From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
To: Nitesh Narayan Lal <nitesh@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>,
kvm@vger.kernel.org, david@redhat.com, dave.hansen@intel.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
akpm@linux-foundation.org, yang.zhang.wz@gmail.com,
pagupta@redhat.com, riel@surriel.com, konrad.wilk@oracle.com,
lcapitulino@redhat.com, wei.w.wang@intel.com,
aarcange@redhat.com, pbonzini@redhat.com,
dan.j.williams@intel.com
Subject: Re: [PATCH v2 QEMU] virtio-balloon: Provide a interface for "bubble hinting"
Date: Thu, 25 Jul 2019 13:00:07 -0700 [thread overview]
Message-ID: <6bee80b95885e74a5e46e3bd3e708d092b4a666f.camel@linux.intel.com> (raw)
In-Reply-To: <cc98f7c9-bcf8-79cb-54b7-de7c996f76e1@redhat.com>
On Thu, 2019-07-25 at 14:25 -0400, Nitesh Narayan Lal wrote:
> On 7/25/19 12:16 PM, Alexander Duyck wrote:
> > On Thu, 2019-07-25 at 11:16 -0400, Michael S. Tsirkin wrote:
> > > On Thu, Jul 25, 2019 at 08:05:30AM -0700, Alexander Duyck wrote:
> > > > On Thu, 2019-07-25 at 07:35 -0400, Nitesh Narayan Lal wrote:
> > > > > On 7/24/19 6:03 PM, Alexander Duyck wrote:
> > > > > > On Wed, 2019-07-24 at 17:38 -0400, Michael S. Tsirkin wrote:
> > > > > > > On Wed, Jul 24, 2019 at 10:12:10AM -0700, Alexander Duyck wrote:
> > > > > > > > From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> > > > > > > >
> > > > > > >
<snip>
> > Ideally we should be able
> > to provide the hints and have them feed whatever is supposed to be using
> > them. So for example I could probably look at also clearing the bitmaps
> > when migration is in process.
> >
> > Also, I am wonder if the free page hints would be redundant with the form
> > of page hinting/reporting that I have since we should be migrating a much
> > smaller footprint anyway if the pages have been madvised away before we
> > even start the migration.
> >
> > > FWIW Nitesh's RFC does not have this limitation.
> > Yes, but there are also limitations to his approach. For example the fact
> > that the bitmap it maintains is back to being a hint rather then being
> > very exact.
>
> True.
>
>
> > As a result you could end up walking the bitmap for a while
> > clearing bits without ever finding a free page.
>
> Are referring to the overhead which will be introduced due to bitmap scanning on
> very large guests?
Yes. One concern I have had is that for large memory footprints the RFC
would end up having a large number of false positives on an highly active
system. I am worried it will result in a feedback loop where having more
false hits slows down your processing speed, and the slower your
processing speed the more likely you are to encounter more false hits.
next prev parent reply other threads:[~2019-07-25 20:00 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-24 16:54 [PATCH v2 0/5] mm / virtio: Provide support for page hinting Alexander Duyck
2019-07-24 16:56 ` [PATCH v2 1/5] mm: Adjust shuffle code to allow for future coalescing Alexander Duyck
2019-07-24 16:58 ` [PATCH v2 2/5] mm: Move set/get_pcppage_migratetype to mmzone.h Alexander Duyck
2019-07-24 17:00 ` [PATCH v2 3/5] mm: Use zone and order instead of free area in free_list manipulators Alexander Duyck
2019-07-24 17:03 ` [PATCH v2 4/5] mm: Introduce Hinted pages Alexander Duyck
2019-07-25 8:53 ` David Hildenbrand
2019-07-25 11:46 ` Nitesh Narayan Lal
2019-07-25 11:54 ` David Hildenbrand
2019-07-25 15:59 ` Alexander Duyck
2019-07-25 16:48 ` David Hildenbrand
2019-07-25 17:38 ` Alexander Duyck
2019-07-25 18:32 ` David Hildenbrand
2019-07-25 20:37 ` Alexander Duyck
2019-07-25 20:44 ` David Hildenbrand
2019-07-26 12:24 ` Nitesh Narayan Lal
2019-07-26 16:38 ` Alexander Duyck
2019-07-24 17:05 ` [PATCH v2 5/5] virtio-balloon: Add support for providing page hints to host Alexander Duyck
2019-07-24 19:02 ` Michael S. Tsirkin
2019-07-24 19:07 ` Nitesh Narayan Lal
2019-07-24 19:26 ` Michael S. Tsirkin
2019-07-24 20:37 ` Alexander Duyck
2019-07-24 20:43 ` Michael S. Tsirkin
2019-07-25 14:44 ` Nitesh Narayan Lal
2019-07-25 14:54 ` Michael S. Tsirkin
2019-07-25 14:56 ` Alexander Duyck
2019-07-25 14:59 ` Michael S. Tsirkin
2019-07-25 17:42 ` Nitesh Narayan Lal
2019-07-25 19:54 ` Alexander Duyck
2019-07-24 17:12 ` [PATCH v2 QEMU] virtio-balloon: Provide a interface for "bubble hinting" Alexander Duyck
2019-07-24 19:02 ` Michael S. Tsirkin
2019-07-24 20:18 ` Alexander Duyck
2019-07-24 20:29 ` Nitesh Narayan Lal
2019-07-24 20:42 ` Michael S. Tsirkin
2019-07-29 16:58 ` Alexander Duyck
2019-07-29 19:25 ` Michael S. Tsirkin
2019-07-29 20:21 ` Alexander Duyck
2019-07-29 20:49 ` Michael S. Tsirkin
2019-07-29 21:37 ` Alexander Duyck
2019-07-29 22:11 ` Michael S. Tsirkin
2019-07-24 20:46 ` Michael S. Tsirkin
2019-07-24 21:14 ` Alexander Duyck
2019-07-25 11:57 ` Nitesh Narayan Lal
2019-07-25 14:57 ` Alexander Duyck
2019-07-24 21:38 ` Michael S. Tsirkin
2019-07-24 22:03 ` Alexander Duyck
2019-07-24 22:08 ` Michael S. Tsirkin
2019-07-24 22:27 ` Alexander Duyck
2019-07-25 6:07 ` Michael S. Tsirkin
2019-07-25 11:35 ` Nitesh Narayan Lal
2019-07-25 15:05 ` Alexander Duyck
2019-07-25 15:16 ` Michael S. Tsirkin
2019-07-25 16:16 ` Alexander Duyck
2019-07-25 17:19 ` Michael S. Tsirkin
2019-07-25 18:25 ` Nitesh Narayan Lal
2019-07-25 20:00 ` Alexander Duyck [this message]
2019-07-25 20:14 ` Nitesh Narayan Lal
2019-07-24 18:40 ` [PATCH v2 0/5] mm / virtio: Provide support for page hinting Nitesh Narayan Lal
2019-07-24 18:41 ` David Hildenbrand
2019-07-24 19:31 ` Michael S. Tsirkin
2019-07-24 19:47 ` David Hildenbrand
2019-07-24 19:54 ` Nitesh Narayan Lal
2019-07-24 21:32 ` Michael S. Tsirkin
2019-07-24 19:24 ` Michael S. Tsirkin
2019-07-24 20:27 ` Alexander Duyck
2019-07-24 20:38 ` Nitesh Narayan Lal
2019-07-24 21:00 ` Alexander Duyck
2019-07-25 12:08 ` Nitesh Narayan Lal
2019-07-24 20:38 ` Michael S. Tsirkin
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