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

2015-04-28 Thread Chris Metcalf
On 04/24/2015 03:24 PM, r...@redhat.com wrote: From: Rik van Riel 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 ma

[PATCH 2/2] show nohz_full cpus in sysfs

2015-04-24 Thread riel
From: Rik van Riel 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 othe

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

2015-03-28 Thread Frederic Weisbecker
On Sat, Mar 28, 2015 at 12:15:56PM -0400, Rik van Riel wrote: > On 03/28/2015 12:02 PM, Frederic Weisbecker wrote: > > 2015-03-27 22:50 GMT+01:00 : > >> From: Rik van Riel > >> > >> Currently there is no way to query which CPUs are in nohz_full > >> mode from userspace. > > > > Well you can watc

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

2015-03-28 Thread Rik van Riel
On 03/28/2015 12:02 PM, Frederic Weisbecker wrote: > 2015-03-27 22:50 GMT+01:00 : >> From: Rik van Riel >> >> Currently there is no way to query which CPUs are in nohz_full >> mode from userspace. > > Well you can watch dmesg | grep NO_HZ > But surely sysfs is more convenient from an app. > > I

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

2015-03-28 Thread Frederic Weisbecker
2015-03-27 22:50 GMT+01:00 : > From: Rik van Riel > > Currently there is no way to query which CPUs are in nohz_full > mode from userspace. Well you can watch dmesg | grep NO_HZ But surely sysfs is more convenient from an app. I guess it's ok, as long as it's strictly Read Only. Here it seems t

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

2015-03-28 Thread Mike Galbraith
On Sat, 2015-03-28 at 09:35 -0400, Rik van Riel wrote: > It can be used by programs like irqbalance to avoid binding IRQs > to isolated or nohz_full CPUs, by libvirt to know which CPUs do > not get load balancing of SCHED_OTHER tasks, etc... Ok, other system packages learning to avoid these does

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

2015-03-28 Thread Rik van Riel
On 03/28/2015 12:18 AM, Mike Galbraith wrote: > On Fri, 2015-03-27 at 17:50 -0400, r...@redhat.com wrote: >> From: Rik van Riel >> >> Currently there is no way to query which CPUs are in nohz_full >> mode from userspace. > > Hm, they're both (as of your last set) invariant. So are most of the o

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

2015-03-27 Thread Mike Galbraith
On Fri, 2015-03-27 at 17:50 -0400, r...@redhat.com wrote: > From: Rik van Riel > > Currently there is no way to query which CPUs are in nohz_full > mode from userspace. Hm, they're both (as of your last set) invariant. Is this so an HPC app can automatically bind itself or something? You can't

[PATCH 2/2] show nohz_full cpus in sysfs

2015-03-27 Thread riel
From: Rik van Riel 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 Signed-off-by: Rik van Riel --- drivers/base/cpu.c | 17 +