From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751743AbdHBXHS (ORCPT ); Wed, 2 Aug 2017 19:07:18 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:58536 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751058AbdHBXHR (ORCPT ); Wed, 2 Aug 2017 19:07:17 -0400 Date: Wed, 2 Aug 2017 16:07:16 -0700 From: Andrew Morton To: Vitaly Wool Cc: Linux-MM , linux-kernel@vger.kernel.org, Dan Streetman , Oleksiy.Avramchenko@sony.com Subject: Re: [PATCH] z3fold: use per-cpu unbuddied lists Message-Id: <20170802160716.f5d1072873799a3a420f6538@linux-foundation.org> In-Reply-To: <20170802122505.e41d5c778a873375bcb0cc19@gmail.com> References: <20170802122505.e41d5c778a873375bcb0cc19@gmail.com> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.23; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2 Aug 2017 12:25:05 +0200 Vitaly Wool wrote: > z3fold is operating on unbuddied lists in a simple manner: in fact, > it only takes the first entry off the list on a hot path. So if the > z3fold pool is big enough and balanced well enough, considering > only the lists local to the current CPU won't be an issue in any > way, while random I/O performance will go up. Has the performance benefit been measured? It's a large patch. > This patch also introduces two worker threads which: one for async > in-page object layout optimization and one for releasing freed > pages. Why? What are the runtime effects of this change? Does this turn currently-synchronous operations into now-async operations? If so, what are the implications of this if, say, the workqueue doesn't get serviced for a while? etc. Sorry, but I'm not seeing anywhere near enough information and testing results to justify merging such a large and intrusive patch.