Re: [PATCH] mm, memcg: cg2 memory{.swap,}.peak write handlers

[Michal Hocko <mhocko@suse.com>]

On Wed 17-07-24 16:44:53, Johannes Weiner wrote:
[...]
> The problem is that once global resetting is allowed, it makes the
> number reported in memory.peak unreliable for everyone. You just don't
> know, and can't tell, if somebody wrote to it recently. It's not too
> much of a leap to say this breaks the existing interface contract.

I do not remember any bug reports from v1 where there was a max usage
misreported because of uncoordinated value reseting. So while you are
right that this is theoretically possible I am not convinced this is a
real problem in practice.

On the other hand it seems there is a wider agreement this shouldn't be
added to v2 and I do respect that.
 
> You have to decide whether the above is worth implementing. But my
> take is that the downsides of the simpler solution outweigh its
> benefits.

While this seems quite elegant I am not convinced this is really worth
the additional code for a metric like peak memory consumption which is a
very limited metric in a presence of memory reclaim.

Thanks!
-- 
Michal Hocko
SUSE Labs