From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751305AbdBTWXx convert rfc822-to-8bit (ORCPT ); Mon, 20 Feb 2017 17:23:53 -0500 Received: from terminus.zytor.com ([65.50.211.136]:39256 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750827AbdBTWXu (ORCPT ); Mon, 20 Feb 2017 17:23:50 -0500 Date: Mon, 20 Feb 2017 14:23:20 -0800 User-Agent: K-9 Mail for Android In-Reply-To: <890292613.23897064.1487628173163.JavaMail.zimbra@redhat.com> References: <38d613dc-5b46-1f4f-04d1-53c01932e6d6@redhat.com> <890292613.23897064.1487628173163.JavaMail.zimbra@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Subject: Re: RFC: Getting rid of LTR in VMX To: Paolo Bonzini , Andy Lutomirski CC: kvm list , linux-kernel@vger.kernel.org, X86 ML , Borislav Petkov From: hpa@zytor.com Message-ID: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On February 20, 2017 2:02:53 PM PST, Paolo Bonzini wrote: > >> > Yes. But 150-200 clock cycles are nothing compared to the cache >misses >> > you get from preemption, so I'd ignore that. Saving 300 clock >cycles on >> > userspace exits from TR+GSBASE would be about 5% on my Haswell. >> >> That's still 5% :) > >Yes, 5% on userspace exits is good (though they're rare). > >OTOH, 300 clock cycles on preemption are nothing to write home about. > >Paolo Oh, I would say it is... especially when it's basically free. -- Sent from my Android device with K-9 Mail. Please excuse my brevity.