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Date:   Wed, 10 Apr 2019 12:36:33 +0800
From:   Aaron Lu <aaron.lu@linux.alibaba.com>
To:     Tim Chen <tim.c.chen@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>
Cc:     mingo@kernel.org, tglx@linutronix.de, pjt@google.com,
        torvalds@linux-foundation.org, linux-kernel@vger.kernel.org,
        subhra.mazumdar@oracle.com, fweisbec@gmail.com,
        keescook@chromium.org, kerrnel@google.com,
        Aubrey Li <aubrey.intel@gmail.com>,
        Julien Desfossez <jdesfossez@digitalocean.com>
Subject: Re: [RFC][PATCH 13/16] sched: Add core wide task selection and
 scheduling.
Message-ID: <20190410043633.GA67532@aaronlu>
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On Tue, Apr 09, 2019 at 11:09:45AM -0700, Tim Chen wrote:
> Now that we have accumulated quite a number of different fixes to your orginal
> posted patches.  Would you like to post a v2 of the core scheduler with the fixes?

One more question I'm not sure: should a task with cookie=0, i.e. tasks
that are untagged, be allowed to scheduled on the the same core with
another tagged task?

The current patch seems to disagree on this, e.g. in pick_task(),
if max is already chosen but max->core_cookie == 0, then we didn't care
about cookie and simply use class_pick for the other cpu. This means we
could schedule two tasks with different cookies(one is zero and the
other can be tagged).

But then sched_core_find() only allow idle task to match with any tagged
tasks(we didn't place untagged tasks to the core tree of course :-).

Thoughts? Do I understand this correctly? If so, I think we probably
want to make this clear before v2. I personally feel, we shouldn't allow
untagged tasks(like kernel threads) to match with tagged tasks.