From: Ming Lei <ming.lei@redhat.com>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Jens Axboe <axboe@fb.com>, Hannes Reinecke <hare@suse.com>,
John Garry <john.garry@huawei.com>,
Sagi Grimberg <sagi@grimberg.me>,
linux-scsi@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
Long Li <longli@microsoft.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-nvme@lists.infradead.org,
Keith Busch <keith.busch@intel.com>,
Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 1/4] softirq: implement IRQ flood detection mechanism
Date: Thu, 5 Sep 2019 17:11:04 +0800 [thread overview]
Message-ID: <20190905091103.GC4432@ming.t460p> (raw)
In-Reply-To: <9b924e48-e217-9c11-c1fb-46c92a82ea2d@acm.org>
On Wed, Sep 04, 2019 at 12:47:13PM -0700, Bart Van Assche wrote:
> On 9/4/19 11:02 AM, Peter Zijlstra wrote:
> > On Wed, Sep 04, 2019 at 10:38:59AM -0700, Bart Van Assche wrote:
> > > I think it is widely known that rdtsc is a relatively slow x86 instruction.
> > > So I expect that using that instruction will cause a measurable overhead if
> > > it is called frequently enough. I'm not aware of any publicly available
> > > measurement data however.
> >
> > https://www.agner.org/optimize/instruction_tables.pdf
> >
> > RDTSC, Ryzen: ~36
> > RDTSC, Skylake: ~20
> >
> > Sadly those same tables don't list the cost of actual exceptions or even
> > IRET :/
>
> Thanks Peter for having looked up these numbers. These numbers are much
> better than last time I checked. Ming, would CONFIG_IRQ_TIME_ACCOUNTING help
> your workload?
In my fio test on azure L80sv2, IRQ_TIME_ACCOUNTING isn't enabled.
However the irq flood detection introduces two RDTSC for each do_IRQ(),
not see obvious IOPS difference.
Thanks,
Ming
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next prev parent reply other threads:[~2019-09-05 9:11 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190827085344.30799-1-ming.lei@redhat.com>
[not found] ` <20190827085344.30799-2-ming.lei@redhat.com>
[not found] ` <alpine.DEB.2.21.1908271633450.1939@nanos.tec.linutronix.de>
[not found] ` <20190827225827.GA5263@ming.t460p>
[not found] ` <alpine.DEB.2.21.1908280104330.1939@nanos.tec.linutronix.de>
[not found] ` <20190828110633.GC15524@ming.t460p>
[not found] ` <alpine.DEB.2.21.1908281316230.1869@nanos.tec.linutronix.de>
[not found] ` <20190828135054.GA23861@ming.t460p>
[not found] ` <alpine.DEB.2.21.1908281605190.23149@nanos.tec.linutronix.de>
2019-09-03 3:30 ` [PATCH 1/4] softirq: implement IRQ flood detection mechanism 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 [this message]
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
[not found] ` <20190827085344.30799-5-ming.lei@redhat.com>
2019-09-06 8:50 ` [PATCH 4/4] genirq: use irq's affinity for threaded irq with IRQF_RESCUE_THREAD John Garry
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