From: David Hildenbrand <david@redhat.com>
To: "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: Tue, 4 Feb 2020 09:48:48 +0100 [thread overview]
Message-ID: <cdf72b78-37ea-28d6-e3aa-c19ecda8465a@redhat.com> (raw)
In-Reply-To: <20200204033657-mutt-send-email-mst@kernel.org>
On 04.02.20 09:40, Michael S. Tsirkin wrote:
> On Tue, Feb 04, 2020 at 09:35:21AM +0100, David Hildenbrand wrote:
>>>>> I would say reverting probably makes sense. I'm not sure there is much
>>>>> value to having a shrinker running deflation when you are actively trying
>>>>> to increase the balloon. It would make more sense to wait until you are
>>>>> actually about to start hitting oom.
>>>>
>>>> I think the shrinker makes sense for free page hinting feature
>>>> (everything on free_page_list).
>>>>
>>>> So instead of only reverting, I think we should split it up and always
>>>> register the shrinker for VIRTIO_BALLOON_F_FREE_PAGE_HINT and the OOM
>>>> notifier (as before) for VIRTIO_BALLOON_F_MUST_TELL_HOST.
>>
>> s/VIRTIO_BALLOON_F_MUST_TELL_HOST/VIRTIO_BALLOON_F_DEFLATE_ON_OOM/
>>
>> :)
>
> Well VIRTIO_BALLOON_F_MUST_TELL_HOST is also broken by shrinker
> with VIRTIO_BALLOON_F_FREE_PAGE_HINT as that code adds buffers
> but does not wait for them to be used even with VIRTIO_BALLOON_F_MUST_TELL_HOST.
> We never noticed because QEMU does not advertize
> VIRTIO_BALLOON_F_MUST_TELL_HOST.
Will try to figure out how to best undo this mess :)
>
>
>>>>
>>>> (Of course, adapting what is being done in the shrinker and in the OOM
>>>> notifier)
>>>
>>> David,
>>>
>>> Please keep me posted. I decided to adapt the same solution as the virtio
>>> balloon for the VMware balloon. If the verdict is that this is damaging and
>>> the OOM notifier should be used instead, I will submit patches to move to
>>> OOM notifier as well.
>>
>> Will do. It all sounds sub-optimal to me at this point ... but I prefer
>> the old variant where a simple "drop_slab()" won't deflate the balloon.
>> That looks broken to me.
>
> Okay. Could you post a patch?
I can give it a shot.
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2020-02-04 8:48 UTC|newest]
Thread overview: 59+ 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 15:20 ` Michael S. Tsirkin
2020-01-30 15:23 ` David Hildenbrand
2020-01-30 15:31 ` Wang, Wei W
2020-01-30 19:59 ` Tyler Sanderson via Virtualization
2020-02-03 13:11 ` Michael S. Tsirkin
[not found] ` <5ac131de8e3b7fc1fafd05a61feb5f6889aeb917.camel@linux.intel.com>
2020-02-03 16:34 ` David Hildenbrand
2020-02-03 17:03 ` Michael S. Tsirkin
2020-02-03 20:32 ` Tyler Sanderson via Virtualization
[not found] ` <2584af9b8d358faf27ee838fdab2be594e255433.camel@linux.intel.com>
2020-02-03 23:16 ` Tyler Sanderson via Virtualization
2020-02-04 5:45 ` Michael S. Tsirkin
2020-02-04 8:29 ` David Hildenbrand
2020-02-04 18:52 ` Tyler Sanderson via Virtualization
2020-02-04 18:56 ` Michael S. Tsirkin
2020-02-04 19:17 ` David Hildenbrand
2020-02-04 23:58 ` Tyler Sanderson via Virtualization
2020-02-05 0:15 ` Tyler Sanderson via Virtualization
2020-02-05 6:57 ` Michael S. Tsirkin
2020-02-05 19:01 ` Tyler Sanderson via Virtualization
[not found] ` <b280e9902d1a40dab8ba65fc1498d897a4b193e4.camel@linux.intel.com>
2020-02-05 21:44 ` Tyler Sanderson via Virtualization
2020-02-06 11:00 ` David Hildenbrand
2020-02-03 22:50 ` Nadav Amit via Virtualization
2020-02-04 8:35 ` David Hildenbrand
2020-02-04 8:40 ` Michael S. Tsirkin
2020-02-04 8:48 ` David Hildenbrand [this message]
2020-02-04 14:30 ` David Hildenbrand
2020-02-04 16:50 ` Michael S. Tsirkin
2020-02-04 16:56 ` David Hildenbrand
2020-02-04 20:33 ` Michael S. Tsirkin
2020-02-05 8:31 ` David Hildenbrand
2020-02-05 6:52 ` Wang, Wei W
2020-02-05 7:05 ` Michael S. Tsirkin
2020-02-05 8:50 ` Wang, Wei W
2020-02-05 6:49 ` Wang, Wei W
2020-02-05 8:19 ` David Hildenbrand
2020-02-05 8:54 ` Wang, Wei W
2020-02-05 8:56 ` David Hildenbrand
2020-02-05 9:00 ` Wang, Wei W
2020-02-05 9:05 ` David Hildenbrand
2020-02-05 9:19 ` Wang, Wei W
2020-02-05 9:22 ` David Hildenbrand
2020-02-05 9:35 ` Wang, Wei W
2020-02-05 9:37 ` David Hildenbrand
2020-02-05 9:49 ` Wang, Wei W
2020-02-05 9:58 ` David Hildenbrand
2020-02-05 10:25 ` Michael S. Tsirkin
2020-02-05 10:42 ` David Hildenbrand
2020-02-05 9:35 ` Michael S. Tsirkin
2020-02-05 18:43 ` Tyler Sanderson via Virtualization
2020-02-06 9:30 ` Wang, Wei W
2020-02-05 7:35 ` Nadav Amit via Virtualization
2020-02-05 8:19 ` David Hildenbrand
2020-02-05 10:27 ` Michael S. Tsirkin
2020-02-05 10:43 ` David Hildenbrand
2020-01-30 22:46 ` Tyler Sanderson via Virtualization
2020-02-02 0:21 ` David Rientjes via Virtualization
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