Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932326AbaAIUNN (ORCPT ); Thu, 9 Jan 2014 15:13:13 -0500 Received: from mx1.redhat.com ([209.132.183.28]:12760 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756643AbaAIUNI (ORCPT ); Thu, 9 Jan 2014 15:13:08 -0500 Message-ID: <52CEFD4F.3080804@redhat.com> Date: Thu, 09 Jan 2014 14:49:35 -0500 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Mel Gorman , Alex Shi , Ingo Molnar CC: Linus Torvalds , Thomas Gleixner , Andrew Morton , Fengguang Wu , H Peter Anvin , Linux-X86 , Linux-MM , LKML Subject: Re: [PATCH 3/5] x86: mm: Eliminate redundant page table walk during TLB range flushing References: <1389278098-27154-1-git-send-email-mgorman@suse.de> <1389278098-27154-4-git-send-email-mgorman@suse.de> In-Reply-To: <1389278098-27154-4-git-send-email-mgorman@suse.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/09/2014 09:34 AM, Mel Gorman wrote: > When choosing between doing an address space or ranged flush, the x86 > implementation of flush_tlb_mm_range takes into account whether there are > any large pages in the range. A per-page flush typically requires fewer > entries than would covered by a single large page and the check is redundant. > > There is one potential exception. THP migration flushes single THP entries > and it conceivably would benefit from flushing a single entry instead > of the mm. However, this flush is after a THP allocation, copy and page > table update potentially with any other threads serialised behind it. In > comparison to that, the flush is noise. It makes more sense to optimise > balancing to require fewer flushes than to optimise the flush itself. > > This patch deletes the redundant huge page check. > > Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/