Re: vmstat: On demand vmstat workers V5

From: Christoph Lameter
Date: Thu May 29 2014 - 10:07:56 EST


On Thu, 29 May 2014, Frederic Weisbecker wrote:

> The cpumasks in cpu.c are special as they are the base of the cpumask_var_t
> definition. They are necessary to define nr_cpu_bits which is the base of
> cpumask_var_t allocations. As such they must stay lower level and defined
> on top of NR_CPUS.
>
> But most other cases don't need that huge static bitmap. I actually haven't
> seen any other struct cpumask than isn't based on cpumask_var_t.

Well yes and I am tying directly into that scheme there in cpu.c to
display the active vmstat threads in sysfs. so its the same.

> Please post it on a new thread so it gets noticed by others.

Ok. Will do when we got agreement on the cpumask issue.

I would like to have some way to display the activities on cpus in /sysfs
like I have done here with the active vmstat workers.

What I think we need is display cpumasks for

1. Cpus where the tick is currently off
2. Cpus that have dynticks enabled.
3. Cpus that are idle
4. Cpus that are used for RCU.


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