From: Peter Zijlstra <peterz@infradead.org>
To: Davidlohr Bueso <dave@stgolabs.net>
Cc: mingo@kernel.org, akpm@linux-foundation.org, jack@suse.cz,
kirill.shutemov@linux.intel.com, ldufour@linux.vnet.ibm.com,
mhocko@suse.com, mgorman@techsingularity.net,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 -tip 0/6] locking: Introduce range reader/writer lock
Date: Thu, 20 Apr 2017 19:53:50 +0200 [thread overview]
Message-ID: <20170420175350.44mvhizyulyzb6oc@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20170420171326.GD20746@linux-80c1.suse>
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 tree->lock.
But tree->lock is a spinlock, so while this gets us out of rwsem-xadd
territory for the fast paths, the whole lock-stealing and optimistic
spinning stuff is on a different scale.
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.
next prev parent reply other threads:[~2017-04-20 17:54 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-06 8:46 [PATCH v2 -tip 0/6] locking: Introduce range reader/writer lock Davidlohr Bueso
2017-04-06 8:46 ` [PATCH 1/6] interval-tree: Build unconditionally Davidlohr Bueso
2017-04-06 8:46 ` [PATCH 2/6] locking: Introduce range reader/writer lock Davidlohr Bueso
2017-04-06 9:01 ` Laurent Dufour
2017-04-06 16:50 ` Davidlohr Bueso
2017-04-13 8:07 ` Laurent Dufour
2017-04-13 8:38 ` Jan Kara
2017-04-13 8:58 ` Laurent Dufour
2017-04-06 10:24 ` Peter Zijlstra
2017-04-18 13:57 ` Laurent Dufour
2017-04-20 16:01 ` Davidlohr Bueso
2017-04-21 7:00 ` Laurent Dufour
2017-04-06 8:46 ` [PATCH 3/6] locking/locktorture: Fix rwsem reader_delay Davidlohr Bueso
2017-04-06 8:46 ` [PATCH 4/6] locking/locktorture: Fix num reader/writer corner cases Davidlohr Bueso
2017-04-06 8:46 ` [PATCH 5/6] locking/locktorture: Support range rwlocks Davidlohr Bueso
2017-04-06 8:46 ` [PATCH 6/6] staging/lustre: Use generic range rwlock Davidlohr Bueso
2017-04-07 10:08 ` Dilger, Andreas
2017-04-07 10:08 ` [lustre-devel] " Dilger, Andreas
2017-04-19 12:37 ` [PATCH v2 -tip 0/6] locking: Introduce range reader/writer lock Peter Zijlstra
2017-04-20 17:13 ` Davidlohr Bueso
2017-04-20 17:53 ` Peter Zijlstra [this message]
2017-04-20 18:36 ` Davidlohr Bueso
2017-04-20 19:10 ` Peter Zijlstra
2017-05-15 9:19 ` Davidlohr Bueso
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