From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <owner-linux-mm@kvack.org>
Received: from mail-it0-f72.google.com (mail-it0-f72.google.com [209.85.214.72])
	by kanga.kvack.org (Postfix) with ESMTP id F300C6B02B4
	for <linux-mm@kvack.org>; Thu, 29 Jun 2017 13:05:57 -0400 (EDT)
Received: by mail-it0-f72.google.com with SMTP id i71so14324082itf.2
        for <linux-mm@kvack.org>; Thu, 29 Jun 2017 10:05:57 -0700 (PDT)
Received: from resqmta-ch2-03v.sys.comcast.net (resqmta-ch2-03v.sys.comcast.net. [2001:558:fe21:29:69:252:207:35])
        by mx.google.com with ESMTPS id p12si2140239ioo.242.2017.06.29.10.05.56
        for <linux-mm@kvack.org>
        (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
        Thu, 29 Jun 2017 10:05:57 -0700 (PDT)
Date: Thu, 29 Jun 2017 12:05:50 -0500 (CDT)
From: Christoph Lameter <cl@linux.com>
Subject: Re: [PATCH v2] mm: Add SLUB free list pointer obfuscation
In-Reply-To: <CAGXu5jJEi_CS-CB=-4369TFRyeN4oQdmGS+HV-zoi4rSPpq3Jw@mail.gmail.com>
Message-ID: <alpine.DEB.2.20.1706291204460.17478@east.gentwo.org>
References: <20170623015010.GA137429@beast> <CAGXu5jJEi_CS-CB=-4369TFRyeN4oQdmGS+HV-zoi4rSPpq3Jw@mail.gmail.com>
Content-Type: text/plain; charset=US-ASCII
Sender: owner-linux-mm@kvack.org
List-ID: <linux-mm.kvack.org>
To: Kees Cook <keescook@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>, Laura Abbott <labbott@redhat.com>, Daniel Micay <danielmicay@gmail.com>, Pekka Enberg <penberg@kernel.org>, David Rientjes <rientjes@google.com>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Ingo Molnar <mingo@kernel.org>, Josh Triplett <josh@joshtriplett.org>, Andy Lutomirski <luto@kernel.org>, Nicolas Pitre <nicolas.pitre@linaro.org>, Tejun Heo <tj@kernel.org>, Daniel Mack <daniel@zonque.org>, Sebastian Andrzej Siewior <bigeasy@linutronix.de>, Sergey Senozhatsky <sergey.senozhatsky@gmail.com>, Helge Deller <deller@gmx.de>, Rik van Riel <riel@redhat.com>, LKML <linux-kernel@vger.kernel.org>, Linux-MM <linux-mm@kvack.org>, "kernel-hardening@lists.openwall.com" <kernel-hardening@lists.openwall.com>

On Sun, 25 Jun 2017, Kees Cook wrote:

> The difference gets lost in the noise, but if the above is sensible,
> it's 0.07% slower. ;)

Hmmm... These differences add up. Also in a repetative benchmark like that
you do not see the impact that the additional cacheline use in the cpu
cache has on larger workloads. Those may be pushed over the edge of l1 or
l2 capacity at some point which then causes drastic regressions.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>