From: Rik van Riel <riel@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Rafael Aquini <aquini@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Rusty Russell <rusty@rustcorp.com.au>, Mel Gorman <mel@csn.ul.ie>,
Andi Kleen <andi@firstfloor.org>,
Andrew Morton <akpm@linux-foundation.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Minchan Kim <minchan@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: [PATCH v9 0/5] make balloon pages movable by compaction
Date: Sun, 26 Aug 2012 10:40:37 -0400 [thread overview]
Message-ID: <503A3565.2060004@redhat.com> (raw)
In-Reply-To: <20120826075840.GE19551@redhat.com>
On 08/26/2012 03:58 AM, Michael S. Tsirkin wrote:
> On Sat, Aug 25, 2012 at 02:24:55AM -0300, Rafael Aquini wrote:
>> Memory fragmentation introduced by ballooning might reduce significantly
>> the number of 2MB contiguous memory blocks that can be used within a guest,
>> thus imposing performance penalties associated with the reduced number of
>> transparent huge pages that could be used by the guest workload.
>>
>> This patch-set follows the main idea discussed at 2012 LSFMMS session:
>> "Ballooning for transparent huge pages" -- http://lwn.net/Articles/490114/
>> to introduce the required changes to the virtio_balloon driver, as well as
>> the changes to the core compaction & migration bits, in order to make those
>> subsystems aware of ballooned pages and allow memory balloon pages become
>> movable within a guest, thus avoiding the aforementioned fragmentation issue
>
> Meta-question: are there any numbers showing gain from this patchset?
>
> The reason I ask, on migration we notify host about each page
> individually. If this is rare maybe the patchset does not help much.
> If this is common we would be better off building up a list of multiple
> pages and passing them in one go.
The gain is in getting a better THP allocation rate inside the
guest, allowing applications to run faster.
The rarer it is for this code to run, the better - it means we
are getting the benefits without the overhead :)
--
All rights reversed
next prev parent reply other threads:[~2012-08-26 14:41 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-25 5:24 [PATCH v9 0/5] make balloon pages movable by compaction Rafael Aquini
2012-08-25 5:24 ` [PATCH v9 1/5] mm: introduce a common interface for balloon pages mobility Rafael Aquini
2012-08-26 7:55 ` Michael S. Tsirkin
2012-08-27 20:28 ` Rafael Aquini
2012-08-28 15:23 ` Michael S. Tsirkin
2012-08-25 5:24 ` [PATCH v9 2/5] mm: introduce compaction and migration for ballooned pages Rafael Aquini
2012-08-25 5:24 ` [PATCH v9 3/5] virtio_balloon: introduce migration primitives to balloon pages Rafael Aquini
2012-08-26 7:42 ` Michael S. Tsirkin
2012-08-27 19:47 ` Rafael Aquini
2012-08-28 15:54 ` Michael S. Tsirkin
2012-08-28 17:37 ` Rafael Aquini
2012-08-28 17:57 ` Michael S. Tsirkin
2012-08-28 18:05 ` Rafael Aquini
2012-08-25 5:24 ` [PATCH v9 4/5] mm: introduce putback_movable_pages() Rafael Aquini
2012-08-25 5:25 ` [PATCH v9 5/5] mm: add vm event counters for balloon pages compaction Rafael Aquini
2012-08-26 7:58 ` [PATCH v9 0/5] make balloon pages movable by compaction Michael S. Tsirkin
2012-08-26 14:40 ` Rik van Riel [this message]
2012-08-26 15:44 ` Michael S. Tsirkin
2012-08-27 20:22 ` Rafael Aquini
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