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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 1A03BC432C3 for ; Sat, 23 Nov 2019 04:54:57 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id AA7D8207DD for ; Sat, 23 Nov 2019 04:54:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AA7D8207DD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 0BC5B6B0542; Fri, 22 Nov 2019 23:54:55 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 06CFA6B0543; Fri, 22 Nov 2019 23:54:55 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EC5256B0544; Fri, 22 Nov 2019 23:54:54 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0007.hostedemail.com [216.40.44.7]) by kanga.kvack.org (Postfix) with ESMTP id D408F6B0542 for ; Fri, 22 Nov 2019 23:54:54 -0500 (EST) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id 821FC8249980 for ; Sat, 23 Nov 2019 04:54:54 +0000 (UTC) X-FDA: 76186327308.25.bite65_821ba254f0a22 X-HE-Tag: bite65_821ba254f0a22 X-Filterd-Recvd-Size: 2286 Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [195.92.253.2]) by imf43.hostedemail.com (Postfix) with ESMTP for ; Sat, 23 Nov 2019 04:54:53 +0000 (UTC) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1iYNRU-0007mm-Bc; Sat, 23 Nov 2019 04:54:44 +0000 Date: Sat, 23 Nov 2019 04:54:44 +0000 From: Al Viro To: Matthew Wilcox Cc: "zhengbin (A)" , Hugh Dickins , linux-mm@kvack.org, linux-kernel@vger.kernel.org, houtao1@huawei.com, yi.zhang@huawei.com, "J. R. Okajima" , Eric Dumazet Subject: Re: [PATCH] tmpfs: use ida to get inode number Message-ID: <20191123045444.GI26530@ZenIV.linux.org.uk> References: <1574259798-144561-1-git-send-email-zhengbin13@huawei.com> <20191120154552.GS20752@bombadil.infradead.org> <1c64e7c2-6460-49cf-6db0-ec5f5f7e09c4@huawei.com> <5423a199-eefb-0a02-6e86-1f6210939c11@huawei.com> <20191122221327.GW20752@bombadil.infradead.org> <77f67d7a-4a93-4319-e6af-54daffcc37e2@huawei.com> <20191123023325.GY20752@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191123023325.GY20752@bombadil.infradead.org> User-Agent: Mutt/1.12.1 (2019-06-15) 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 Fri, Nov 22, 2019 at 06:33:25PM -0800, Matthew Wilcox wrote: > On Sat, Nov 23, 2019 at 10:16:39AM +0800, zhengbin (A) wrote: > > By the way, percpu IDA is for reducing performance impact? This patch has 2.16% > > performance degradation(Use perf to get the cost of ida_alloc_range) > > 2.16% degradation in your tests ... I bet Eric didn't make it so complex > for only 2% performance impact. Unfortunately, he didn't give any > numbers in his patch submission, but it's going to be a bigger problem > on multi-socket machines than on a laptop. It could also be that socket(2) is called (on real loads) just a bit more often than open(2) in a benchmark that tests file creation...