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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4A4BEC77B61 for ; Mon, 24 Apr 2023 08:55:26 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C1A8F6B0071; Mon, 24 Apr 2023 04:55:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BA2B26B0074; Mon, 24 Apr 2023 04:55:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A430F6B0075; Mon, 24 Apr 2023 04:55:25 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 902D16B0071 for ; Mon, 24 Apr 2023 04:55:25 -0400 (EDT) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 576E5C01E8 for ; Mon, 24 Apr 2023 08:55:25 +0000 (UTC) X-FDA: 80715675810.01.086F148 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf07.hostedemail.com (Postfix) with ESMTP id 7FDAC40005 for ; Mon, 24 Apr 2023 08:55:23 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=FtbjvgQw; spf=pass (imf07.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mhocko@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1682326523; h=from:from:sender: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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=FUWSITPFyHyJZHRzOJ7p0HDNIrOv1tTlFAivyEtdOd0=; b=2UibwLL6lPx+TczAdmiYTfzIa5PFWh/IuFbIRfjegujCjlod5HvGtu9+fz7S7LEbUsfZod XrdUmBvzVhVFOLbB5E/LUWk7RDSQ3L9pIY1yBirOyqsWQ3wICenRHi/XlfYEMdj4rJ3goa A9PeDRlR7jmGCRlzmctT4drx5t7m1Mw= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=FtbjvgQw; spf=pass (imf07.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mhocko@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1682326523; a=rsa-sha256; cv=none; b=RXNnjHEoL46iZtX/Gqm086SX5KpUvMzFiWYD7AaWBxftKj4pED6pBrocI8f1tKpiGvKjPH IK5GVZ0sFgBsaw/oyjH2CHMVT7sdR3BywvbOgTD5joZFHbGV3AbD+7J1IAXsc0UAFm1J2E VV/xViKqWjGdyv+rCx3Ci8kGufTFXt8= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id D1B511FD7D; Mon, 24 Apr 2023 08:55:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1682326521; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=FUWSITPFyHyJZHRzOJ7p0HDNIrOv1tTlFAivyEtdOd0=; b=FtbjvgQw8fZasiciHehEJTJ+yuklnI4mZn5YduvaM15kpe4JcY0DYOvKCzOy8EqZiE7L1o aGVQscuZkMLxQreS0MuWShx0EIfMDuHtlXnH2wyXC59olFgTIG6ONL3hhBX5VifKsNF2yc n53jD90LbYT4FYWbMKwAwYLHLkPeCP4= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id AB62F13780; Mon, 24 Apr 2023 08:55:21 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id ORNcJ/lDRmQ5dwAAMHmgww (envelope-from ); Mon, 24 Apr 2023 08:55:21 +0000 Date: Mon, 24 Apr 2023 10:55:20 +0200 From: Michal Hocko To: Uladzislau Rezki Cc: lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org Subject: Re: [Lsf-pc] LSFMMBPF proposal [MM]: Eliminate vmap/vmalloc lock contention Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 7FDAC40005 X-Stat-Signature: ss9yhydf4w98bceotni7ewimt9aggah9 X-Rspam-User: X-HE-Tag: 1682326523-921664 X-HE-Meta: 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 mB2B4cDY tUswO4T57uGkd1L6/gyALzmaWjFG9CEXG9RGmhQ6aZIB245Gzf73lSxrZaNsGG1PSbSjYA5qKxKVP9fhmuzcsChMqOi8/Rr2bEo6gb/61YXWcOVcUNCoKTUIDEj2F2g+Yj88SkyVD9gI93HXZP3okoj8W9Q== 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 24-04-23 09:44:00, Uladzislau Rezki wrote: > On Fri, Apr 21, 2023 at 02:03:43PM +0200, Michal Hocko wrote: > > On Tue 28-02-23 17:42:43, Uladzislau Rezki wrote: > > > Hello, LSF. > > > > > > Title: Introduce a per-cpu-vmap-cache to eliminate a vmap lock contention > > > > > > Description: > > > Currently the vmap code is not scaled to number of CPU cores in a system > > > because a global vmap space is protected by a single spinlock. Such approach > > > has a clear bottleneck if many CPUs simultaneously access to one resource. > > > > > > In this talk i would like to describe a drawback, show some data related > > > to contentions and places where those occur in a code. Apart of that i > > > would like to share ideas how to eliminate it providing a few approaches > > > and compare them. > > > > It's been some time since you brough this up. Has there been any > > progress on the topic? Do you still find it important to discuss it at > > LSFMM? > > > The idea about sequence was/is: > > 1) Give an overview on the proposal; > 2) Submit patches to address the problem; > 3) Start a discussion over lkml with people who are interested in it; > 4) Send out a complete solution. Thanks for the clarification. The usual LSFMM format is strongly discussion focused. Long presentations are usually discouraged and they should only introduce people to the underlying problem to kick of a discussion. That being said, IMO it would be helpful to have some material on the mailing list before any discussion could be productive. Thanks! -- Michal Hocko SUSE Labs