linux-kernel - Re: [PATCH 4/4] add ksm kernel shared memory driver.

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Date:	Wed, 1 Apr 2009 18:22:15 -0700
From:	Chris Wright <chrisw@...hat.com>
To:	Anthony Liguori <anthony@...emonkey.ws>
Cc:	Andrea Arcangeli <aarcange@...hat.com>,
	Izik Eidus <ieidus@...hat.com>, linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org, linux-mm@...ck.org, avi@...hat.com,
	chrisw@...hat.com, riel@...hat.com, jeremy@...p.org,
	mtosatti@...hat.com, hugh@...itas.com, corbet@....net,
	yaniv@...hat.com, dmonakhov@...nvz.org
Subject: Re: [PATCH 4/4] add ksm kernel shared memory driver.

* Anthony Liguori (anthony@...emonkey.ws) wrote:
> The ioctl() interface is quite bad for what you're doing.  You're  
> telling the kernel extra information about a VA range in userspace.   
> That's what madvise is for.  You're tweaking simple read/write values of  
> kernel infrastructure.  That's what sysfs is for.

I agree re: sysfs (brought it up myself before).  As far as madvise vs.
ioctl, the one thing that comes from the ioctl is fops->release to
automagically unregister memory on exit.  This needs to be handled
anyway if some -p pid is added to add a process after it's running,
so less weight there.

thanks,
-chris
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