Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Mon, 11 Jan 2021 11:53:23 -0800
From:   =?iso-8859-1?Q?J=F6rn?= Engel <joern@purestorage.com>
To:     Marco Elver <elver@google.com>
Cc:     akpm@linux-foundation.org, glider@google.com, dvyukov@google.com,
        andreyknvl@google.com, jannh@google.com, mark.rutland@arm.com,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        kasan-dev@googlegroups.com
Subject: Re: [PATCH mm 1/2] kfence: add option to use KFENCE without static
 keys
Message-ID: <20210111195323.GA842777@cork>
References: <20210111091544.3287013-1-elver@google.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20210111091544.3287013-1-elver@google.com>
Precedence: bulk

On Mon, Jan 11, 2021 at 10:15:43AM +0100, Marco Elver wrote:
> For certain usecases, specifically where the sample interval is always
> set to a very low value such as 1ms, it can make sense to use a dynamic
> branch instead of static branches due to the overhead of toggling a
> static branch.

I ended up with 100µs and couldn't measure a performance problem in our
benchmarks.  My results don't have predictive value for anyone else, of
course.

> Therefore, add a new Kconfig option to remove the static branches and
> instead check kfence_allocation_gate if a KFENCE allocation should be
> set up.
> 
> Suggested-by: Jörn Engel <joern@purestorage.com>
> Signed-off-by: Marco Elver <elver@google.com>

Reviewed-by: Jörn Engel <joern@purestorage.com>

Jörn

--
One of the things I’ve discovered over the years, is that you can
create change or you can receive credit – not both.
-- Stephen Downes