Re: [PATCH] sysctl: Add a feature to drop caches selectively

From: Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>
To: dedekind1@gmail.com, Dave Chinner <david@fromorbit.com>
Cc: Thomas Knauth <thomas.knauth@gmx.de>,
	David Rientjes <rientjes@google.com>,
	Maksym Planeta <mcsim.planeta@gmail.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sysctl: Add a feature to drop caches selectively
Date: Thu, 26 Jun 2014 12:36:52 +0200	[thread overview]
Message-ID: <53ABF7C4.1000906@itwm.fraunhofer.de> (raw)
In-Reply-To: <1403763199.20275.39.camel@sauron.fi.intel.com>

On 06/26/2014 08:13 AM, Artem Bityutskiy wrote:
> On Thu, 2014-06-26 at 11:06 +1000, Dave Chinner wrote:
>> Your particular use case can be handled by directing your benchmark
>> at a filesystem mount point and unmounting the filesystem in between
>> benchmark runs. There is no ned to adding kernel functionality for
>> somethign that can be so easily acheived by other means, especially
>> in benchmark environments where *everything* is tightly controlled.
>
> If I was a benchmark writer, I would not be willing running it as root
> to be able to mount/unmount, I would not be willing to require the
> customer creating special dedicated partitions for the benchmark,
> because this is too user-unfriendly. Or do I make incorrect assumptions?

But why a sysctl then? And also don't see a point for that at all, why 
can't the benchmark use posix_fadvise(POSIX_FADV_DONTNEED)?

Cheers,
Bernd