Re: [PATCH -next] mm: introduce per-node proactive reclaim interface

[Andrew Morton]

On Wed, 4 Sep 2024 18:08:05 -0700 Davidlohr Bueso <dave@xxxxxxxxxxxx> wrote:

> On Wed, 04 Sep 2024, Andrew Morton wrote:\n
> >On Wed,  4 Sep 2024 09:27:40 -0700 Davidlohr Bueso <dave@xxxxxxxxxxxx> wrote:
> >
> >> This adds support for allowing proactive reclaim in general on a
> >> NUMA system. A per-node interface extends support for beyond a
> >> memcg-specific interface, respecting the current semantics of
> >> memory.reclaim: respecting aging LRU and not supporting
> >> artificially triggering eviction on nodes belonging to non-bottom
> >> tiers.
> >>
> >> This patch allows userspace to do:
> >>
> >>      echo 512M swappiness=10 > /sys/devices/system/node/nodeX/reclaim
> >
> >One value per sysfs file is a rule.
> 
> I wasn't aware of it as a rule - is this documented somewhere?

Documentation/filesystems/sysfs.rst, line 62.  Also lots of gregkh
grumpygrams :)

> I ask because I see some others are using space-separated parameters, ie:
> 
> /sys/bus/usb/drivers/foo/new_id
> 
> ... or colons. What would be acceptable? echo "512M:10" > ... ?

Kinda cheating.  But the rule gets violated a lot.