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From: Andrea Arcangeli <aarcange@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Avi Kivity <avi@redhat.com>, KVM list <kvm@vger.kernel.org>
Subject: Re: unit tests and get_user_pages_ptes_fast()
Date: Tue, 5 Oct 2010 16:15:47 +0200	[thread overview]
Message-ID: <20101005141547.GV26357@random.random> (raw)
In-Reply-To: <20101005092217.GA15663@amt.cnet>

On Tue, Oct 05, 2010 at 06:22:17AM -0300, Marcelo Tosatti wrote:
> It'll not be so advantageous for ksm because there should be read-faults
> very rarely on that case.

It'll also make all clean swapcache dirty for no good.

> Will post.

If we've to walk pagetables twice, why don't you do this:

writable=1
get_user_pages_fast(write=write_fault)
if (!write_fault)
   writable = __get_user_pages_fast(write=1)

That will solve the debugging knob and it'll solve ksm and it'll be
optimal for read swapins on exclusive clean swapcache too.

  reply	other threads:[~2010-10-05 14:15 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-10-04  9:35 unit tests and get_user_pages_ptes_fast() Avi Kivity
2010-10-04 13:40 ` Andrea Arcangeli
2010-10-04 23:59   ` Marcelo Tosatti
2010-10-05  7:36     ` Avi Kivity
2010-10-05  9:22       ` Marcelo Tosatti
2010-10-05 14:15         ` Andrea Arcangeli [this message]
2010-10-05 14:25           ` Avi Kivity
2010-10-05 14:32             ` Andrea Arcangeli
2010-10-05 14:36               ` Avi Kivity

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