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Date: Tue, 15 Nov 2011 11:29:27 -0500
From: Rik van Riel <riel@redhat.com>
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To: Dan Magenheimer <dan.magenheimer@oracle.com>
CC: Andrea Arcangeli <aarcange@redhat.com>, Pekka Enberg <penberg@kernel.org>,
        Cyclonus J <cyclonusj@gmail.com>,
        Sasha Levin <levinsasha928@gmail.com>,
        Christoph Hellwig <hch@infradead.org>,
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        Linus Torvalds <torvalds@linux-foundation.org>, linux-mm@kvack.org,
        LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Konrad Wilk <konrad.wilk@oracle.com>,
        Jeremy Fitzhardinge <jeremy@goop.org>,
        Seth Jennings <sjenning@linux.vnet.ibm.com>, ngupta@vflare.org,
        Chris Mason <chris.mason@oracle.com>, JBeulich@novell.com,
        Dave Hansen <dave@linux.vnet.ibm.com>,
        Jonathan Corbet <corbet@lwn.net>
Subject: Re: [GIT PULL] mm: frontswap (for 3.2 window)
References: <b2fa75b6-f49c-4399-ba94-7ddf08d8db6e@default> <75efb251-7a5e-4aca-91e2-f85627090363@default> <20111027215243.GA31644@infradead.org> <1319785956.3235.7.camel@lappy> <CAOzbF4fnD=CGR-nizZoBxmFSuAjFC3uAHf3wDj5RLneJvJhrOQ@mail.gmail.comCAOJsxLGOTw7rtFnqeHvzFxifA0QgPVDHZzrEo=-uB2Gkrvp=JQ@mail.gmail.com> <552d2067-474d-4aef-a9a4-89e5fd8ef84f@default20111031181651.GF3466@redhat.com> <60592afd-97aa-4eaf-b86b-f6695d31c7f1@default> <20111031223717.GI3466@redhat.com> <1b2e4f74-7058-4712-85a7-84198723e3ee@default 4EB1AD53.2000600@redhat.com> <cb397723-5297-493d-9bbd-522a6400a5a6@default>
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On 11/02/2011 05:14 PM, Dan Magenheimer wrote:

> It occurs to me that batching could be done locally without
> changing the in-kernel "API" (i.e. frontswap_ops)... the
> guest-side KVM tmem-backend-driver could do the compression
> into guest-side memory and make a single
> hypercall=vmexit/vmenter whenever it has collected enough for
> a batch.

That seems like the best way to do it, indeed.

Do the current hooks allow that mode of operation,
or do the hooks only return after the entire operation
has completed?