linux-kernel - Re: [PATCH] x86/resctrl: fix redundant task movement

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Date:   Tue, 28 Jan 2020 16:59:22 -0800
From:   Fenghua Yu <fenghua.yu@...el.com>
To:     Shakeel Butt <shakeelb@...gle.com>
Cc:     Reinette Chatre <reinette.chatre@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Stephane Eranian <eranian@...gle.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/resctrl: fix redundant task movement

On Tue, Jan 28, 2020 at 04:22:22PM -0800, Shakeel Butt wrote:
> Currently a task can be moved to a rdtgroup multiple times or between
> resource or monitoring groups. This can cause multiple task works are
> added, waste memory and degrade performance.
> 
> To fix the issue, only move the task to a rdtgroup when the task
> is not in the rdgroup. Don't try to move the task to the rdtgroup
> again when the task is already in the rdtgroup.

Hi, Shakeel,

Acutally we are working on replacing the callback by a synchronous way
to update closid and rmid when moving a task to a resource group. The
reason is the task may use old (even invalid) closid and rmid before
they are updated.

With the new way to update closid and rmid, the issues related to
the callbacks will be fixed as well.

We will release the new patches soon.

Thanks.

-Fenghua