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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 1F4B6C07E95 for ; Fri, 2 Jul 2021 18:29:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF19F613F1 for ; Fri, 2 Jul 2021 18:29:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230174AbhGBScU (ORCPT ); Fri, 2 Jul 2021 14:32:20 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:48010 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230114AbhGBScT (ORCPT ); Fri, 2 Jul 2021 14:32:19 -0400 Date: Fri, 2 Jul 2021 20:29:44 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1625250586; h=from:from:reply-to:subject:subject: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=1LP04KpdM/Xii9XazRoYT55qF7Zs2WWSaf0X5rgB/YI=; b=OWg8L2E+Rd3pYI642Oye8e4r4BiJocV794SpGvwipz4GoE4GhuCuDzsOixQ7CJ6BV3ZDs2 bpu/1AO6xtEgGmdT9iv7fnormWD61hMjlk30r3DhwkdHB8ezKkfZKKsSsHhnAJuYvI+j/E ow/w0VmGaj2ao3TBK6EFLtjmcuQ6saJTMRm48PwFU/9NQOZXqSH0VX+xJLGd7+jTZz3kkW KHAWzlvOk/O0bFqUEONCZLYJ0ezlBKrAldqmxo7uXVHnEDz0Yh5IvPUYSN+VyIght8Skwu FvNhMxmfDuGbj1pP8iyfeSXg/ru8n00gwkzFmAO7u95FPla17KJzjNoRjhF5aA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1625250586; h=from:from:reply-to:subject:subject: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=1LP04KpdM/Xii9XazRoYT55qF7Zs2WWSaf0X5rgB/YI=; b=6lw7AkFPWzvD6KtRY6f6Uwn1CU3N72ZwVjan69VBAARy2e3VZTII4arXD/qZXbGBUm9J6x 2tHMV49sbM05F1Bg== From: Sebastian Andrzej Siewior To: Vlastimil Babka Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Peter Zijlstra , Jann Horn Subject: Re: [RFC v2 00/34] SLUB: reduce irq disabled scope and make it RT compatible Message-ID: <20210702182944.lqa7o2a25to6czju@linutronix.de> References: <20210609113903.1421-1-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210609113903.1421-1-vbabka@suse.cz> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I replaced my slub changes with slub-local-lock-v2r3. I haven't seen any complains from lockdep or so which is good. Then I did this with RT enabled (and no debug): - A "time make -j32" run of allmodconfig on /dev/shm. Old: | real 20m6,217s | user 568m22,553s | sys 48m33,126s New: | real 20m9,049s | user 569m32,096s | sys 48m47,670s These 3 seconds here are probably in the noise range. - perf_5.10 stat -r 10 hackbench -g200 -s 4096 -l500 Old: | 464.967,20 msec task-clock # 27,220 CPUs utilized ( +- 0,16% ) | 7.683.944 context-switches # 0,017 M/sec ( +- 0,86% ) | 931.380 cpu-migrations # 0,002 M/sec ( +- 4,94% ) | 219.569 page-faults # 0,472 K/sec ( +- 0,39% ) | 1.104.727.599.918 cycles # 2,376 GHz ( +- 0,18% ) | 941.428.898.087 stalled-cycles-frontend # 85,22% frontend cycles idle ( +- 0,24% ) | 729.016.546.572 stalled-cycles-backend # 65,99% backend cycles idle ( +- 0,32% ) | 340.133.571.519 instructions # 0,31 insn per cycle | # 2,77 stalled cycles per insn ( +- 0,12% ) | 73.746.821.314 branches # 158,607 M/sec ( +- 0,13% ) | 377.838.006 branch-misses # 0,51% of all branches ( +- 1,01% ) | | 17,0820 +- 0,0202 seconds time elapsed ( +- 0,12% ) New: | 422.865,71 msec task-clock # 4,782 CPUs utilized ( +- 0,34% ) | 14.594.238 context-switches # 0,035 M/sec ( +- 0,43% ) | 3.737.926 cpu-migrations # 0,009 M/sec ( +- 0,46% ) | 218.474 page-faults # 0,517 K/sec ( +- 0,74% ) | 940.715.812.020 cycles # 2,225 GHz ( +- 0,34% ) | 716.593.827.820 stalled-cycles-frontend # 76,18% frontend cycles idle ( +- 0,39% ) | 550.730.862.839 stalled-cycles-backend # 58,54% backend cycles idle ( +- 0,43% ) | 417.274.588.907 instructions # 0,44 insn per cycle | # 1,72 stalled cycles per insn ( +- 0,17% ) | 92.814.150.290 branches # 219,488 M/sec ( +- 0,17% ) | 822.102.170 branch-misses # 0,89% of all branches ( +- 0,41% ) | | 88,427 +- 0,618 seconds time elapsed ( +- 0,70% ) So this is outside of the noise range. I'm not sure where this is coming from. My guess would be higher lock contention within the memory allocator. > The remaining patches to upstream from the RT tree are small ones related to > KConfig. The patch that restricts PREEMPT_RT to SLUB (not SLAB or SLOB) makes > sense. The patch that disables CONFIG_SLUB_CPU_PARTIAL with PREEMPT_RT could > perhaps be re-evaluated as the series also addresses some latency issues with > percpu partial slabs. With that series the PARTIAL slab can be indeed enabled. I have (had) a half done series where I had PARTIAL enabled and noticed a slight increase in latency so made it "default y on !RT". It wasn't dramatic but appeared to be outside of noise. Sebastian