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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EE01EC433F5 for ; Tue, 16 Nov 2021 02:14:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D702561B66 for ; Tue, 16 Nov 2021 02:14:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244107AbhKPCRI (ORCPT ); Mon, 15 Nov 2021 21:17:08 -0500 Received: from mail.kernel.org ([198.145.29.99]:55462 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238704AbhKORpr (ORCPT ); Mon, 15 Nov 2021 12:45:47 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id B1B3163315; Mon, 15 Nov 2021 17:29:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1636997371; bh=Q0f8il/c/FLJeu3lYaVf3gSiOpPrFL0RKxv/hu0szn8=; h=Date:From:To:Subject:From; b=eIJdOEQljgieervsKMkQXsQl9RWMSm6dg6GP9AurTWotX8nI1Y88QmISedoyTB5Y1 ebGvQpk2F97E80dwSfe5ZrziYtXKairi1ZFSSCqQ1TfA+i/BbS8W7YZ349j3tZ60qc YicjFpScMwKiWjpUE3/NMqN6s+2eUx9Fitf3/k9c= Date: Mon, 15 Nov 2021 09:29:30 -0800 From: akpm@linux-foundation.org To: bigeasy@linutronix.de, cl@linux.com, iamjoonsoo.kim@lge.com, mingo@kernel.org, mm-commits@vger.kernel.org, penberg@kernel.org, rientjes@google.com, tglx@linutronix.de, vbabka@suse.cz Subject: [merged] mm-allow-only-slub-on-preempt_rt.patch removed from -mm tree Message-ID: <20211115172930.54O4rMiRZ%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm: allow only SLUB on PREEMPT_RT has been removed from the -mm tree. Its filename was mm-allow-only-slub-on-preempt_rt.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Ingo Molnar Subject: mm: allow only SLUB on PREEMPT_RT Memory allocators may disable interrupts or preemption as part of the allocation and freeing process. For PREEMPT_RT it is important that these sections remain deterministic and short and therefore don't depend on the size of the memory to allocate/ free or the inner state of the algorithm. Until v3.12-RT the SLAB allocator was an option but involved several changes to meet all the requirements. The SLUB design fits better with PREEMPT_RT model and so the SLAB patches were dropped in the 3.12-RT patchset. Comparing the two allocator, SLUB outperformed SLAB in both throughput (time needed to allocate and free memory) and the maximal latency of the system measured with cyclictest during hackbench. SLOB was never evaluated since it was unlikely that it preforms better than SLAB. During a quick test, the kernel crashed with SLOB enabled during boot. Disable SLAB and SLOB on PREEMPT_RT. [bigeasy@linutronix.de: commit description] Link: https://lkml.kernel.org/r/20211015210336.gen3tib33ig5q2md@linutronix.de Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner Signed-off-by: Sebastian Andrzej Siewior Acked-by: Vlastimil Babka Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Signed-off-by: Andrew Morton --- init/Kconfig | 2 ++ 1 file changed, 2 insertions(+) --- a/init/Kconfig~mm-allow-only-slub-on-preempt_rt +++ a/init/Kconfig @@ -1896,6 +1896,7 @@ choice config SLAB bool "SLAB" + depends on !PREEMPT_RT select HAVE_HARDENED_USERCOPY_ALLOCATOR help The regular slab allocator that is established and known to work @@ -1916,6 +1917,7 @@ config SLUB config SLOB depends on EXPERT bool "SLOB (Simple Allocator)" + depends on !PREEMPT_RT help SLOB replaces the stock allocator with a drastically simpler allocator. SLOB is generally more space efficient but _ Patches currently in -mm which might be from mingo@kernel.org are