kt@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.11.7 In-Reply-To: References: X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13102116-5806-0000-0000-00002327CA77 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1570 Lines: 41 Since paravirt spinlock optimization are in 3.12 kernel, we have very good performance benefit for paravirtualized KVM / Xen kernel. Also we no longer suffer from 5% side effect on native kernel. Signed-off-by: Raghavendra K T --- Would like to thank Sander for spotting and suggesting this. pvspinlock benefit on KVM link: https://lkml.org/lkml/2013/8/6/178 Attilio's tests on native kernel impact: http://blog.xen.org/index.php/2012/05/11/benchmarking-the-new-pv-ticketlock-implementation/ arch/x86/Kconfig | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index f67e839..4ba9d32 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -638,10 +638,10 @@ config PARAVIRT_SPINLOCKS spinlock implementation with something virtualization-friendly (for example, block the virtual CPU rather than spinning). - Unfortunately the downside is an up to 5% performance hit on - native kernels, with various workloads. + It has minimal impact on native kernels and gives nice performance + benefit for paravirtualized KVM / Xen kernels. - If you are unsure how to answer this question, answer N. + If you are unsure how to answer this question, answer Y. source "arch/x86/xen/Kconfig" -- 1.7.11.7 -- 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/