[Some people who received this message don't often get email from ying.huang@xxxxxxxxx. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]Yes, in practice, we only proactively compress anonymous pages and do not
Huan Yang <link@xxxxxxxx> writes:
在 2023/11/8 22:06, Michal Hocko 写道:If so, is it better only to reclaim private anonymous pages explicitly?
[Some people who received this message don't often get email from mhocko@xxxxxxxx. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]When an application is frozen, it usually means that we predict that
On Wed 08-11-23 14:58:11, Huan Yang wrote:
In some cases, we need to selectively reclaim file pages or anonymousCould you explain why? And also why do you need to swap out in that
pages in an unbalanced manner.
For example, when an application is pushed to the background and frozen,
it may not be opened for a long time, and we can safely reclaim the
application's anonymous pages, but we do not want to touch the file pages.
case?
it will not be
used for a long time. In order to proactively save some memory, our
strategy will
choose to compress the application's private data into zram. And we
will also
select some of the cold application data that we think is in zram and
swap it out.
The above operations assume that anonymous pages are private to the
application.
Add another option for that?
After the application is frozen, compressing these pages into zram canIf so, swappiness should be high system-wise?
save memory
to some extent without worrying about frequent refaults.
And the cost of refaults on zram is lower than that of IO.
--
Best Regards,
Huang, Ying
So, maybe pass swappiness into sc and keep a single reclamation ensure thatThis patchset extends the proactive reclaim interface to achieveOther have already touched on this in other replies but v2 doesn't have
unbalanced reclamation. Users can control the reclamation tendency by
inputting swappiness under the original interface. Specifically, users
can input special values to extremely reclaim specific pages.
a per-memcg swappiness
Example:In general this is a bad semantic. The operation shouldn't have side
echo "1G" 200 > memory.reclaim (only reclaim anon)
echo "1G" 0 > memory.reclaim (only reclaim file)
echo "1G" 1 > memory.reclaim (only reclaim file)
Note that when performing unbalanced reclamation, the cgroup swappiness
will be temporarily adjusted dynamically to the input value. Therefore,
if the cgroup swappiness is further modified during runtime, there may
be some errors.
effect that are potentially visible for another operation.
swappiness is not changed?
Or, it's a bad idea that use swappiness to control unbalance reclaim.
--
Michal Hocko
SUSE Labs