From: David Hildenbrand <david@redhat.com>
To: Tyler Sanderson <tysand@google.com>,
virtualization@lists.linux-foundation.org,
Wei Wang <wei.w.wang@intel.com>,
David Rientjes <rientjes@google.com>
Subject: Re: Balloon pressuring page cache
Date: Wed, 29 Jan 2020 11:31:28 +0100 [thread overview]
Message-ID: <91270a68-ff48-88b0-219c-69801f0c252f@redhat.com> (raw)
In-Reply-To: <CAJuQAmpDUyve2S+oxp9tLUhuRcnddXnNztC5PmYOOCpY6c68xg@mail.gmail.com>
On 29.01.20 01:22, Tyler Sanderson via Virtualization wrote:
> A primary advantage of virtio balloon over other memory reclaim
> mechanisms is that it can pressure the guest's page cache into shrinking.
>
> However, since the balloon driver changed to using the shrinker API
> <https://github.com/torvalds/linux/commit/71994620bb25a8b109388fefa9e99a28e355255a#diff-fd202acf694d9eba19c8c64da3e480c9> this
> use case has become a bit more tricky. I'm wondering what the intended
> device implementation is.
>
> When inflating the balloon against page cache (i.e. no free memory
> remains) vmscan.c will both shrink page cache, but also invoke the
> shrinkers -- including the balloon's shrinker. So the balloon driver
> allocates memory which requires reclaim, vmscan gets this memory by
> shrinking the balloon, and then the driver adds the memory back to the
> balloon. Basically a busy no-op.
>
> If file IO is ongoing during this balloon inflation then the page cache
> could be growing which further puts "back pressure" on the balloon
> trying to inflate. In testing I've seen periods of > 45 seconds where
> balloon inflation makes no net forward progress.
>
> This wasn't a problem before the change to the shrinker API since forced
> balloon deflation only occurred via the OOM notifier callback which was
> invoked only after the page cache had depleted.
>
> Is this new busy behavior working as intended?
Please note that the shrinker will only be registered in case we have
VIRTIO_BALLOON_F_DEFLATE_ON_OOM - (which is AFAIK very rare) - to
implement automatic balloon deflation when the guest is under memory
pressure.
Are you actually experiencing issues with that or did you just stumble
over the code?
--
Thanks,
David / dhildenb
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
next prev parent reply other threads:[~2020-01-29 10:31 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 [this message]
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
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=91270a68-ff48-88b0-219c-69801f0c252f@redhat.com \
--to=david@redhat.com \
--cc=rientjes@google.com \
--cc=tysand@google.com \
--cc=virtualization@lists.linux-foundation.org \
--cc=wei.w.wang@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.