Re: [PATCH v2 -tip 0/6] locking: Introduce range reader/writer lock

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 -tip 0/6] locking: Introduce range reader/writer lock
Date	2017-04-19 14:40 +0200
Message-ID	<txX3Q-3sb-9@gated-at.bofh.it> (permalink)
References	<ttbh9-6aP-61@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Thu, Apr 06, 2017 at 01:46:14AM -0700, Davidlohr Bueso wrote:
> ** What's still pending:
>   - Debug support (it's been a pain to use lockdep with range locking).

How so? Just assume that every range is the full range. Which isn't such
a weird assumption as it would seem. After all, you cannot assume
anything much about the ranges to begin with. So therefore you cannot
assume the ranges don't all overlap either. At which point you're back
to the regular r/w semantics for deadlocks.

Also:

  - explain interval order and what that means for forward progress
    guarantees. This is currently still unparsable.

  - explain why the loss of lock stealing makes sense. IIRC walken added
    that specifically to address mmap_sem performance issues.

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Re: [PATCH v2 -tip 0/6] locking: Introduce range reader/writer lock Peter Zijlstra <peterz@infradead.org> - 2017-04-19 14:40 +0200
  Re: [PATCH v2 -tip 0/6] locking: Introduce range reader/writer lock Davidlohr Bueso <dave@stgolabs.net> - 2017-04-20 19:20 +0200
    Re: [PATCH v2 -tip 0/6] locking: Introduce range reader/writer lock Peter Zijlstra <peterz@infradead.org> - 2017-04-20 20:00 +0200
      Re: [PATCH v2 -tip 0/6] locking: Introduce range reader/writer lock Davidlohr Bueso <dave@stgolabs.net> - 2017-04-20 20:40 +0200
        Re: [PATCH v2 -tip 0/6] locking: Introduce range reader/writer lock Peter Zijlstra <peterz@infradead.org> - 2017-04-20 21:20 +0200

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