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Date:   Thu, 19 Nov 2020 08:33:19 +0800
From:   Tao Zhou <t1zhou@163.com>
To:     "Guilherme G. Piccoli" <gpiccoli@canonical.com>
Cc:     vincent.guittot@linaro.org, bsegall@google.com,
        dietmar.eggemann@arm.com, juri.lelli@redhat.com,
        zohooouoto@zoho.com.cn, mgorman@suse.de, mingo@redhat.com,
        ouwen210@hotmail.com, pauld@redhat.com, peterz@infradead.org,
        pkondeti@codeaurora.org, rostedt@goodmis.org,
        Jay Vosburgh <jay.vosburgh@canonical.com>,
        Gavin Guo <gavin.guo@canonical.com>, halves@canonical.com,
        nivedita.singhvi@canonical.com, linux-kernel@vger.kernel.org,
        t1zhou@163.com
Subject: Re: [PATCH v3] sched/fair: fix unthrottle_cfs_rq for leaf_cfs_rq list
Message-ID: <20201119003319.GA6805@geo.homenetwork>
References: <17fc60a3-cc50-7cff-eb46-904c2f0c416e@canonical.com>
 <20201118235015.GB6015@geo.homenetwork>
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On Thu, Nov 19, 2020 at 07:50:15AM +0800, Tao Zhou wrote:
> On Wed, Nov 18, 2020 at 07:56:38PM -0300, Guilherme G. Piccoli wrote:
> > Hi Vincent (and all CCed), I'm sorry to ping about such "old" patch, but
> > we experienced a similar condition to what this patch addresses; it's an
> > older kernel (4.15.x) but when suggesting the users to move to an
> > updated 5.4.x kernel, we noticed that this patch is not there, although
> > similar ones are (like [0] and [1]).
> > 
> > So, I'd like to ask if there's any particular reason to not backport
> > this fix to stable kernels, specially the longterm 5.4. The main reason
> > behind the question is that the code is very complex for non-experienced
> > scheduler developers, and I'm afraid in suggesting such backport to 5.4
> > and introduce complex-to-debug issues.
> > 
> > Let me know your thoughts Vincent (and all CCed), thanks in advance.
> > Cheers,
> > 
> > 
> > Guilherme
> > 
> > 
> > P.S. For those that deleted this thread from the email client, here's a
> > link:
> > https://lore.kernel.org/lkml/20200513135528.4742-1-vincent.guittot@linaro.org/
> > 
> > 
> > [0]
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fe61468b2cb
> > 
> > [1]
> > https://lore.kernel.org/lkml/20200506141821.GA9773@lorien.usersys.redhat.com/
> > <- great thread BTW!
> 
> 'sched/fair: Fix unthrottle_cfs_rq() for leaf_cfs_rq list" failed to apply to
> 5.4-stable tree'
> 
> You could check above. But I do not have the link about this. Can't search it
> on LKML web: https://lore.kernel.org/lkml/
> 
> BTW: 'ouwen210@hotmail.com' and 'zohooouoto@zoho.com.cn' all is myself.
> 
> Sorry for the confusing..
> 
> Thanks.

Sorry again. I forget something. It is in the stable.

Here it is:

  https://lore.kernel.org/stable/159041776924279@kroah.com/