From: Peter Zijlstra <peterz@infradead.org>
To: Ming Lei <ming.lei@redhat.com>
Cc: 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>,
Keith Busch <keith.busch@intel.com>,
Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
John Garry <john.garry@huawei.com>,
Hannes Reinecke <hare@suse.com>
Subject: Re: [RFC PATCH 1/3] sched/core: add API for exporting runqueue clock
Date: Thu, 19 Dec 2019 10:20:26 +0100 [thread overview]
Message-ID: <20191219092026.GW2844@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20191219012914.GA6080@ming.t460p>
On Thu, Dec 19, 2019 at 09:29:14AM +0800, Ming Lei wrote:
> On Wed, Dec 18, 2019 at 10:51:01AM +0100, Peter Zijlstra wrote:
> > On Wed, Dec 18, 2019 at 03:19:40PM +0800, Ming Lei wrote:
> > > Scheduler runqueue maintains its own software clock that is periodically
> > > synchronised with hardware. Export this clock so that it can be used
> > > by interrupt flood detection for saving the cost of reading from hardware.
> >
> > But you don't have much, if any, guarantees the thing gets updated.
>
> Any software clock won't be guaranteed to be updated in time, however,
> they are still useful.
It still is broken, and I really don't want to expose this for whatever
reason.
next prev parent reply other threads:[~2019-12-19 9:21 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 [this message]
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
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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