Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932134AbdC2Qzg (ORCPT ); Wed, 29 Mar 2017 12:55:36 -0400 Received: from gum.cmpxchg.org ([85.214.110.215]:42716 "EHLO gum.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751834AbdC2Qze (ORCPT ); Wed, 29 Mar 2017 12:55:34 -0400 Date: Wed, 29 Mar 2017 12:55:22 -0400 From: Johannes Weiner To: "Huang, Ying" Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hugh Dickins , Shaohua Li , Minchan Kim , Rik van Riel Subject: Re: [PATCH -mm -v7 1/9] mm, swap: Make swap cluster size same of THP size on x86_64 Message-ID: <20170329165522.GA31821@cmpxchg.org> References: <20170328053209.25876-1-ying.huang@intel.com> <20170328053209.25876-2-ying.huang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170328053209.25876-2-ying.huang@intel.com> User-Agent: Mutt/1.8.0 (2017-02-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 828 Lines: 29 On Tue, Mar 28, 2017 at 01:32:01PM +0800, Huang, Ying wrote: > @@ -499,6 +499,19 @@ config FRONTSWAP > > If unsure, say Y to enable frontswap. > > +config ARCH_USES_THP_SWAP_CLUSTER > + bool > + default n This is fine. > +config THP_SWAP_CLUSTER > + bool > + depends on SWAP && TRANSPARENT_HUGEPAGE && ARCH_USES_THP_SWAP_CLUSTER > + default y > + help > + Use one swap cluster to hold the contents of the THP > + (Transparent Huge Page) swapped out. The size of the swap > + cluster will be same as that of THP. But this is a super weird thing to ask the user. How would they know what to say, if we don't know? I don't think this should be a config knob at all. Merge the two config items into a simple config THP_SWAP_CLUSTER bool default n and let the archs with reasonable THP sizes select it.