From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f70.google.com (mail-wm0-f70.google.com [74.125.82.70]) by kanga.kvack.org (Postfix) with ESMTP id 9FCBB6B039F for ; Fri, 31 Mar 2017 10:56:23 -0400 (EDT) Received: by mail-wm0-f70.google.com with SMTP id h188so54413wma.4 for ; Fri, 31 Mar 2017 07:56:23 -0700 (PDT) Received: from gum.cmpxchg.org (gum.cmpxchg.org. [85.214.110.215]) by mx.google.com with ESMTPS id q52si8483548wrb.280.2017.03.31.07.56.22 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 31 Mar 2017 07:56:22 -0700 (PDT) Date: Fri, 31 Mar 2017 10:56:17 -0400 From: Johannes Weiner Subject: Re: [PATCH -mm -v7 1/9] mm, swap: Make swap cluster size same of THP size on x86_64 Message-ID: <20170331145617.GB6408@cmpxchg.org> References: <20170328053209.25876-1-ying.huang@intel.com> <20170328053209.25876-2-ying.huang@intel.com> <20170329165522.GA31821@cmpxchg.org> <87o9wjtwvv.fsf@yhuang-dev.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87o9wjtwvv.fsf@yhuang-dev.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: "Huang, Ying" Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hugh Dickins , Shaohua Li , Minchan Kim , Rik van Riel On Thu, Mar 30, 2017 at 08:45:56AM +0800, Huang, Ying wrote: > Johannes Weiner writes: > > > 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 > > The user will not see this, because there is no string after "bool" to > let user to select it. The help here is for document only, so that > architecture developers could know what this is for. Oh, I missed that. My bad! > > config THP_SWAP_CLUSTER > > bool > > default n > > > > and let the archs with reasonable THP sizes select it. > > This will have same effect as the original solution except the document > is removed. Then I still don't understand why we need two config symbols. Can't archs select the documented THP_SWAP_CLUSTER directly? The #ifdef in swapfile.c could check THP && THP_SWAP_CLUSTER. Am I missing something? -- 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