Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751304AbaACKOQ (ORCPT ); Fri, 3 Jan 2014 05:14:16 -0500 Received: from smtp.citrix.com ([66.165.176.89]:12262 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750922AbaACKOP (ORCPT ); Fri, 3 Jan 2014 05:14:15 -0500 X-IronPort-AV: E=Sophos;i="4.95,597,1384300800"; d="scan'208";a="89487629" Message-ID: <52C68D73.70005@citrix.com> Date: Fri, 3 Jan 2014 10:14:11 +0000 From: David Vrabel User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.16) Gecko/20121215 Iceowl/1.0b1 Icedove/3.0.11 MIME-Version: 1.0 To: Mukesh Rathor CC: Konrad Rzeszutek Wilk , , , , Subject: Re: [PATCH v12 06/18] xen/pvh: MMU changes for PVH (v2) References: <1388550945-25499-1-git-send-email-konrad.wilk@oracle.com> <1388550945-25499-7-git-send-email-konrad.wilk@oracle.com> <52C54C82.5010802@citrix.com> <20140102173639.3869d841@mantra.us.oracle.com> In-Reply-To: <20140102173639.3869d841@mantra.us.oracle.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.2.76] X-DLP: MIA2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1280 Lines: 34 On 03/01/14 01:36, Mukesh Rathor wrote: > On Thu, 2 Jan 2014 11:24:50 +0000 > David Vrabel wrote: > >> On 01/01/14 04:35, Konrad Rzeszutek Wilk wrote: >>> From: Mukesh Rathor >>> >>> .. which are surprinsingly small compared to the amount for PV code. >>> >>> PVH uses mostly native mmu ops, we leave the generic (native_*) for >>> the majority and just overwrite the baremetal with the ones we need. >>> >>> We also optimize one - the TLB flush. The native operation would >>> needlessly IPI offline VCPUs causing extra wakeups. Using the >>> Xen one avoids that and lets the hypervisor determine which >>> VCPU needs the TLB flush. >> >> This TLB flush optimization should be a separate patch. > > It's not really an "optimization", we are using PV mechanism instead > of native because PV one performs better. Um. Isn't that the very definition of an optimization? I do think it is better for the essential MMU changes to be clearly separate from the optional ones. David -- 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/