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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,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 E110AC352BE for ; Tue, 14 Apr 2020 17:41:11 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A22C12054F for ; Tue, 14 Apr 2020 17:41:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="b38E4/L2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A22C12054F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=oracle.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 393CF8E0035; Tue, 14 Apr 2020 13:41:11 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 343BC8E0001; Tue, 14 Apr 2020 13:41:11 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 232648E0035; Tue, 14 Apr 2020 13:41:11 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0058.hostedemail.com [216.40.44.58]) by kanga.kvack.org (Postfix) with ESMTP id 086E58E0001 for ; Tue, 14 Apr 2020 13:41:11 -0400 (EDT) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 8A82F4DC1 for ; Tue, 14 Apr 2020 17:41:10 +0000 (UTC) X-FDA: 76707176700.13.sink43_a2d5c551f630 X-HE-Tag: sink43_a2d5c551f630 X-Filterd-Recvd-Size: 4529 Received: from userp2130.oracle.com (userp2130.oracle.com [156.151.31.86]) by imf25.hostedemail.com (Postfix) with ESMTP for ; Tue, 14 Apr 2020 17:41:09 +0000 (UTC) Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 03EHefDT189514; Tue, 14 Apr 2020 17:41:06 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2020-01-29; bh=2u650jyBYPYWSkxnqM771FUyNRR6mExgvx23OadXB4Y=; b=b38E4/L2OyFJx51scuuI4RYasQMyN++sXYX1hXSM5evsvjespyVzuxtbXZ4wD2RBoinm /7Qt/UTNNU4EynhUfnmL5K0DOxpkNyqoW7qncOlFnNZyHdYgRTSxI7RB8+RmlyY5cg5C XTRR8NRGv0bfU7WKNTo5+mUfgNHxgKewAIkBaCYsZp9iODQ2wNO8UTRioG6IrSTQBr2K HnR+v52XCcP92toNbOV2/aWM33X4ev9/MIb3u8eydpkOlOTRDpe1ENdD9nkfsJ16NSDe I+qvM54umGlPKBfQ7JB1IQo2h+lliu2PtZnUnlN40jupJn3lxmR9xrdFVr+681nJpbXB KA== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by userp2130.oracle.com with ESMTP id 30b5ar69qu-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 14 Apr 2020 17:41:05 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 03EHbCxL044057; Tue, 14 Apr 2020 17:41:05 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userp3020.oracle.com with ESMTP id 30bqm2ecvt-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 14 Apr 2020 17:41:05 +0000 Received: from abhmp0009.oracle.com (abhmp0009.oracle.com [141.146.116.15]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 03EHf19F019209; Tue, 14 Apr 2020 17:41:02 GMT Received: from ca-dmjordan1.us.oracle.com (/10.211.9.48) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 14 Apr 2020 10:41:01 -0700 Date: Tue, 14 Apr 2020 13:41:20 -0400 From: Daniel Jordan To: Michal Hocko Cc: Prathu Baronia , alexander.duyck@gmail.com, chintan.pandya@oneplus.com, ying.huang@intel.com, akpm@linux-foundation.com, linux-mm@kvack.org, gregkh@linuxfoundation.com, gthelen@google.com, jack@suse.cz, ken.lin@oneplus.com, gasine.xu@oneplus.com Subject: Re: [PATCH v2] mm: Optimized hugepage zeroing & copying from user Message-ID: <20200414174120.pufhdh3i5thro6pq@ca-dmjordan1.us.oracle.com> References: <20200414153829.GA15230@oneplus.com> <20200414170312.GR4629@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200414170312.GR4629@dhcp22.suse.cz> User-Agent: NeoMutt/20180716 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9591 signatures=668686 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 mlxlogscore=736 adultscore=0 mlxscore=0 phishscore=0 malwarescore=0 spamscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004140131 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9591 signatures=668686 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 malwarescore=0 spamscore=0 phishscore=0 mlxlogscore=804 suspectscore=0 adultscore=0 mlxscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004140131 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 Tue, Apr 14, 2020 at 07:03:12PM +0200, Michal Hocko wrote: > On Tue 14-04-20 21:08:32, Prathu Baronia wrote: > > In !HIGHMEM cases, specially in 64-bit architectures, we don't need temp mapping > > of pages. Hence, k(map|unmap)_atomic() acts as nothing more than multiple > > barrier() calls, for example for a 2MB hugepage in clear_huge_page() these are > > called 512 times i.e. to map and unmap each subpage that means in total 2048 > > barrier calls. I think barrier() only matters at compile time. > > This called for optimization. Simply getting VADDR from page does > > the job for us. This also applies to the copy_user_huge_page() function. > > I still have hard time to see why kmap machinery should introduce any > slowdown here. Previous data posted while discussing v1 didn't really > show anything outside of the noise. Maybe pagefault_disable/enable are barely showing up. Alternatively, do you have CONFIG_PREEMPT_COUNT enabled?