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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 9B1F6C47404 for ; Fri, 4 Oct 2019 10:11:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2DAA520867 for ; Fri, 4 Oct 2019 10:11:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b="sG3VQOPv" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2DAA520867 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=yandex-team.ru Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 8948B6B0003; Fri, 4 Oct 2019 06:11:11 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 844FA6B0005; Fri, 4 Oct 2019 06:11:11 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 75AAD6B0007; Fri, 4 Oct 2019 06:11:11 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0140.hostedemail.com [216.40.44.140]) by kanga.kvack.org (Postfix) with ESMTP id 550576B0003 for ; Fri, 4 Oct 2019 06:11:11 -0400 (EDT) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id F03BC3A91 for ; Fri, 4 Oct 2019 10:11:10 +0000 (UTC) X-FDA: 76005684300.07.talk42_7e9ce8b9d5d00 X-HE-Tag: talk42_7e9ce8b9d5d00 X-Filterd-Recvd-Size: 3267 Received: from forwardcorp1p.mail.yandex.net (forwardcorp1p.mail.yandex.net [77.88.29.217]) by imf45.hostedemail.com (Postfix) with ESMTP for ; Fri, 4 Oct 2019 10:11:09 +0000 (UTC) Received: from mxbackcorp1g.mail.yandex.net (mxbackcorp1g.mail.yandex.net [IPv6:2a02:6b8:0:1402::301]) by forwardcorp1p.mail.yandex.net (Yandex) with ESMTP id 7E3762E1545; Fri, 4 Oct 2019 13:11:07 +0300 (MSK) Received: from sas1-7fab0cd91cd2.qloud-c.yandex.net (sas1-7fab0cd91cd2.qloud-c.yandex.net [2a02:6b8:c14:3a93:0:640:7fab:cd9]) by mxbackcorp1g.mail.yandex.net (nwsmtp/Yandex) with ESMTP id i8ZLUyF8I0-B7V04XEn; Fri, 04 Oct 2019 13:11:07 +0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1570183867; bh=PEYRkN66e68K53kXPyUEIyZkiKjZur7yGuoDnwzr2F0=; h=Message-ID:Date:To:From:Subject:Cc; b=sG3VQOPvxmc61Ka4gpqd4ZNGBXMx2iWNPnajqO8tOJyWFjb7NDC9oNS7ECkObE2LU g3bGdWuYKQwj8HfJRhUhvIR9XjB5YPgEtpku4uq9SDA3saUrZi2aybCuzhO9/aiqTB g32O9UizWQeKHikZd5aw4lMPm8D1+emShyu0DISs= Authentication-Results: mxbackcorp1g.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Received: from dynamic-red.dhcp.yndx.net (dynamic-red.dhcp.yndx.net [2a02:6b8:0:40c:3d4d:a9cb:ef29:4bb1]) by sas1-7fab0cd91cd2.qloud-c.yandex.net (nwsmtp/Yandex) with ESMTPSA id 2MUv2d990q-B6I0fpBf; Fri, 04 Oct 2019 13:11:06 +0300 (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client certificate not present) Subject: [PATCH] mm/swap: piggyback lru_add_drain_all() calls From: Konstantin Khlebnikov To: linux-mm@kvack.org, Andrew Morton Cc: linux-kernel@vger.kernel.org Date: Fri, 04 Oct 2019 13:11:06 +0300 Message-ID: <157018386639.6110.3058050375244904201.stgit@buzz> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: This is very slow operation. There is no reason to do it again if somebody else already drained all per-cpu vectors after we waited for lock. Signed-off-by: Konstantin Khlebnikov --- mm/swap.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/mm/swap.c b/mm/swap.c index 38c3fa4308e2..6203918e1316 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -708,9 +708,10 @@ static void lru_add_drain_per_cpu(struct work_struct *dummy) */ void lru_add_drain_all(void) { + static seqcount_t seqcount = SEQCNT_ZERO(seqcount); static DEFINE_MUTEX(lock); static struct cpumask has_work; - int cpu; + int cpu, seq; /* * Make sure nobody triggers this path before mm_percpu_wq is fully @@ -719,7 +720,16 @@ void lru_add_drain_all(void) if (WARN_ON(!mm_percpu_wq)) return; + seq = raw_read_seqcount_latch(&seqcount); + mutex_lock(&lock); + + /* Piggyback on drain done by somebody else. */ + if (__read_seqcount_retry(&seqcount, seq)) + goto done; + + raw_write_seqcount_latch(&seqcount); + cpumask_clear(&has_work); for_each_online_cpu(cpu) { @@ -740,6 +750,7 @@ void lru_add_drain_all(void) for_each_cpu(cpu, &has_work) flush_work(&per_cpu(lru_add_drain_work, cpu)); +done: mutex_unlock(&lock); } #else