On Thu, Mar 26, 2020 at 2:47 PM Waiman Long [off-list ref] wrote:

On 3/26/20 4:05 PM, Sonny Rao wrote:

quoted

quoted

I think Tejun is concerned about a change in the default behavior of
cpuset v1.

There is a special v2 mode for cpuset that is enabled by the mount
option "cpuset_v2_mode". This causes the cpuset v1 to adopt some of the
v2 behavior. I introduced this v2 mode a while back to address, I think,
a similar concern. Could you try that to see if it is able to address
your problem? If not, you can make some code adjustment within the
framework of the v2 mode. As long as it is an opt-in, I think we are
open to further change.

I am surprised if anyone actually wants this behavior, we (Chrome OS)
found out about it accidentally, and then found that Android had been
carrying a patch to fix it.  And if it were a desirable behavior then
why isn't it an option in v2?

I am a bit confused. The v2 mode make cpuset v1 behaves more like cpuset
v2. The original v1 behavior has some obvious issue that was fixed in
v2. So what v2 option are you talking about?

I was merely pointing out the behavior of the v1 implementation is so
undesirable that it wasn't kept at all in v2.  IMHO, it's a bug that
should be fixed, and I think it's possible to keep the old behavior if
all cpus are offlined, but since you've added this option we can use
it instead.

Regards,
Longman