Re: process creation time increases linearly with shmem

From: Ross Biro <ross.biro@gmail.com>
To: Rik van Riel <riel@redhat.com>
Cc: Ray Fucillo <fucillo@intersystems.com>,
	Nick Piggin <nickpiggin@yahoo.com.au>,
	Hugh Dickins <hugh@veritas.com>,
	Linus Torvalds <torvalds@osdl.org>,
	linux-kernel@vger.kernel.org
Subject: Re: process creation time increases linearly with shmem
Date: Fri, 26 Aug 2005 11:20:37 -0700	[thread overview]
Message-ID: <8783be6605082611206dce314e@mail.gmail.com> (raw)
In-Reply-To: <Pine.LNX.4.63.0508261349550.25015@cuia.boston.redhat.com>

On 8/26/05, Rik van Riel <riel@redhat.com> wrote:
> 
> Filling in all the page table entries at the first fault to
> a VMA doesn't make much sense, IMHO.
> 
> 
> I suspect we would be better off without that extra complexity,
> unless there is a demonstrated benefit to it.

You are probably right, but do you want to put in a patch that might
have a big performance impact in either direction with out verifying
it?

My suggestion is safe, but most likely sub-optimal.  What everyone
else is suggesting may be far better, but needs to be verified first.

I'm suggesting that we change the code to do the same work fork would
have done on the first page fault immediately, since it's easy to
argue that it's not much worse than we have now and much better in
many cases, and then try to experiment and figure out  what the
correct solution is.

    Ross