On 10 January 2012 02:54, Suresh Siddha [off-list ref] wrote:

On Mon, 2012-01-09 at 15:29 +0100, Vincent Guittot wrote:

quoted

Hi Peter,

I'm also using sched_mc level for doing powersaving load balance on
ARM platform and we have real benefits.

hi Vincent, Can you elaborate on your platform topology where you see
the benefits?

Hi Suresh,

I'm using dual/quad cores ARM platform. When sched_mc is different
from 0, the topology is changed from 1 socket/cluster to 2 virtual
sockets/clusters with 1 or 2 cores in each cluster.  For low cpu load
situation, the tasks are gathered in 1 virtual socket and let the
cores in the other socket to enter idle state thanks to cpuidle. On
ARM platform, cores in a cluster can enter interesting idle state even
if the complete cluster can't reach a deep idle state.
With dual cores platform, i'm increasing the cpu_power to gather tasks
on 1 core when cores are at lowest frequency. In fact i'm detecting a
low cpu load (only small tasks are running) and ensure that these
small tasks are kept on 1 core.

Regards,
Vincent

on x86, 'sched_mc' was designed for the case of consolidating load into
one socket before using another idle socket.

Just wondering if this is your use case too or if you are consolidating
at a different topological level.

thanks,
suresh