Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764282AbcLUTuy (ORCPT ); Wed, 21 Dec 2016 14:50:54 -0500 Received: from mail-io0-f193.google.com ([209.85.223.193]:34680 "EHLO mail-io0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754344AbcLUTuv (ORCPT ); Wed, 21 Dec 2016 14:50:51 -0500 MIME-Version: 1.0 In-Reply-To: <20161222050130.49d93982@roar.ozlabs.ibm.com> References: <20161219225826.F8CB356F@viggo.jf.intel.com> <156a5b34-ad3b-d0aa-83c9-109b366c1bdf@linux.intel.com> <20161221080931.GQ3124@twins.programming.kicks-ass.net> <20161221083247.GW3174@twins.programming.kicks-ass.net> <20161222043331.31aab9cc@roar.ozlabs.ibm.com> <20161222050130.49d93982@roar.ozlabs.ibm.com> From: Linus Torvalds Date: Wed, 21 Dec 2016 11:50:49 -0800 X-Google-Sender-Auth: 7Hi3qr03cQr-zTJ61FAZOrDEzyA Message-ID: Subject: Re: [RFC][PATCH] make global bitlock waitqueues per-node To: Nicholas Piggin Cc: Peter Zijlstra , Dave Hansen , Bob Peterson , Linux Kernel Mailing List , Steven Whitehouse , Andrew Lutomirski , Andreas Gruenbacher , Mel Gorman , linux-mm , Hugh Dickins Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 763 Lines: 18 On Wed, Dec 21, 2016 at 11:01 AM, Nicholas Piggin wrote: > Peter's patch is less code and in that regard a bit nicer. I tried > going that way once, but I just thought it was a bit too sloppy to > do nicely with wait bit APIs. So I have to admit that when I read through your and PeterZ's patches back-to-back, yours was easier to understand. PeterZ's is smaller but kind of subtle. The whole "return zero from lock_page_wait() and go around again" and the locking around that isn't exactly clear. In contrast, yours has the obvious waitqueue spinlock. I'll think about it. And yes, it would be good to have more testing, but at the same time xmas is imminent, and waiting around too much isn't going to help either.. Linus