From: Thomas Gleixner <tglx@linutronix.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Long Li <longli@microsoft.com>, Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Keith Busch <keith.busch@intel.com>, Jens Axboe <axboe@fb.com>,
Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
John Garry <john.garry@huawei.com>,
Hannes Reinecke <hare@suse.com>,
linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org,
Daniel Lezcano <daniel.lezcano@linaro.org>
Subject: Re: [PATCH 1/4] softirq: implement IRQ flood detection mechanism
Date: Wed, 28 Aug 2019 16:07:19 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.21.1908281605190.23149@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20190828135054.GA23861@ming.t460p>
On Wed, 28 Aug 2019, Ming Lei wrote:
> On Wed, Aug 28, 2019 at 01:23:06PM +0200, Thomas Gleixner wrote:
> > On Wed, 28 Aug 2019, Ming Lei wrote:
> > > On Wed, Aug 28, 2019 at 01:09:44AM +0200, Thomas Gleixner wrote:
> > > > > > Also how is that supposed to work when sched_clock is jiffies based?
> > > > >
> > > > > Good catch, looks ktime_get_ns() is needed.
> > > >
> > > > And what is ktime_get_ns() returning when the only available clocksource is
> > > > jiffies?
> > >
> > > IMO, it isn't one issue. If the only clocksource is jiffies, we needn't to
> > > expect high IO performance. Then it is fine to always handle the irq in
> > > interrupt context or thread context.
> > >
> > > However, if it can be recognized runtime, irq_flood_detected() can
> > > always return true or false.
> >
> > Right. The clocksource is determined at runtime. And if there is no high
> > resolution clocksource then that function will return crap.
>
> This patch still works even though the only clocksource is jiffies.
Works by some definition of works, right?
> > Well, yes. But it's trivial enough to utilize parts of it for your
> > purposes.
>
> >From the code of kernel/irq/timing.c:
>
> 1) record_irq_time() only records the start time of one irq, and not
> consider the time taken in interrupt handler, so we can't figure out
> the real interval between two do_IRQ() on one CPU
I said utilize and that means that the infrastructure can be used and
extended. I did not say that it solves your problem, right?
> 2) irq/timing doesn't cover softirq
That's solvable, right?
> Daniel, could you take a look and see if irq flood detection can be
> implemented easily by irq/timing.c?
I assume you can take a look as well, right?
Thanks,
tglx
next prev parent reply other threads:[~2019-08-28 14:07 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-27 8:53 [PATCH 0/4] genirq/nvme: add IRQF_RESCUE_THREAD for avoiding IRQ flood Ming Lei
2019-08-27 8:53 ` [PATCH 1/4] softirq: implement IRQ flood detection mechanism Ming Lei
2019-08-27 14:42 ` Thomas Gleixner
2019-08-27 16:19 ` Thomas Gleixner
2019-08-27 23:04 ` Ming Lei
2019-08-27 23:12 ` Thomas Gleixner
2019-08-27 22:58 ` Ming Lei
2019-08-27 23:09 ` Thomas Gleixner
2019-08-28 11:06 ` Ming Lei
2019-08-28 11:23 ` Thomas Gleixner
2019-08-28 13:50 ` Ming Lei
2019-08-28 14:07 ` Thomas Gleixner [this message]
2019-09-03 3:30 ` Ming Lei
2019-09-03 5:59 ` Daniel Lezcano
2019-09-03 6:31 ` Ming Lei
2019-09-03 6:40 ` Daniel Lezcano
2019-09-03 7:28 ` Ming Lei
2019-09-03 7:50 ` Daniel Lezcano
2019-09-03 9:30 ` Ming Lei
2019-09-04 17:07 ` Bart Van Assche
2019-09-04 17:31 ` Daniel Lezcano
2019-09-04 17:38 ` Bart Van Assche
2019-09-04 18:02 ` Peter Zijlstra
2019-09-04 19:47 ` Bart Van Assche
2019-09-05 9:11 ` Ming Lei
2019-09-05 9:06 ` Ming Lei
2019-09-05 10:37 ` Daniel Lezcano
2019-09-06 1:22 ` Long Li
2019-09-06 4:36 ` Daniel Lezcano
2019-09-06 4:44 ` Long Li
2019-09-06 1:48 ` Ming Lei
2019-09-06 5:14 ` Daniel Lezcano
2019-09-06 18:30 ` Sagi Grimberg
2019-09-06 18:52 ` Keith Busch
2019-09-07 0:01 ` Ming Lei
2019-09-10 3:10 ` Sagi Grimberg
2019-09-18 0:00 ` Long Li
2019-09-20 17:14 ` Sagi Grimberg
2019-09-20 19:12 ` Long Li
2019-09-20 20:45 ` Sagi Grimberg
2019-09-24 0:57 ` Long Li
2019-09-18 14:37 ` Ming Lei
2019-09-20 17:09 ` Sagi Grimberg
2019-09-06 14:18 ` Keith Busch
2019-09-06 17:50 ` Long Li
2019-09-06 22:19 ` Ming Lei
2019-09-06 22:25 ` Keith Busch
2019-09-06 23:13 ` Ming Lei
2019-09-10 0:24 ` Ming Lei
2019-09-03 8:09 ` Thomas Gleixner
2019-09-03 9:24 ` Ming Lei
2019-08-29 6:15 ` Long Li
2019-08-30 0:55 ` Ming Lei
2019-08-27 8:53 ` [PATCH 2/4] genirq: add IRQF_RESCUE_THREAD Ming Lei
2019-08-27 8:53 ` [PATCH 3/4] nvme: pci: pass IRQF_RESCURE_THREAD to request_threaded_irq Ming Lei
2019-08-27 9:06 ` Johannes Thumshirn
2019-08-27 9:09 ` Ming Lei
2019-08-27 9:12 ` Johannes Thumshirn
2019-08-27 14:34 ` Keith Busch
2019-08-27 14:44 ` Keith Busch
2019-08-27 15:10 ` Bart Van Assche
2019-08-28 1:45 ` Ming Lei
2019-08-27 8:53 ` [PATCH 4/4] genirq: use irq's affinity for threaded irq with IRQF_RESCUE_THREAD Ming Lei
2019-08-27 14:35 ` Keith Busch
2019-09-06 8:50 ` John Garry
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