From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zachary Amsden Subject: Re: [patch 13/26] Xen-paravirt_ops: Consistently wrap paravirt ops callsites to make them patchable Date: Tue, 20 Mar 2007 11:54:25 -0800 Message-ID: <46003BF1.4090601@vmware.com> References: <20070318120814.GA45869@muc.de> <1174272469.11680.23.camel@localhost.localdomain> <1174348905.11680.54.camel@localhost.localdomain> <45FF4043.4000805@vmware.com> <45FF770C.7050301@goop.org> <20070320192818.GA87860@muc.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Linus Torvalds , "Eric W. Biederman" , Jeremy Fitzhardinge , 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, anthony@codemonkey.ws, netdev@vger.kernel.org To: Andi Kleen Return-path: Received: from smtp-outbound-1.vmware.com ([65.113.40.141]:36051 "EHLO smtp-outbound-1.vmware.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753296AbXCTTy0 (ORCPT ); Tue, 20 Mar 2007 15:54:26 -0400 In-Reply-To: <20070320192818.GA87860@muc.de> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Andi Kleen wrote: > One thing I was pondering was to replace the expensive popfs with > > bt $IF,(%rsp) > jnc 1f > sti > 1: > > But would be mostly a P4 optimization again and I'm not 100% sure it is > worth it. > Worth it on 32-bit. On AMD64, probably not. On Intel 64-bit, maybe, but less important than in P4 days. This could change character completely if used at the tail of a function where you now have sti; 1: ret Which generates an interrupt holdoff on the ret, an unusual thing to do. Zach