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Date:   Sat, 5 Dec 2020 21:40:49 +0100
From:   Pavel Machek <pavel@ucw.cz>
To:     Alex Belits <abelits@marvell.com>
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Subject: Re: [PATCH v5 0/9] "Task_isolation" mode
Message-ID: <20201205204049.GA8578@amd>
References: <8d887e59ca713726f4fcb25a316e1e932b02823e.camel@marvell.com>
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Hi!

> General description
>=20
> This is the result of development and maintenance of task isolation
> functionality that originally started based on task isolation patch
> v15 and was later updated to include v16. It provided predictable
> environment for userspace tasks running on arm64 processors alongside
> with full-featured Linux environment. It is intended to provide
> reliable interruption-free environment from the point when a userspace
> task enters isolation and until the moment it leaves isolation or
> receives a signal intentionally sent to it, and was successfully used
> for this purpose. While CPU isolation with nohz provides an
> environment that is close to this requirement, the remaining IPIs and
> other disturbances keep it from being usable for tasks that require
> complete predictability of CPU timing.

So... what kind of guarantees does this aim to provide / what tasks it
is useful for?

For real time response, we have other approaches.

If you want to guarantee performnace of the "isolated" task... I don't
see how that works. Other tasks on the system still compete for DRAM
bandwidth, caches, etc...

So... what is the usecase?
								Pavel
--=20
http://www.livejournal.com/~pavelmachek

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