From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f72.google.com (mail-lf0-f72.google.com [209.85.215.72]) by kanga.kvack.org (Postfix) with ESMTP id C16A56B0005 for ; Thu, 9 Jun 2016 09:32:17 -0400 (EDT) Received: by mail-lf0-f72.google.com with SMTP id u74so17863772lff.0 for ; Thu, 09 Jun 2016 06:32:17 -0700 (PDT) Received: from gum.cmpxchg.org (gum.cmpxchg.org. [85.214.110.215]) by mx.google.com with ESMTPS id r65si19942598wmd.82.2016.06.09.06.32.16 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 09 Jun 2016 06:32:16 -0700 (PDT) Date: Thu, 9 Jun 2016 09:32:05 -0400 From: Johannes Weiner Subject: Re: [PATCH 01/10] mm: allow swappiness that prefers anon over file Message-ID: <20160609133205.GA11719@cmpxchg.org> References: <20160606194836.3624-1-hannes@cmpxchg.org> <20160606194836.3624-2-hannes@cmpxchg.org> <20160607002550.GA26230@bbox> <20160607141818.GE9978@cmpxchg.org> <20160608000632.GA27258@bbox> <20160608155812.GC6727@cmpxchg.org> <20160609010107.GF28620@bbox> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160609010107.GF28620@bbox> Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Rik van Riel , Mel Gorman , Andrea Arcangeli , Andi Kleen , Michal Hocko , Tim Chen , kernel-team@fb.com On Thu, Jun 09, 2016 at 10:01:07AM +0900, Minchan Kim wrote: > A system has big HDD storage and SSD swap. > > HDD: 200 IOPS > SSD: 100000 IOPS > From https://en.wikipedia.org/wiki/IOPS > > So, speed gap is 500x. > x + 500x = 200 > If we use PCIe-SSD, the gap will be larger. > That's why I said 200 is enough to represent speed gap. Ah, I see what you're saying. Yeah, that's unfortunately a limitation in the current ABI. Extending the range to previously unavailable settings is doable; changing the meaning of existing values is not. We'd have to add another interface. > Such system configuration is already non-sense so it is okay to ignore such > usecases? I'm not sure we have to be proactive about it, but we can always add a more fine-grained knob to override swappiness when somebody wants to use such a setup in practice. -- 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