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=-17.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 9B272C433E0 for ; Thu, 14 Jan 2021 12:32:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id F33F923A52 for ; Thu, 14 Jan 2021 12:32:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F33F923A52 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 138C78D00DD; Thu, 14 Jan 2021 07:32:11 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0C0FD8D008E; Thu, 14 Jan 2021 07:32:11 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ECA888D00DD; Thu, 14 Jan 2021 07:32:10 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0251.hostedemail.com [216.40.44.251]) by kanga.kvack.org (Postfix) with ESMTP id D206F8D008E for ; Thu, 14 Jan 2021 07:32:10 -0500 (EST) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 8EA1A181AEF39 for ; Thu, 14 Jan 2021 12:32:10 +0000 (UTC) X-FDA: 77704318020.22.birds19_280238327526 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin22.hostedemail.com (Postfix) with ESMTP id 67E1C18018515 for ; Thu, 14 Jan 2021 12:32:10 +0000 (UTC) X-HE-Tag: birds19_280238327526 X-Filterd-Recvd-Size: 3295 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by imf14.hostedemail.com (Postfix) with ESMTP for ; Thu, 14 Jan 2021 12:32:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1610627529; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=kqjCszUFLRFHXNLR1FXDgMu2Y+ZUpN6PZwYGZFX1IhM=; b=TD7fvLgJ/UE+KFeNQpXEejjUYSgZLXOsA297XVaLccJngRGn/1ILWxEeWSIhJeOBfUJl6g zpU0dNw6PGx2nJ9lWW2RuOpC4H0NOuBsJaExEP/lMr3SN9QjHoDEeh+8CxzWpU2WSB2gpW gtEXtJ+sgF2PJ/q48MMbVIYqCsyJjrQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-181-r1hy61doMz-IppyJS0ejYQ-1; Thu, 14 Jan 2021 07:32:07 -0500 X-MC-Unique: r1hy61doMz-IppyJS0ejYQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CF005107ACF7; Thu, 14 Jan 2021 12:32:05 +0000 (UTC) Received: from [10.36.115.75] (ovpn-115-75.ams2.redhat.com [10.36.115.75]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6C8B060C64; Thu, 14 Jan 2021 12:32:04 +0000 (UTC) Subject: Re: [PATCH] mm/hugetlb: avoid unnecessary hugetlb_acct_memory() call To: Miaohe Lin , akpm@linux-foundation.org, mike.kravetz@oracle.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20210114113140.23069-1-linmiaohe@huawei.com> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <853d6aa4-b84c-7ac2-00d4-402893fcf6b3@redhat.com> Date: Thu, 14 Jan 2021 13:32:03 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <20210114113140.23069-1-linmiaohe@huawei.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 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: On 14.01.21 12:31, Miaohe Lin wrote: > When gbl_reserve is 0, hugetlb_acct_memory() will do nothing except holding > and releasing hugetlb_lock. So, what's the deal then? Adding more code? If this is a performance improvement, we should spell it out. Otherwise I don't see a real benefit of this patch. > > Signed-off-by: Miaohe Lin > --- > mm/hugetlb.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 737b2dce19e6..fe2da9ad6233 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -5241,7 +5241,8 @@ long hugetlb_unreserve_pages(struct inode *inode, long start, long end, > * reservations to be released may be adjusted. > */ > gbl_reserve = hugepage_subpool_put_pages(spool, (chg - freed)); > - hugetlb_acct_memory(h, -gbl_reserve); > + if (gbl_reserve) > + hugetlb_acct_memory(h, -gbl_reserve); > > return 0; > } > -- Thanks, David / dhildenb