From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=SV65=O7=kvack.org=owner-linux-mm@kernel.org>
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 98520C433EF
	for <linux-mm@archiver.kernel.org>; Mon, 11 Oct 2021 07:20:40 +0000 (UTC)
Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17])
	by mail.kernel.org (Postfix) with ESMTP id 5BF2260C4A
	for <linux-mm@archiver.kernel.org>; Mon, 11 Oct 2021 07:20:40 +0000 (UTC)
DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 5BF2260C4A
Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gentwo.de
Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org
Received: by kanga.kvack.org (Postfix)
	id 015DB6B0071; Mon, 11 Oct 2021 03:20:40 -0400 (EDT)
Received: by kanga.kvack.org (Postfix, from userid 40)
	id EE1526B0072; Mon, 11 Oct 2021 03:20:39 -0400 (EDT)
X-Delivered-To: int-list-linux-mm@kvack.org
Received: by kanga.kvack.org (Postfix, from userid 63042)
	id DA9B7900002; Mon, 11 Oct 2021 03:20:39 -0400 (EDT)
X-Delivered-To: linux-mm@kvack.org
Received: from forelay.hostedemail.com (smtprelay0091.hostedemail.com [216.40.44.91])
	by kanga.kvack.org (Postfix) with ESMTP id CABC06B0071
	for <linux-mm@kvack.org>; Mon, 11 Oct 2021 03:20:39 -0400 (EDT)
Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251])
	by forelay02.hostedemail.com (Postfix) with ESMTP id F37F92FD99
	for <linux-mm@kvack.org>; Mon, 11 Oct 2021 07:20:37 +0000 (UTC)
X-FDA: 78683308914.25.49F2B47
Received: from gentwo.de (vmi485042.contaboserver.net [161.97.139.209])
	by imf15.hostedemail.com (Postfix) with ESMTP id 91095D001F3A
	for <linux-mm@kvack.org>; Mon, 11 Oct 2021 07:20:37 +0000 (UTC)
Received: by gentwo.de (Postfix, from userid 1001)
	id 44B44B00691; Mon, 11 Oct 2021 09:20:36 +0200 (CEST)
Received: from localhost (localhost [127.0.0.1])
	by gentwo.de (Postfix) with ESMTP id 42397B0025F;
	Mon, 11 Oct 2021 09:20:36 +0200 (CEST)
Date: Mon, 11 Oct 2021 09:20:36 +0200 (CEST)
From: Christoph Lameter <cl@gentwo.de>
To: Hyeonggon Yoo <42.hyeyoo@gmail.com>
cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, 
    Pekka Enberg <penberg@kernel.org>, David Rientjes <rientjes@google.com>, 
    Joonsoo Kim <iamjoonsoo.kim@lge.com>, 
    Andrew Morton <akpm@linux-foundation.org>, 
    Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH] mm, slub: Use prefetchw instead of prefetch
In-Reply-To: <20211008133602.4963-1-42.hyeyoo@gmail.com>
Message-ID: <alpine.DEB.2.22.394.2110110919050.130815@gentwo.de>
References: <20211008133602.4963-1-42.hyeyoo@gmail.com>
User-Agent: Alpine 2.22 (DEB 394 2020-01-19)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
X-Rspamd-Server: rspam01
X-Rspamd-Queue-Id: 91095D001F3A
X-Stat-Signature: 8poefz3kbitekwgwh96sp3kbhynhrpee
Authentication-Results: imf15.hostedemail.com;
	dkim=none;
	dmarc=none;
	spf=pass (imf15.hostedemail.com: domain of cl@gentwo.de designates 161.97.139.209 as permitted sender) smtp.mailfrom=cl@gentwo.de
X-HE-Tag: 1633936837-464655
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: <linux-mm.kvack.org>

On Fri, 8 Oct 2021, Hyeonggon Yoo wrote:

> It's certain that an object will be not only read, but also
> written after allocation.

get_freepointer is used in multiple code path not only in allocation. It
is for example used when scanning through a freelist.

With this change all objects get needlessly dirtied and the cross cpu
cache contention is increased.