From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B95FAC3279B for ; Fri, 6 Jul 2018 12:49:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 776EA24001 for ; Fri, 6 Jul 2018 12:49:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 776EA24001 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933183AbeGFMtT (ORCPT ); Fri, 6 Jul 2018 08:49:19 -0400 Received: from mga03.intel.com ([134.134.136.65]:57888 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932569AbeGFMtS (ORCPT ); Fri, 6 Jul 2018 08:49:18 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Jul 2018 05:49:17 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,316,1526367600"; d="scan'208";a="69174603" Received: from yhuang-dev.sh.intel.com (HELO yhuang-dev) ([10.239.13.118]) by fmsmga004.fm.intel.com with ESMTP; 06 Jul 2018 05:49:05 -0700 From: "Huang\, Ying" To: Daniel Jordan Cc: Andrew Morton , , , "Kirill A. Shutemov" , Andrea Arcangeli , Michal Hocko , Johannes Weiner , "Shaohua Li" , Hugh Dickins , Minchan Kim , Rik van Riel , Dave Hansen , Naoya Horiguchi , Zi Yan Subject: Re: [PATCH -mm -v4 05/21] mm, THP, swap: Support PMD swap mapping in free_swap_and_cache()/swap_free() References: <20180622035151.6676-1-ying.huang@intel.com> <20180622035151.6676-6-ying.huang@intel.com> <20180705183318.je4gd32awgh2tnb5@ca-dmjordan1.us.oracle.com> Date: Fri, 06 Jul 2018 20:49:05 +0800 In-Reply-To: <20180705183318.je4gd32awgh2tnb5@ca-dmjordan1.us.oracle.com> (Daniel Jordan's message of "Thu, 5 Jul 2018 11:33:18 -0700") Message-ID: <877em8msvy.fsf@yhuang-dev.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Daniel Jordan writes: > On Fri, Jun 22, 2018 at 11:51:35AM +0800, Huang, Ying wrote: >> +static unsigned char swap_free_cluster(struct swap_info_struct *si, >> + swp_entry_t entry) > ... >> + /* Cluster has been split, free each swap entries in cluster */ >> + if (!cluster_is_huge(ci)) { >> + unlock_cluster(ci); >> + for (i = 0; i < SWAPFILE_CLUSTER; i++, entry.val++) { >> + if (!__swap_entry_free(si, entry, 1)) { >> + free_entries++; >> + free_swap_slot(entry); >> + } >> + } > > Is is better on average to use __swap_entry_free_locked instead of > __swap_entry_free here? I'm not sure myself, just asking. > > As it's written, if the cluster's been split, we always take and drop the > cluster lock 512 times, but if we don't expect to call free_swap_slot that > often, then we could just drop and retake the cluster lock inside the innermost > 'if' against the possibility that free_swap_slot eventually makes us take the > cluster lock again. Yes. This is a good idea. Thanks for your suggestion! I will change this in the next version. Best Regards, Huang, Ying > ... >> + return !(free_entries == SWAPFILE_CLUSTER); > > return free_entries != SWAPFILE_CLUSTER;