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Subject: Re: [PATCH RFC] sched: Add a per-thread core scheduling
 interface(Internet mail)
Thread-Topic: [PATCH RFC] sched: Add a per-thread core scheduling
 interface(Internet mail)
Thread-Index: AQHWLvXKFOwpUhEtgUmeB0cRYW4c1KixZ1AA
Date:   Thu, 21 May 2020 04:09:50 +0000
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 <20200520222642.70679-1-joel@joelfernandes.org>
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> On May 21, 2020, at 6:26 AM, Joel Fernandes (Google) <joel@joelfernandes.=
org> wrote:
>=20
> Add a per-thread core scheduling interface which allows a thread to tag
> itself and enable core scheduling. Based on discussion at OSPM with
> maintainers, we propose a prctl(2) interface accepting values of 0 or 1.
> 1 - enable core scheduling for the task.
> 0 - disable core scheduling for the task.
>=20
> Special cases:
> (1)
> The core-scheduling patchset contains a CGroup interface as well. In
> order for us to respect users of that interface, we avoid overriding the
> tag if a task was CGroup-tagged because the task becomes inconsistent
> with the CGroup tag. Instead return -EBUSY.
>=20
> (2)
> If a task is prctl-tagged, allow the CGroup interface to override
> the task's tag.
>=20
> ChromeOS will use core-scheduling to securely enable hyperthreading.
> This cuts down the keypress latency in Google docs from 150ms to 50ms
> while improving the camera streaming frame rate by ~3%.
Hi,
Are the performance improvements compared to the hyperthreading disabled sc=
enario or not?
Could you help to explain how the keypress latency improvement comes with c=
ore-scheduling?

Thanks a lot.

Regards,
Jiang