On Wed, Aug 24, 2022 at 10:21 PM Andrew Morton
[off-list ref] wrote:

On Wed, 24 Aug 2022 21:41:42 -0700 Shakeel Butt [off-list ref] wrote:

quoted

quoted

Did you evaluate the effects of using a per-cpu counter of some form?

Do you mean per-cpu counter for usage or something else?

percpu_counter, perhaps.  Or some hand-rolled thing if that's more suitable.

quoted

The usage
needs to be compared against the limits and accumulating per-cpu is
costly particularly on larger machines,

Well, there are tricks one can play.  For example, only run
__percpu_counter_sum() when `usage' is close to its limit.

I'd suggest flinging together a prototype which simply uses
percpu_counter_read() all the time.  If the performance testing results
are sufficiently promising, then look into the accuracy issues.

Thanks, I will take a stab at that in a week or so.