From: "Wang, Wei W" <wei.w.wang@intel.com>
To: David Hildenbrand <david@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>
Cc: Nadav Amit <namit@vmware.com>,
Alexander Duyck <alexander.h.duyck@linux.intel.com>,
Tyler Sanderson <tysand@google.com>,
"virtualization@lists.linux-foundation.org"
<virtualization@lists.linux-foundation.org>,
David Rientjes <rientjes@google.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"Michal Hocko" <mhocko@kernel.org>
Subject: RE: Balloon pressuring page cache
Date: Wed, 5 Feb 2020 09:00:04 +0000 [thread overview]
Message-ID: <286AC319A985734F985F78AFA26841F73E41F367@shsmsx102.ccr.corp.intel.com> (raw)
In-Reply-To: <2b388a78-79cd-f99a-6f87-6446dcb4b819@redhat.com>
On Wednesday, February 5, 2020 4:57 PM, David Hildenbrand wrote:
> >> Yes, I agree with you. Yet, I am thinking about one
> >> (unlikely?impossible?) scenario. Can you refresh my brain why that
> >> cannot happen (IOW, why we don't have to wait for the host to process
> >> the request)?
> >>
> >> 1. Guest allocates a page and sends it to the host.
> >> 2. Shrinker gets active and releases that page again.
> >> 3. Some user in the guest allocates and modifies that page. After
> >> that, it is done using that page for the next hour.
> >> 4. The host processes the request and clears the bit in the dirty bitmap.
> >> 5. The guest is being migrated by the host. The modified page is not
> >> being migrated.
> >
> > Whenever the guest modifies a page during migration, it will be
> > captured by the dirty logging and the hypervisor will send the dirtied the
> page in the following round.
>
> Please explain why the steps I outlined don't apply esp. in the last round.
> Your general statement does not explain why this race can't happen.
>
The guest is stopped in the last round, thus no page will be modified at that time.
Best,
Wei
WARNING: multiple messages have this Message-ID (diff)
From: "Wang, Wei W" <wei.w.wang@intel.com>
To: David Hildenbrand <david@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>
Cc: "virtualization@lists.linux-foundation.org"
<virtualization@lists.linux-foundation.org>,
Tyler Sanderson <tysand@google.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Nadav Amit <namit@vmware.com>,
David Rientjes <rientjes@google.com>,
Alexander Duyck <alexander.h.duyck@linux.intel.com>,
Michal Hocko <mhocko@kernel.org>
Subject: RE: Balloon pressuring page cache
Date: Wed, 5 Feb 2020 09:00:04 +0000 [thread overview]
Message-ID: <286AC319A985734F985F78AFA26841F73E41F367@shsmsx102.ccr.corp.intel.com> (raw)
In-Reply-To: <2b388a78-79cd-f99a-6f87-6446dcb4b819@redhat.com>
On Wednesday, February 5, 2020 4:57 PM, David Hildenbrand wrote:
> >> Yes, I agree with you. Yet, I am thinking about one
> >> (unlikely?impossible?) scenario. Can you refresh my brain why that
> >> cannot happen (IOW, why we don't have to wait for the host to process
> >> the request)?
> >>
> >> 1. Guest allocates a page and sends it to the host.
> >> 2. Shrinker gets active and releases that page again.
> >> 3. Some user in the guest allocates and modifies that page. After
> >> that, it is done using that page for the next hour.
> >> 4. The host processes the request and clears the bit in the dirty bitmap.
> >> 5. The guest is being migrated by the host. The modified page is not
> >> being migrated.
> >
> > Whenever the guest modifies a page during migration, it will be
> > captured by the dirty logging and the hypervisor will send the dirtied the
> page in the following round.
>
> Please explain why the steps I outlined don't apply esp. in the last round.
> Your general statement does not explain why this race can't happen.
>
The guest is stopped in the last round, thus no page will be modified at that time.
Best,
Wei
next prev parent reply other threads:[~2020-02-05 9:00 UTC|newest]
Thread overview: 119+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-29 0:22 Balloon pressuring page cache Tyler Sanderson via Virtualization
2020-01-29 10:31 ` David Hildenbrand
2020-01-29 19:11 ` Tyler Sanderson via Virtualization
2020-01-30 15:02 ` David Hildenbrand
2020-01-30 15:02 ` David Hildenbrand
2020-01-30 15:20 ` Michael S. Tsirkin
2020-01-30 15:20 ` Michael S. Tsirkin
2020-01-30 15:23 ` David Hildenbrand
2020-01-30 15:23 ` David Hildenbrand
2020-01-30 15:31 ` Wang, Wei W
2020-01-30 15:31 ` Wang, Wei W
2020-01-30 19:59 ` Tyler Sanderson
2020-01-30 19:59 ` Tyler Sanderson via Virtualization
2020-02-03 13:11 ` Michael S. Tsirkin
2020-02-03 13:11 ` Michael S. Tsirkin
2020-02-03 16:18 ` Alexander Duyck
2020-02-03 16:34 ` David Hildenbrand
2020-02-03 16:34 ` David Hildenbrand
2020-02-03 17:03 ` Michael S. Tsirkin
2020-02-03 17:03 ` Michael S. Tsirkin
2020-02-03 20:32 ` Tyler Sanderson
2020-02-03 20:32 ` Tyler Sanderson via Virtualization
2020-02-03 21:22 ` Alexander Duyck
2020-02-03 23:16 ` Tyler Sanderson
2020-02-03 23:16 ` Tyler Sanderson via Virtualization
2020-02-04 0:10 ` Alexander Duyck
2020-02-04 5:45 ` Michael S. Tsirkin
2020-02-04 5:45 ` Michael S. Tsirkin
2020-02-04 8:29 ` David Hildenbrand
2020-02-04 8:29 ` David Hildenbrand
2020-02-04 18:52 ` Tyler Sanderson
2020-02-04 18:52 ` Tyler Sanderson via Virtualization
2020-02-04 18:56 ` Michael S. Tsirkin
2020-02-04 18:56 ` Michael S. Tsirkin
2020-02-04 19:17 ` David Hildenbrand
2020-02-04 19:17 ` David Hildenbrand
2020-02-04 23:58 ` Tyler Sanderson
2020-02-04 23:58 ` Tyler Sanderson via Virtualization
2020-02-05 0:15 ` Tyler Sanderson
2020-02-05 0:15 ` Tyler Sanderson via Virtualization
2020-02-05 6:57 ` Michael S. Tsirkin
2020-02-05 6:57 ` Michael S. Tsirkin
2020-02-05 19:01 ` Tyler Sanderson
2020-02-05 19:01 ` Tyler Sanderson via Virtualization
2020-02-05 19:22 ` Alexander Duyck
2020-02-05 21:44 ` Tyler Sanderson
2020-02-05 21:44 ` Tyler Sanderson via Virtualization
2020-02-06 11:00 ` David Hildenbrand
2020-02-06 11:00 ` David Hildenbrand
2020-02-03 22:50 ` Nadav Amit
2020-02-03 22:50 ` Nadav Amit via Virtualization
2020-02-04 8:35 ` David Hildenbrand
2020-02-04 8:35 ` David Hildenbrand
2020-02-04 8:40 ` Michael S. Tsirkin
2020-02-04 8:40 ` Michael S. Tsirkin
2020-02-04 8:48 ` David Hildenbrand
2020-02-04 8:48 ` David Hildenbrand
2020-02-04 14:30 ` David Hildenbrand
2020-02-04 14:30 ` David Hildenbrand
2020-02-04 16:50 ` Michael S. Tsirkin
2020-02-04 16:50 ` Michael S. Tsirkin
2020-02-04 16:56 ` David Hildenbrand
2020-02-04 16:56 ` David Hildenbrand
2020-02-04 20:33 ` Michael S. Tsirkin
2020-02-04 20:33 ` [virtio-dev] " Michael S. Tsirkin
2020-02-04 20:33 ` Michael S. Tsirkin
2020-02-05 8:31 ` David Hildenbrand
2020-02-05 8:31 ` [virtio-dev] " David Hildenbrand
2020-02-05 6:52 ` Wang, Wei W
2020-02-05 6:52 ` Wang, Wei W
2020-02-05 7:05 ` Michael S. Tsirkin
2020-02-05 7:05 ` Michael S. Tsirkin
2020-02-05 8:50 ` Wang, Wei W
2020-02-05 8:50 ` Wang, Wei W
2020-02-05 6:49 ` Wang, Wei W
2020-02-05 6:49 ` Wang, Wei W
2020-02-05 8:19 ` David Hildenbrand
2020-02-05 8:19 ` David Hildenbrand
2020-02-05 8:54 ` Wang, Wei W
2020-02-05 8:54 ` Wang, Wei W
2020-02-05 8:56 ` David Hildenbrand
2020-02-05 8:56 ` David Hildenbrand
2020-02-05 9:00 ` Wang, Wei W [this message]
2020-02-05 9:00 ` Wang, Wei W
2020-02-05 9:05 ` David Hildenbrand
2020-02-05 9:05 ` David Hildenbrand
2020-02-05 9:19 ` Wang, Wei W
2020-02-05 9:19 ` Wang, Wei W
2020-02-05 9:22 ` David Hildenbrand
2020-02-05 9:22 ` David Hildenbrand
2020-02-05 9:35 ` Wang, Wei W
2020-02-05 9:35 ` Wang, Wei W
2020-02-05 9:37 ` David Hildenbrand
2020-02-05 9:37 ` David Hildenbrand
2020-02-05 9:49 ` Wang, Wei W
2020-02-05 9:49 ` Wang, Wei W
2020-02-05 9:58 ` David Hildenbrand
2020-02-05 9:58 ` David Hildenbrand
2020-02-05 10:25 ` Michael S. Tsirkin
2020-02-05 10:25 ` Michael S. Tsirkin
2020-02-05 10:42 ` David Hildenbrand
2020-02-05 10:42 ` David Hildenbrand
2020-02-05 9:35 ` Michael S. Tsirkin
2020-02-05 9:35 ` Michael S. Tsirkin
2020-02-05 18:43 ` Tyler Sanderson
2020-02-05 18:43 ` Tyler Sanderson via Virtualization
2020-02-06 9:30 ` Wang, Wei W
2020-02-06 9:30 ` Wang, Wei W
2020-02-05 7:35 ` Nadav Amit
2020-02-05 7:35 ` Nadav Amit via Virtualization
2020-02-05 8:19 ` David Hildenbrand
2020-02-05 8:19 ` David Hildenbrand
2020-02-05 10:27 ` Michael S. Tsirkin
2020-02-05 10:27 ` Michael S. Tsirkin
2020-02-05 10:43 ` David Hildenbrand
2020-02-05 10:43 ` David Hildenbrand
2020-01-30 22:46 ` Tyler Sanderson
2020-01-30 22:46 ` Tyler Sanderson via Virtualization
2020-02-02 0:21 ` David Rientjes via Virtualization
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