From: Joel Fernandes <joel@joelfernandes.org>
To: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: John Stultz <jstultz@google.com>,
LKML <linux-kernel@vger.kernel.org>,
Connor O'Brien <connoro@google.com>,
John Dias <joaodias@google.com>, Rick Yiu <rickyiu@google.com>,
John Kacur <jkacur@redhat.com>, Qais Yousef <qais.yousef@arm.com>,
Chris Redpath <chris.redpath@arm.com>,
Abhijeet Dharmapurikar <adharmap@quicinc.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
kernel-team@android.com, "J . Avila" <elavila@google.com>
Subject: Re: [PATCH RFC v4 2/3] sched: Avoid placing RT threads on cores handling long softirqs
Date: Sat, 22 Oct 2022 18:34:37 +0000 [thread overview]
Message-ID: <Y1Q3vYjlFt/Imu5w@google.com> (raw)
In-Reply-To: <Y1FDegctcU2LrYGT@li-4a3a4a4c-28e5-11b2-a85c-a8d192c6f089.ibm.com>
On Thu, Oct 20, 2022 at 02:47:54PM +0200, Alexander Gordeev wrote:
> On Wed, Oct 19, 2022 at 03:09:15PM -0700, John Stultz wrote:
>
> Hi John,
>
> [...]
>
> > So I'll go ahead and simplify the check to just the LONG_SOFTIRQ_MASK
> > & (active | pending softirqs) check. This should avoid the need to
> > pull the cpu_rq(cpu)->curr value and simplify things.
>
> In my reading of your approach if you find a way to additionally
> indicate long softirqs being handled by the remote ksoftirqd, it
> would cover all obvious/not-corner cases.
How will that help? The long softirq executing inside ksoftirqd will disable
preemption and prevent any RT task from executing.
Did I miss something?
thanks,
- Joel
next prev parent reply other threads:[~2022-10-22 18:34 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-03 23:20 [RFC PATCH v4 0/3] Softirq -rt Optimizations John Stultz
2022-10-03 23:20 ` [RFC PATCH v4 1/3] softirq: Add generic accessor to percpu softirq_pending data John Stultz
2022-10-03 23:20 ` [RFC PATCH v4 2/3] sched: Avoid placing RT threads on cores handling long softirqs John Stultz
2022-10-04 1:36 ` Hillf Danton
2022-10-04 2:29 ` John Stultz
2022-10-05 0:21 ` Hillf Danton
2022-10-05 1:13 ` John Stultz
2022-10-05 6:01 ` Hillf Danton
2022-10-10 15:42 ` Qais Yousef
2022-10-11 11:18 ` Hillf Danton
2022-10-12 14:10 ` Qais Yousef
2022-10-13 1:43 ` Hillf Danton
2022-10-17 12:40 ` [PATCH RFC " Alexander Gordeev
2022-10-18 3:42 ` John Stultz
2022-10-18 3:59 ` John Stultz
2022-10-18 5:32 ` John Stultz
2022-10-19 9:11 ` Alexander Gordeev
2022-10-19 22:09 ` John Stultz
2022-10-20 0:15 ` Qais Yousef
2022-10-20 12:47 ` Alexander Gordeev
2022-10-22 18:34 ` Joel Fernandes [this message]
2022-10-23 7:45 ` Alexander Gordeev
2022-11-15 7:08 ` John Stultz
2022-11-15 12:55 ` Alexander Gordeev
2022-10-19 11:23 ` Qais Yousef
2022-10-22 18:28 ` [RFC PATCH " Joel Fernandes
2022-11-15 21:36 ` John Stultz
2022-10-03 23:20 ` [RFC PATCH v4 3/3] softirq: defer softirq processing to ksoftirqd if CPU is busy with RT John Stultz
2022-10-04 10:45 ` David Laight
2022-10-04 19:19 ` John Stultz
2022-10-10 16:09 ` Qais Yousef
2022-10-17 14:44 ` Qais Yousef
2022-10-18 0:04 ` John Stultz
2022-10-19 11:01 ` Qais Yousef
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