Re: [PATCH 2/2] show nohz_full cpus in sysfs

[Chris Metcalf]

On 04/24/2015 03:24 PM, riel@xxxxxxxxxx wrote:
> From: Rik van Riel<riel@xxxxxxxxxx>
>
> Currently there is no way to query which CPUs are in nohz_full
> mode from userspace.
>
> Export the CPU list running in nohz_full mode in sysfs,
> specifically in the file /sys/devices/system/cpu/nohz_full
>
> This can be used by system management tools like libvirt,
> openstack, and others to ensure proper task placement.
>
> Signed-off-by: Rik van Riel<riel@xxxxxxxxxx>
> ---
>   drivers/base/cpu.c | 17 +++++++++++++++++
>   1 file changed, 17 insertions(+)

In the arch/tile distribution with our "dataplane" support, we have
traditionally had a /sys/devices/system/cpu/dataplane file with
the same semantics you are proposing.  It's definitely helpful
to userspace applications figuring out how to appropriately take
over the machine they are being run on.

Acked-by: Chris Metcalf <cmetcalf@xxxxxxxxxx>
--
Chris Metcalf, EZChip Semiconductor
http://www.ezchip.com
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