From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [patch 13/26] Xen-paravirt_ops: Consistently wrap paravirt ops callsites to make them patchable Date: 20 Mar 2007 00:42:48 +0100 Message-ID: <20070319234248.GA93348@muc.de> References: <20070316.023331.59468179.davem@davemloft.net> <45FB005D.9060809@goop.org> <1174127638.8897.75.camel@localhost.localdomain> <20070318.003309.71088169.davem@davemloft.net> <20070318120814.GA45869@muc.de> <1174272469.11680.23.camel@localhost.localdomain> <45FEE010.1050103@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "Eric W. Biederman" , Rusty Russell , David Miller , mingo@elte.hu, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, virtualization@lists.osdl.org, xen-devel@lists.xensource.com, chrisw@sous-sol.org, zach@vmware.com, anthony@codemonkey.ws, torvalds@linux-foundation.org, netdev@vger.kernel.org To: Jeremy Fitzhardinge Return-path: Received: from colin.muc.de ([193.149.48.1]:1999 "EHLO mail.muc.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964785AbXCSXmu (ORCPT ); Mon, 19 Mar 2007 19:42:50 -0400 Date: Tue, 20 Mar 2007 00:42:48 +0100 Content-Disposition: inline In-Reply-To: <45FEE010.1050103@goop.org> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org > Possibly not, but I'd like to be able to say with confidence that > running a PARAVIRT kernel on bare hardware has no performance loss > compared to running a !PARAVIRT kernel. There's the case of small > instruction sequences which have been replaced with calls (such as > sti/cli/push;popf/etc), My guess is that most critical pushf/popf are in spin_lock_irqsave(). It would be possible to special case that one -- inline it -- and use out of line versions for all the others. -Andi