From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Hillf Danton <hdanton@sina.com>
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: Fri, 20 Jan 2023 19:34:02 +0100 [thread overview]
Message-ID: <Y8remhZnLCtr+y5s@linutronix.de> (raw)
In-Reply-To: <20230120093711.3862-1-hdanton@sina.com>
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.
So it is basically the same scenario.
Sebastian
next prev parent reply other threads:[~2023-01-20 18:34 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 [this message]
2023-01-21 3:46 ` Hillf Danton
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