Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759748Ab3JOVyO (ORCPT ); Tue, 15 Oct 2013 17:54:14 -0400 Received: from vserver.eikelenboom.it ([84.200.39.61]:57788 "EHLO smtp.eikelenboom.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759560Ab3JOVyN (ORCPT ); Tue, 15 Oct 2013 17:54:13 -0400 X-Greylist: delayed 489 seconds by postgrey-1.27 at vger.kernel.org; Tue, 15 Oct 2013 17:54:13 EDT Date: Tue, 15 Oct 2013 23:45:58 +0200 From: Sander Eikelenboom Organization: Eikelenboom IT services X-Priority: 3 (Normal) Message-ID: <932951750.20131015234558@eikelenboom.it> To: Raghavendra K T CC: linux-kernel@vger.kernel.org Subject: Kconfig help entry for CONFIG_PARAVIRT_SPINLOCK MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1532 Lines: 43 Hi Raghavendra, Since the ticketlock series have landed in this mergewindow (thanks :-) ) the help accompanying the Kconfig entry doesn't seem to reflect the current state well. - Wasn't the whole purpose of the ticketlock series to mitigate this 5% performance hit to something far less, so distro kernels could enable this for their normal kernels ? I don't have the exact performance figures though. - Perhaps the suggestion to enable this for supported hypervisors (Xen and KVM ?) could be added ? -- Sander CONFIG_PARAVIRT_SPINLOCKS: Paravirtualized spinlocks allow a pvops backend to replace the 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. If you are unsure how to answer this question, answer N. Symbol: PARAVIRT_SPINLOCKS [=y] Type : boolean Prompt: Paravirtualization layer for spinlocks Location: -> Processor type and features -> Linux guest support (HYPERVISOR_GUEST [=y]) -> Enable paravirtualization code (PARAVIRT [=y]) Defined at arch/x86/Kconfig:632 Depends on: HYPERVISOR_GUEST [=y] && PARAVIRT [=y] && SMP [=y] Selects: UNINLINE_SPIN_UNLOCK [=y] -- 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/