From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753028AbbAVQTs (ORCPT ); Thu, 22 Jan 2015 11:19:48 -0500 Received: from smtp2.provo.novell.com ([137.65.250.81]:57136 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752008AbbAVQTr (ORCPT ); Thu, 22 Jan 2015 11:19:47 -0500 Message-ID: <1421943573.4903.24.camel@stgolabs.net> Subject: Re: [PATCH] mm, vmacache: Add kconfig VMACACHE_SHIFT From: Davidlohr Bueso To: WANG Chao Cc: Andrew Morton , Ingo Molnar , Peter Zijlstra , Michel Lespinasse , Rik van Riel , Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org Date: Thu, 22 Jan 2015 08:19:33 -0800 In-Reply-To: <20150122075742.GA11335@dhcp-129-179.nay.redhat.com> References: <1421908189-18938-1-git-send-email-chaowang@redhat.com> <1421912761.4903.22.camel@stgolabs.net> <20150122075742.GA11335@dhcp-129-179.nay.redhat.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.7 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2015-01-22 at 15:57 +0800, WANG Chao wrote: > Hi, Davidlohr > > On 01/21/15 at 11:46pm, Davidlohr Bueso wrote: > > On Thu, 2015-01-22 at 14:29 +0800, WANG Chao wrote: > > > Add a new kconfig option VMACACHE_SHIFT (as a power of 2) to specify the > > > number of slots vma cache has for each thread. Range is chosen 0-4 (1-16 > > > slots) to consider both overhead and performance penalty. Default is 2 > > > (4 slots) as it originally is, which provides good enough balance. > > > > > > > Nack. I don't feel comfortable making scalability features of core code > > configurable. > > Out of respect, is this a general rule not making scalability features > of core code configurable? I doubt its a rule, just common sense. Users have no business configuring such low level details. The optimizations need to transparently work for everyone. Thanks, Davidlohr