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=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 1DB19C433DF for ; Wed, 3 Jun 2020 22:59:35 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D1787208E4 for ; Wed, 3 Jun 2020 22:59:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="pBakPSiD" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D1787208E4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 72B54280039; Wed, 3 Jun 2020 18:59:34 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 70406280003; Wed, 3 Jun 2020 18:59:34 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 63F89280039; Wed, 3 Jun 2020 18:59:34 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0213.hostedemail.com [216.40.44.213]) by kanga.kvack.org (Postfix) with ESMTP id 4C712280003 for ; Wed, 3 Jun 2020 18:59:34 -0400 (EDT) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 1434B8248D51 for ; Wed, 3 Jun 2020 22:59:34 +0000 (UTC) X-FDA: 76889419068.30.spy69_1944f718bdc56 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin30.hostedemail.com (Postfix) with ESMTP id EE1FE180B3C83 for ; Wed, 3 Jun 2020 22:59:33 +0000 (UTC) X-HE-Tag: spy69_1944f718bdc56 X-Filterd-Recvd-Size: 5350 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf04.hostedemail.com (Postfix) with ESMTP for ; Wed, 3 Jun 2020 22:59:33 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EEC24208C9; Wed, 3 Jun 2020 22:59:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591225172; bh=0k+bIb8mcADjbCjImDNC9x+5alEQbN5ggepSBW/UIWA=; h=Date:From:To:Subject:In-Reply-To:From; b=pBakPSiDh3q4sKTIYdFY73EEb17K5T8cCz1yBZzcZ+UTcAHCAp9e/K1hc1fmZRXUR iPgMaS2dyRb99+yLvYX1EV64brQvWadXF/Amvu4P3t7WgAy2eHPOpdKRM+icCFfnYQ vgbXj3X8RL8RvsaoVrk57Bmi4q6sxZmreg1Tio5A= Date: Wed, 03 Jun 2020 15:59:31 -0700 From: Andrew Morton To: akpm@linux-foundation.org, alex.williamson@redhat.com, alexander.h.duyck@linux.intel.com, corbet@lwn.net, dan.j.williams@intel.com, daniel.m.jordan@oracle.com, dave.hansen@linux.intel.com, david@redhat.com, elliott@hpe.com, herbert@gondor.apana.org.au, jgg@ziepe.ca, josh@joshtriplett.org, ktkhai@virtuozzo.com, linux-mm@kvack.org, mhocko@kernel.org, mm-commits@vger.kernel.org, pasha.tatashin@soleen.com, pavel@ucw.cz, peterz@infradead.org, rdunlap@infradead.org, shile.zhang@linux.alibaba.com, steffen.klassert@secunet.com, steven.sistare@oracle.com, tj@kernel.org, torvalds@linux-foundation.org, ziy@nvidia.com Subject: [patch 052/131] padata: remove exit routine Message-ID: <20200603225931.N3Z8u87O-%akpm@linux-foundation.org> In-Reply-To: <20200603155549.e041363450869eaae4c7f05b@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Queue-Id: EE1FE180B3C83 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 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: From: Daniel Jordan Subject: padata: remove exit routine Patch series "padata: parallelize deferred page init", v3. Deferred struct page init is a bottleneck in kernel boot--the biggest for us and probably others. Optimizing it maximizes availability for large-memory systems and allows spinning up short-lived VMs as needed without having to leave them running. It also benefits bare metal machines hosting VMs that are sensitive to downtime. In projects such as VMM Fast Restart[1], where guest state is preserved across kexec reboot, it helps prevent application and network timeouts in the guests. So, multithread deferred init to take full advantage of system memory bandwidth. Extend padata, a framework that handles many parallel singlethreaded jobs, to handle multithreaded jobs as well by adding support for splitting up the work evenly, specifying a minimum amount of work that's appropriate for one helper thread to do, load balancing between helpers, and coordinating them. More documentation in patches 4 and 8. This series is the first step in a project to address other memory proportional bottlenecks in the kernel such as pmem struct page init, vfio page pinning, hugetlb fallocate, and munmap. Deferred page init doesn't require concurrency limits, resource control, or priority adjustments like these other users will because it happens during boot when the system is otherwise idle and waiting for page init to finish. This has been run on a variety of x86 systems and speeds up kernel boot by 4% to 49%, saving up to 1.6 out of 4 seconds. Patch 6 has more numbers. This patch (of 8): padata_driver_exit() is unnecessary because padata isn't built as a module and doesn't exit. padata's init routine will soon allocate memory, so getting rid of the exit function now avoids pointless code to free it. Link: http://lkml.kernel.org/r/20200527173608.2885243-1-daniel.m.jordan@oracle.com Link: http://lkml.kernel.org/r/20200527173608.2885243-2-daniel.m.jordan@oracle.com Signed-off-by: Daniel Jordan Tested-by: Josh Triplett Cc: Alexander Duyck Cc: Alex Williamson Cc: Dan Williams Cc: Dave Hansen Cc: David Hildenbrand Cc: Herbert Xu Cc: Jason Gunthorpe Cc: Jonathan Corbet Cc: Kirill Tkhai Cc: Michal Hocko Cc: Pavel Machek Cc: Pavel Tatashin Cc: Peter Zijlstra Cc: Randy Dunlap Cc: Robert Elliott Cc: Shile Zhang Cc: Steffen Klassert Cc: Steven Sistare Cc: Tejun Heo Cc: Zi Yan Signed-off-by: Andrew Morton --- kernel/padata.c | 6 ------ 1 file changed, 6 deletions(-) --- a/kernel/padata.c~padata-remove-exit-routine +++ a/kernel/padata.c @@ -1074,10 +1074,4 @@ static __init int padata_driver_init(voi } module_init(padata_driver_init); -static __exit void padata_driver_exit(void) -{ - cpuhp_remove_multi_state(CPUHP_PADATA_DEAD); - cpuhp_remove_multi_state(hp_online); -} -module_exit(padata_driver_exit); #endif _