linux-kernel - Re: [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges

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Message-ID: <Pine.LNX.4.64.0802281658560.1954@schroedinger.engr.sgi.com>
Date:	Thu, 28 Feb 2008 16:59:59 -0800 (PST)
From:	Christoph Lameter <clameter@....com>
To:	Andrea Arcangeli <andrea@...ranet.com>
cc:	Nick Piggin <nickpiggin@...oo.com.au>, akpm@...ux-foundation.org,
	Robin Holt <holt@....com>, Avi Kivity <avi@...ranet.com>,
	Izik Eidus <izike@...ranet.com>,
	kvm-devel@...ts.sourceforge.net,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	general@...ts.openfabrics.org,
	Steve Wise <swise@...ngridcomputing.com>,
	Roland Dreier <rdreier@...co.com>,
	Kanoj Sarcar <kanojsarcar@...oo.com>, steiner@....com,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	daniel.blueman@...drics.com
Subject: Re: [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges

On Fri, 29 Feb 2008, Andrea Arcangeli wrote:

> On Thu, Feb 28, 2008 at 10:43:54AM -0800, Christoph Lameter wrote:
> > What about invalidate_page()?
> 
> That would just spin waiting an ack (just like the smp-tlb-flushing
> invalidates in numa already does).

And thus the device driver may stop receiving data on a UP system? It will 
never get the ack.
 
> Thinking more about this, we could also parallelize it with an
> invalidate_page_before/end. If it takes 1usec to flush remotely,
> scheduling would be overkill, but spending 1usec in a while loop isn't
> nice if we can parallelize that 1usec with the ipi-tlb-flush. Not sure
> if it makes sense... it certainly would be quick to add it (especially
> thanks to _notify ;).

invalidate_page_before/end could be realized as an 
invalidate_range_begin/end on a page sized range?
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