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SubjectRe: [-mm] Add an owner to the mm_struct (v8)
Paul Menage wrote:
> On Tue, Apr 8, 2008 at 12:05 AM, Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
>> Paul Menage wrote:
>> > On Mon, Apr 7, 2008 at 11:52 PM, Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
>> >> I agree, but like I said earlier, this was the easily available ready made
>> >> application I found. Do you know of any other highly threaded micro benchmark?
>> >>
>> >
>> > How about a simple program that creates N threads that just sleep,
>> > then has the main thread exit?
>> >
>>
>> That is not really representative of anything. I have that program handy. How do
>> we measure the impact on throughput?
>
> It's very representative of how much additional overhead in terms of
> mm->owner churn there is in a large multi-threaded application
> exiting, which is the thing that you're trying to optimize with the
> delayed thread group leader checks.
>

I see almost no overhead after the notification change optimization (notify only
if owner belongs to a different cgroup).

My program creates n processes with k threads each and forces the thread group
leader to exit. For my experiment I created 10 processes with 800 threads each
(NOTE: you need to change ulimit -s for this to work).

I am going to remove the delay_group_leader() optimization and submit v9.

--
Warm Regards,
Balbir Singh
Linux Technology Center
IBM, ISTL


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