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From: Daniel Wagner <dwagner@suse.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ming Lei <ming.lei@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Jens Axboe <axboe@kernel.dk>,
	linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
	Long Li <longli@microsoft.com>, Ingo Molnar <mingo@redhat.com>,
	Christoph Hellwig <hch@lst.de>,
	Keith Busch <keith.busch@intel.com>,
	Sagi Grimberg <sagi@grimberg.me>,
	John Garry <john.garry@huawei.com>,
	Hannes Reinecke <hare@suse.com>
Subject: Re: [RFC PATCH 2/3] softirq: implement interrupt flood detection
Date: Thu, 19 Dec 2019 11:43:47 +0100	[thread overview]
Message-ID: <20191219104347.ql6shgh2x7hk6iid@boron> (raw)
In-Reply-To: <20191219092319.GX2844@hirez.programming.kicks-ass.net>

Hi,

On Thu, Dec 19, 2019 at 10:23:19AM +0100, Peter Zijlstra wrote:
> On Thu, Dec 19, 2019 at 09:59:48AM +0800, Ming Lei wrote:
> > > So pray tell, why did you not integrate this with IRQ_TIME_ACCOUNTING ?
> > > That already takes a timestamp and does most of what you need.
> > 
> > Yeah, that was the 1st approach I thought of, but IRQ_TIME_ACCOUNTING
> > may be disabled, and enabling it may cause observable effect on IO
> > performance.
> 
> Is that an actual concern, are people disabling it?

In SLE and openSUSE kernels it is disabled for x86_64 at this
point. And if I am not completely misstaken only x86_64 supports it at
this point. I was looking at enable_sched_clock_irqtime() which is
only called from x86_64.

Another thing I noticed get_util_irq() is defined in
kernel/sched/sched.h. I don't think the block/blq-mq.c driver should
include it direclty.

Thanks,
Daniel

ps: A customer observes the same problem as Ming is reporting.

  parent reply	other threads:[~2019-12-19 10:43 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-18  7:19 [RFC PATCH 0/3] softirq/blk-mq: implement interrupt flood detection for avoiding cpu lockup Ming Lei
2019-12-18  7:19 ` [RFC PATCH 1/3] sched/core: add API for exporting runqueue clock Ming Lei
2019-12-18  9:51   ` Peter Zijlstra
2019-12-19  1:29     ` Ming Lei
2019-12-19  9:20       ` Peter Zijlstra
2019-12-18  7:19 ` [RFC PATCH 2/3] softirq: implement interrupt flood detection Ming Lei
2019-12-18 10:49   ` Peter Zijlstra
2019-12-18 12:29     ` Peter Zijlstra
2019-12-19  1:59     ` Ming Lei
2019-12-19  9:23       ` Peter Zijlstra
2019-12-19  9:52         ` Ming Lei
2019-12-19 10:43         ` Daniel Wagner [this message]
2019-12-31  3:48           ` Ming Lei
2020-01-02 10:28             ` Daniel Wagner
2019-12-18  7:19 ` [RFC PATCH 3/3] blk-mq: complete request in rescuer process context in case of irq flood Ming Lei

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