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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 60E62EE49A8 for ; Tue, 22 Aug 2023 09:51:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234510AbjHVJv7 (ORCPT ); Tue, 22 Aug 2023 05:51:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33156 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232971AbjHVJv6 (ORCPT ); Tue, 22 Aug 2023 05:51:58 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7FD171A1 for ; Tue, 22 Aug 2023 02:51:56 -0700 (PDT) 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-out1.suse.de (Postfix) with ESMTPS id 31F7F22C47; Tue, 22 Aug 2023 09:51:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1692697915; 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=KdCgYWOgTsCE9k8ZFgfn4CkkXIjrshXgCbrrriZQv2s=; b=zmjOqbPm4+CA5+kFgDuCVrsguxPDcRrBtAl8FpIExJ/x05ZfmzSQZTPrTlP788a4nUmgnJ dhXTGu3bTzO1Yi4UPEQd6WmU8gJZ+GD4w8E9guj2Vn7Bv2JKjZvrj4uwW9n6lXC/7T+ShY nttzTPSLb6YyHIQvit4/VagiJxvXEBM= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1692697915; 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=KdCgYWOgTsCE9k8ZFgfn4CkkXIjrshXgCbrrriZQv2s=; b=r4btaUS+/3tCM7grMQ9BA+6fvA3h9G9aDSvHfszRfTRNnqZYg2thwi+Y0LudtLtPMLy5Ol HOnqQi92nuNlpBCw== 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 22DBA13919; Tue, 22 Aug 2023 09:51:55 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 0zBzCDuF5GTGEgAAMHmgww (envelope-from ); Tue, 22 Aug 2023 09:51:55 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id A32F6A0774; Tue, 22 Aug 2023 11:51:54 +0200 (CEST) Date: Tue, 22 Aug 2023 11:51:54 +0200 From: Jan Kara To: Mateusz Guzik Cc: Dennis Zhou , linux-kernel@vger.kernel.org, tj@kernel.org, cl@linux.com, akpm@linux-foundation.org, shakeelb@google.com, linux-mm@kvack.org, jack@suse.cz Subject: Re: [PATCH 0/2] execve scalability issues, part 1 Message-ID: <20230822095154.7cr5ofogw552z3jk@quack3> References: <20230821202829.2163744-1-mjguzik@gmail.com> <20230821213951.bx3yyqh7omdvpyae@f> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 22-08-23 00:29:49, Mateusz Guzik wrote: > On 8/21/23, Mateusz Guzik wrote: > > True Fix(tm) is a longer story. > > > > Maybe let's sort out this patchset first, whichever way. :) > > > > So I found the discussion around the original patch with a perf > regression report. > > https://lore.kernel.org/linux-mm/20230608111408.s2minsenlcjow7q3@quack3/ > > The reporter suggests dodging the problem by only allocating per-cpu > counters when the process is going multithreaded. Given that there is > still plenty of forever single-threaded procs out there I think that's > does sound like a great plan regardless of what happens with this > patchset. > > Almost all access is already done using dedicated routines, so this > should be an afternoon churn to sort out, unless I missed a > showstopper. (maybe there is no good place to stuff a flag/whatever > other indicator about the state of counters?) > > That said I'll look into it some time this or next week. Good, just let me know how it went, I also wanted to start looking into this to come up with some concrete patches :). What I had in mind was that we could use 'counters == NULL' as an indication that the counter is still in 'single counter mode'. Honza -- Jan Kara SUSE Labs, CR