From: Hillf Danton <hdanton@sina.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Mel Gorman <mgorman@techsingularity.net>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
Davidlohr Bueso <dave@stgolabs.net>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] locking/rwbase: Prevent indefinite writer starvation
Date: Sat, 21 Jan 2023 11:46:54 +0800 [thread overview]
Message-ID: <20230121034654.3958-1-hdanton@sina.com> (raw)
In-Reply-To: <Y8remhZnLCtr+y5s@linutronix.de>
On Fri, 20 Jan 2023 19:34:02 +0100 Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> On 2023-01-20 17:37:11 [+0800], Hillf Danton wrote:
> >
> > I am fine with either 4ms or 40ms, or a second.
> >
> > Given the cure, does it still work when reader bias for RT tasks is allowed?
> No.
>
> > If not, why keep starving waiters after they pay the 40ms price?
>
> That kind of starvation will also happen if you have only spinlock_t
> locks and you say 3 RT tasks that acquire the lock back to back. And a
> few SCHED_OTHER tasks. Those 3 will be always be in front of the queue
> (as they skip the line) and the following SCHED_OTHER tasks will starve
> and never get the lock.
Given priority, what sense could be made by keeping RT task starved?
prev parent reply other threads:[~2023-01-21 3:47 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20230117083817.togfwc5cy4g67e5r@techsingularity.net>
[not found] ` <Y8avJm1FQI9vB9cv@linutronix.de>
[not found] ` <20230117165021.t5m7c2d6frbbfzig@techsingularity.net>
[not found] ` <Y8gPhTGkfCbGwoUu@linutronix.de>
[not found] ` <20230118173130.4n2b3cs4pxiqnqd3@techsingularity.net>
2023-01-19 1:15 ` Hillf Danton
2023-01-19 8:32 ` Sebastian Andrzej Siewior
2023-01-19 13:59 ` Hillf Danton
2023-01-19 16:36 ` Sebastian Andrzej Siewior
2023-01-20 9:37 ` Hillf Danton
2023-01-20 18:34 ` Sebastian Andrzej Siewior
2023-01-21 3:46 ` Hillf Danton [this message]
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