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From: Waiman Long <longman@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>
Cc: linux-kernel@vger.kernel.org, Bart Van Assche <bvanassche@acm.org>
Subject: Re: [PATCH v2 0/6] locking/lockdep: Reuse zapped chain_hlocks entries
Date: Mon, 6 Jan 2020 10:54:24 -0500	[thread overview]
Message-ID: <dfcfc267-1a2f-8070-c08b-662e9fe4798c@redhat.com> (raw)
In-Reply-To: <20191216151517.7060-1-longman@redhat.com>

On 12/16/19 10:15 AM, Waiman Long wrote:
>  v2:
>   - Revamp the chain_hlocks reuse patch to store the freed chain_hlocks
>     information in the chain_hlocks entries themselves avoiding the
>     need of a separate set of tracking structures. This, however,
>     requires a minimum allocation size of at least 2. Thanks to PeterZ
>     for his review and inspiring this change.
>   - Remove the leakage counter as it is no longer applicable.
>   - Add patch 6 to make the output of /proc/lockdep_chains more readable.
>
> It was found that when running a workload that kept on adding lock
> classes and then zapping them repetitively, the system will eventually
> run out of chain_hlocks[] entries even though there were still plenty
> of other lockdep data buffers available.
>
>   [ 4318.443670] BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!
>   [ 4318.444809] turning off the locking correctness validator.
>
> In order to fix this problem, we have to make chain_hlocks[] entries
> reusable just like other lockdep arrays. Besides that, the patchset
> also adds some zapped class and chain_hlocks counters to be tracked by
> /proc/lockdep_stats. It also fixes leakage in the irq context counters
> and makes the output of /proc/lockdep_chains more readable.
>
> Waiman Long (6):
>   locking/lockdep: Track number of zapped classes
>   locking/lockdep: Throw away all lock chains with zapped class
>   locking/lockdep: Track number of zapped lock chains
>   locking/lockdep: Reuse freed chain_hlocks entries
>   locking/lockdep: Decrement irq context counters when removing lock
>     chain
>   locking/lockdep: Display irq_context names in /proc/lockdep_chains
>
>  kernel/locking/lockdep.c           | 307 +++++++++++++++++++++++------
>  kernel/locking/lockdep_internals.h |  14 +-
>  kernel/locking/lockdep_proc.c      |  26 ++-
>  3 files changed, 282 insertions(+), 65 deletions(-)
>
Ping! Any comments or suggestion for further improvement?

Cheers,
Longman


  parent reply	other threads:[~2020-01-06 15:54 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-16 15:15 [PATCH v2 0/6] locking/lockdep: Reuse zapped chain_hlocks entries Waiman Long
2019-12-16 15:15 ` [PATCH v2 1/6] locking/lockdep: Track number of zapped classes Waiman Long
2020-01-13 14:55   ` Peter Zijlstra
2020-01-13 14:58     ` Waiman Long
2020-01-13 16:02       ` Bart Van Assche
2019-12-16 15:15 ` [PATCH v2 2/6] locking/lockdep: Throw away all lock chains with zapped class Waiman Long
2020-01-13 15:18   ` Peter Zijlstra
2020-01-13 15:44     ` Waiman Long
2020-01-13 16:05     ` Bart Van Assche
2020-01-13 16:15       ` Waiman Long
2019-12-16 15:15 ` [PATCH v2 3/6] locking/lockdep: Track number of zapped lock chains Waiman Long
2019-12-16 15:15 ` [PATCH v2 4/6] locking/lockdep: Reuse freed chain_hlocks entries Waiman Long
2020-01-13 15:51   ` Peter Zijlstra
2020-01-13 16:04     ` Waiman Long
2020-01-13 15:58   ` Peter Zijlstra
2020-01-13 16:24     ` Waiman Long
2020-01-14  9:46       ` Peter Zijlstra
2020-01-14 19:16         ` Waiman Long
2020-01-15 10:44           ` Peter Zijlstra
2020-01-15 19:26             ` Waiman Long
2020-01-13 15:59   ` Peter Zijlstra
2020-01-13 16:03     ` Waiman Long
2019-12-16 15:15 ` [PATCH v2 5/6] locking/lockdep: Decrement irq context counters when removing lock chain Waiman Long
2020-01-14  9:53   ` Peter Zijlstra
2020-01-14 15:04     ` Waiman Long
2019-12-16 15:15 ` [PATCH v2 6/6] locking/lockdep: Display irq_context names in /proc/lockdep_chains Waiman Long
2020-01-06 15:54 ` Waiman Long [this message]
2020-01-06 16:50   ` [PATCH v2 0/6] locking/lockdep: Reuse zapped chain_hlocks entries Peter Zijlstra
2020-01-06 16:52     ` Waiman Long

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