From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f173.google.com (mail-pf0-f173.google.com [209.85.192.173]) by kanga.kvack.org (Postfix) with ESMTP id 475FA828DF for ; Wed, 13 Jan 2016 18:56:18 -0500 (EST) Received: by mail-pf0-f173.google.com with SMTP id e65so89470466pfe.0 for ; Wed, 13 Jan 2016 15:56:18 -0800 (PST) Received: from mga14.intel.com (mga14.intel.com. [192.55.52.115]) by mx.google.com with ESMTP id y11si5086103pas.239.2016.01.13.15.56.17 for ; Wed, 13 Jan 2016 15:56:17 -0800 (PST) Subject: Re: [RFC 09/13] x86/mm: Disable interrupts when flushing the TLB using CR3 References: <5696E129.9000804@linux.intel.com> From: Dave Hansen Message-ID: <5696E420.9040704@linux.intel.com> Date: Wed, 13 Jan 2016 15:56:16 -0800 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andy Lutomirski Cc: Linus Torvalds , Oleg Nesterov , X86 ML , Borislav Petkov , Linux Kernel Mailing List , "linux-mm@kvack.org" , Brian Gerst On 01/13/2016 03:51 PM, Andy Lutomirski wrote: > On Wed, Jan 13, 2016 at 3:43 PM, Dave Hansen > wrote: >> On 01/13/2016 03:35 PM, Andy Lutomirski wrote: >>> Can anyone here ask a hardware or microcode person what's going on >>> with CR3 writes possibly being faster than INVPCID? Is there some >>> trick to it? >> >> I just went and measured it myself this morning. "INVPCID Type 3" (all >> contexts no global) on a Skylake system was 15% slower than a CR3 write. >> >> Is that in the same ballpark from what you've observed? > > It's similar, except that I was comparing "INVPCID Type 1" (single > context no globals) to a CR3 write. Ahh, because you're using PCID... That one I saw as being ~1.85x the number of cycles that a CR3 write was. > Type 2, at least, is dramatically faster than the pair of CR4 writes > it replaces. Yeah, I saw the same thing. Type 2 was ~2.4x faster than the CR4 writes. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org