linux-kernel - [PATCH 0/2] locking/percpu-rwsem: Optimizations/tweaks

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Message-Id: <20160714182545.786693675@infradead.org>
Date:	Thu, 14 Jul 2016 20:25:45 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	mingo@...nel.org, linux-kernel@...r.kernel.org
Cc:	oleg@...hat.com, tj@...nel.org, paulmck@...ux.vnet.ibm.com,
	john.stultz@...aro.org, dimitrysh@...gle.com, romlem@...gle.com,
	ccross@...gle.com, tkjos@...gle.com, peterz@...radead.org
Subject: [PATCH 0/2] locking/percpu-rwsem: Optimizations/tweaks

As reported by John and Dmitry, Android tickles bad behaviour in
cgroup_threadgroup_rwsem.

These two patches attempt to address the issue by optimizing the percpu-rwsem
slow path and second add a bias knob to the percpu-rwsem that allows disabling
the fast path which improves writer latency by getting rid of a
synchronize_sched() call.

---
 fs/super.c                    |   3 +-
 include/linux/percpu-rwsem.h  |  96 +++++++++++++++--
 kernel/cgroup.c               |   2 +-
 kernel/locking/percpu-rwsem.c | 246 +++++++++++++++++++++++++-----------------
 4 files changed, 239 insertions(+), 108 deletions(-)