Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752651AbdFNWS2 (ORCPT ); Wed, 14 Jun 2017 18:18:28 -0400 Received: from mga06.intel.com ([134.134.136.31]:1677 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751606AbdFNWS1 (ORCPT ); Wed, 14 Jun 2017 18:18:27 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.39,341,1493708400"; d="scan'208";a="980954749" Subject: Re: [PATCH v2 00/10] PCID and improved laziness To: Andy Lutomirski , x86@kernel.org References: Cc: linux-kernel@vger.kernel.org, Borislav Petkov , Linus Torvalds , Andrew Morton , Mel Gorman , "linux-mm@kvack.org" , Nadav Amit , Rik van Riel , Arjan van de Ven , Peter Zijlstra From: Dave Hansen Message-ID: <6da4aea9-ef52-694d-9a03-285c32018326@intel.com> Date: Wed, 14 Jun 2017 15:18:26 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 636 Lines: 12 On 06/13/2017 09:56 PM, Andy Lutomirski wrote: > 2. Mms that have been used recently on a given CPU might get to keep > their TLB entries alive across process switches with this patch > set. TLB fills are pretty fast on modern CPUs, but they're even > faster when they don't happen. Let's not forget that TLBs are also getting bigger. The bigger TLBs help ensure that they *can* survive across another process's timeslice. Also, the cost to refill the paging structure caches is going up. Just think of how many cachelines you have to pull in to populate a ~1500-entry TLB, even if the CPU hid the latency of those loads.