From: "Michael S. Tsirkin" <mst@redhat.com>
To: "Wang, Wei W" <wei.w.wang@intel.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 02:05:20 -0500 [thread overview]
Message-ID: <20200205015911-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <286AC319A985734F985F78AFA26841F73E41F10F@shsmsx102.ccr.corp.intel.com>
On Wed, Feb 05, 2020 at 06:52:34AM +0000, Wang, Wei W wrote:
> On Wednesday, February 5, 2020 12:50 AM, Michael S. Tsirkin wrote:
> > > Michael, any clue on which event we have to wait with
> > > VIRTIO_BALLOON_F_MUST_TELL_HOST? IMHO, I don't think
> > > VIRTIO_BALLOON_F_MUST_TELL_HOST applies to
> > > VIRTIO_BALLOON_F_FREE_PAGE_HINT and we'd better document that. It
> > introduces complexity with no clear benefit.
> >
> > I meant that we must wait for host to see the hint.
>
> Why?
>
> Best,
> Wei
Well if we did the hint would be reliable, allowing host to immediately
drop any pages it gets in the hint. Originally I wanted to speed up
hinting by never waiting for host, but that does not seem to be what was
implemented: the only place we don't wait is the shrinker and it seems a
waste that we introduced complexity to host without getting any real
benefit out of it.
VIRTIO_BALLOON_F_MUST_TELL_HOST doesn't really apply to hinting
right now, so we could have used it to mean "hints must wait for host
to use buffers". I'm afraid it's already a wasted opportunity at
this point, reusing it isn't worth the compatibility headaches.
--
MST
WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com>
To: "Wang, Wei W" <wei.w.wang@intel.com>
Cc: David Hildenbrand <david@redhat.com>,
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 02:05:20 -0500 [thread overview]
Message-ID: <20200205015911-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <286AC319A985734F985F78AFA26841F73E41F10F@shsmsx102.ccr.corp.intel.com>
On Wed, Feb 05, 2020 at 06:52:34AM +0000, Wang, Wei W wrote:
> On Wednesday, February 5, 2020 12:50 AM, Michael S. Tsirkin wrote:
> > > Michael, any clue on which event we have to wait with
> > > VIRTIO_BALLOON_F_MUST_TELL_HOST? IMHO, I don't think
> > > VIRTIO_BALLOON_F_MUST_TELL_HOST applies to
> > > VIRTIO_BALLOON_F_FREE_PAGE_HINT and we'd better document that. It
> > introduces complexity with no clear benefit.
> >
> > I meant that we must wait for host to see the hint.
>
> Why?
>
> Best,
> Wei
Well if we did the hint would be reliable, allowing host to immediately
drop any pages it gets in the hint. Originally I wanted to speed up
hinting by never waiting for host, but that does not seem to be what was
implemented: the only place we don't wait is the shrinker and it seems a
waste that we introduced complexity to host without getting any real
benefit out of it.
VIRTIO_BALLOON_F_MUST_TELL_HOST doesn't really apply to hinting
right now, so we could have used it to mean "hints must wait for host
to use buffers". I'm afraid it's already a wasted opportunity at
this point, reusing it isn't worth the compatibility headaches.
--
MST
next prev parent reply other threads:[~2020-02-05 7:05 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 via Virtualization
2020-01-30 19:59 ` Tyler Sanderson
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 via Virtualization
2020-02-03 20:32 ` Tyler Sanderson
2020-02-03 21:22 ` Alexander Duyck
2020-02-03 23:16 ` Tyler Sanderson via Virtualization
2020-02-03 23:16 ` Tyler Sanderson
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 via Virtualization
2020-02-04 18:52 ` Tyler Sanderson
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 via Virtualization
2020-02-04 23:58 ` Tyler Sanderson
2020-02-05 0:15 ` Tyler Sanderson via Virtualization
2020-02-05 0:15 ` Tyler Sanderson
2020-02-05 6:57 ` Michael S. Tsirkin
2020-02-05 6:57 ` Michael S. Tsirkin
2020-02-05 19:01 ` Tyler Sanderson via Virtualization
2020-02-05 19:01 ` Tyler Sanderson
2020-02-05 19:22 ` Alexander Duyck
2020-02-05 21:44 ` Tyler Sanderson via Virtualization
2020-02-05 21:44 ` Tyler Sanderson
2020-02-06 11:00 ` David Hildenbrand
2020-02-06 11:00 ` David Hildenbrand
2020-02-03 22:50 ` Nadav Amit via Virtualization
2020-02-03 22:50 ` Nadav Amit
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 ` [virtio-dev] " Michael S. Tsirkin
2020-02-04 20:33 ` Michael S. Tsirkin
2020-02-04 20:33 ` Michael S. Tsirkin
2020-02-05 8:31 ` [virtio-dev] " David Hildenbrand
2020-02-05 8:31 ` 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 [this message]
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
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 via Virtualization
2020-02-05 18:43 ` Tyler Sanderson
2020-02-06 9:30 ` Wang, Wei W
2020-02-06 9:30 ` Wang, Wei W
2020-02-05 7:35 ` Nadav Amit via Virtualization
2020-02-05 7:35 ` Nadav Amit
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 via Virtualization
2020-01-30 22:46 ` Tyler Sanderson
2020-02-02 0:21 ` David Rientjes via Virtualization
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