On Thu, 20 Apr 2017, Peter Zijlstra wrote:
For opt spinning we need to specifically know who would be next in
order, again, doesn't matter how many, just who's next.
I've sent a v3 with a more precise description of this, which I hope is
to your satisfaction.
Given a clear tree iteration/orde
On Thu, Apr 20, 2017 at 11:36:46AM -0700, Davidlohr Bueso wrote:
> On Thu, 20 Apr 2017, Peter Zijlstra wrote:
> >Those are about avoiding actually going to sleep and having to be woken
> >up (and waiting to become running) again, which is a long time.
>
> Yes, which is why I was thinking of ways t
On Thu, 20 Apr 2017, Peter Zijlstra wrote:
On Thu, Apr 20, 2017 at 10:13:26AM -0700, Davidlohr Bueso wrote:
I have thought of some heuristics for avoiding sleeping under certain
constraints, which could mitigate the spinning step we loose, but I fear it
will never be exactly as fast as rwsems
On Thu, Apr 20, 2017 at 10:13:26AM -0700, Davidlohr Bueso wrote:
> I have thought of some heuristics for avoiding sleeping under certain
> constraints, which could mitigate the spinning step we loose, but I fear it
> will never be exactly as fast as rwsems -- just consider
> we always take the tre
On Wed, 19 Apr 2017, Peter Zijlstra wrote:
- explain why the loss of lock stealing makes sense. IIRC walken added
that specifically to address mmap_sem performance issues.
That's right, and the same applies to the writer spinning stuff; which
can makes a huge difference - more so than plai
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
Changes from v1 (https://lwn.net/Articles/716383/), all in patch 2:
- s/EXPORT_SYMBOL/EXPORT_SYMBOL_GPL
- Made the tree walks a foreach loop, instead of while.
- Fixed signal_pending() lockup issue for unaccounted waiters.
- Fixed initialization macros.
- Check condition before signal_pen
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