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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 523FBC433E1 for ; Tue, 18 Aug 2020 03:00:36 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0C52A206DA for ; Tue, 18 Aug 2020 03:00:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="u87PHldg" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0C52A206DA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 91EF56B0002; Mon, 17 Aug 2020 23:00:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8D03F6B0005; Mon, 17 Aug 2020 23:00:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7BE976B0006; Mon, 17 Aug 2020 23:00:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0136.hostedemail.com [216.40.44.136]) by kanga.kvack.org (Postfix) with ESMTP id 6629B6B0002 for ; Mon, 17 Aug 2020 23:00:35 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 16ED1180AD82F for ; Tue, 18 Aug 2020 03:00:35 +0000 (UTC) X-FDA: 77162186430.01.magic50_610113c2701b Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin01.hostedemail.com (Postfix) with ESMTP id DADC7100480D7 for ; Tue, 18 Aug 2020 03:00:34 +0000 (UTC) X-HE-Tag: magic50_610113c2701b X-Filterd-Recvd-Size: 2901 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf24.hostedemail.com (Postfix) with ESMTP for ; Tue, 18 Aug 2020 03:00:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=H/DbB7pBbgOn0Q7tg6eRhr3Ei+qntcmROPbAJdmUrhw=; b=u87PHldgMoutph7ROXXKPW6Net IP4fTTbxnyRR07BhgV6D3YRSO/IxkIO5LkD6I4FuhQ581WaJ9FrcOecpYLCD0UBfjwAJqEi5Q9lRS wNPULqtX27dSr7bHCPBVSwo0G6X1E6TKDENC9lcO+dTtPz9IMZSjb8rv5k5wFPBejOuNUoXTJltIH ug4hv7XNR529sEK0m146F+kViawZ9VJ66neSUMc9ZO6NhUracFmiQN754uqopJvZbYyVUN33sA3bN mGynXKFAflNHpcZHyyw4IOwKmS07Ac8Oyrg0XWsqymRvXNH9IRWxcanOXTrZBhDI18XY0dJFxrcMR dMnlTKYA==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1k7rrJ-0000A0-4D; Tue, 18 Aug 2020 03:00:21 +0000 Date: Tue, 18 Aug 2020 04:00:21 +0100 From: Matthew Wilcox To: John Hubbard Cc: Peter Collingbourne , "Kirill A . Shutemov" , Andrew Morton , Catalin Marinas , Evgenii Stepanov , Linux ARM , linux-mm@kvack.org, kernel test robot , Linux API , linux-doc@vger.kernel.org Subject: Re: [PATCH v3] mm: introduce reference pages Message-ID: <20200818030021.GM17456@casper.infradead.org> References: <20200814213310.42170-1-pcc@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: DADC7100480D7 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 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 Mon, Aug 17, 2020 at 07:31:39PM -0700, John Hubbard wrote: > > Real time (s) Max RSS (KiB) > > anon 2.237081 107088 > > memset 2.252241 112180 > > refpage 2.243786 107128 > > > > We can see that RSS for refpage is almost the same as anon, and real > > time overhead is 44% that of memset. > > > > Are some of the numbers stale, maybe? Try as I might, I cannot combine > anything above to come up with 44%. :) You're not trying hard enough ;-) (2.252241 - 2.237081) / 2.237081 = .00677668801442594166 (2.243786 - 2.237081) / 2.237081 = .00299720930981041812 .00299720930981041812 / .00677668801442594166 = .44228232189973614648 tadaa! As I said last time this was posted, I'm just not excited by this. We go from having a 0.68% time overhead down to an 0.30% overhead, which just doesn't move the needle for me. Maybe there's a better benchmark than this to show benefits from this patchset.