From: Waiman Long <Waiman.Long@hp.com>
To: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
Scott J Norton <scott.norton@hp.com>,
Douglas Hatch <doug.hatch@hp.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Waiman Long <Waiman.Long@hp.com>
Subject: [PATCH 0/6 v2] locking/qspinlock: Enhance pvqspinlock performance
Date: Tue, 14 Jul 2015 22:13:31 -0400 [thread overview]
Message-ID: <1436926417-20256-1-git-send-email-Waiman.Long@hp.com> (raw)
v1->v2:
- Take out the queued unfair lock patches
- Add a patch to simplify the PV unlock code
- Move pending bit and statistics collection patches to the front
- Keep vCPU kicking in pv_kick_node(), but defer it to unlock time
when appropriate.
- Change the wait-early patch to use adaptive spinning to better
balance the difference effect on normal and over-committed guests.
- Add patch-to-patch performance changes in the patch commit logs.
This patchset tries to improve the performance of both normal and
over-commmitted VM guests. The kick-ahead and adaptive spinning
patches are inspired by the "Do Virtual Machines Really Scale?" blog
from Sanidhya Kashyap.
Patch 1 simplifies the unlock code by doing unconditional vCPU kick
when _Q_SLOW_VAL is set as the chance of spurious wakeup showing
up in the statistical data that I collected was very low (1 or 2
occasionally).
Patch 2 adds pending bit support to pvqspinlock improving performance
at light load.
Patch 3 allows the collection of various count data that are useful
to see what is happening in the system. They do add a bit of overhead
when enabled. This will slow the system a little bit.
Patch 4 enables multiple vCPU kicks at unlock time, outside of the
critical section. Coupled with patch 5 which defers kicking to unlock
time, this will improve system performance in overcommitted guests
and sometime even in normal guests.
Patch 6 enables adaptive spinning in the queue nodes. This patch can lead
to pretty big performance increase in over-committed guest at the expense
of a slight performance hit in normal guests.
Waiman Long (6):
locking/pvqspinlock: Unconditional PV kick with _Q_SLOW_VAL
locking/pvqspinlock: Add pending bit support
locking/pvqspinlock: Collect slowpath lock statistics
locking/pvqspinlock: Allow vCPUs kick-ahead
locking/pvqspinlock: Opportunistically defer kicking to unlock time
locking/pvqspinlock: Queue node adaptive spinning
arch/x86/Kconfig | 7 +
kernel/locking/qspinlock.c | 38 +++-
kernel/locking/qspinlock_paravirt.h | 452 +++++++++++++++++++++++++++++++++--
3 files changed, 473 insertions(+), 24 deletions(-)
next reply other threads:[~2015-07-15 2:13 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-15 2:13 Waiman Long [this message]
2015-07-15 2:13 ` [PATCH v2 1/6] locking/pvqspinlock: Unconditional PV kick with _Q_SLOW_VAL Waiman Long
2015-07-15 9:10 ` Peter Zijlstra
2015-07-16 0:18 ` Waiman Long
2015-07-16 5:42 ` Peter Zijlstra
2015-07-16 14:07 ` Waiman Long
2015-07-16 15:04 ` Waiman Long
2015-07-16 15:10 ` Will Deacon
2015-08-03 16:59 ` [tip:locking/core] locking/Documentation: Clarify failed cmpxchg( ) memory ordering semantics tip-bot for Will Deacon
2015-08-03 17:36 ` Davidlohr Bueso
2015-07-15 2:13 ` [PATCH v2 2/6] locking/pvqspinlock: Add pending bit support Waiman Long
2015-07-15 2:13 ` [PATCH v2 3/6] locking/pvqspinlock: Collect slowpath lock statistics Waiman Long
2015-07-15 2:13 ` [PATCH v2 4/6] locking/pvqspinlock: Allow vCPUs kick-ahead Waiman Long
2015-07-15 9:39 ` Peter Zijlstra
2015-07-16 2:01 ` Waiman Long
2015-07-16 5:46 ` Peter Zijlstra
2015-07-16 14:51 ` Waiman Long
2015-07-15 2:13 ` [PATCH v2 5/6] locking/pvqspinlock: Opportunistically defer kicking to unlock time Waiman Long
2015-07-15 6:14 ` Raghavendra K T
2015-07-15 10:03 ` Peter Zijlstra
2015-07-16 2:18 ` Waiman Long
2015-07-16 5:49 ` Peter Zijlstra
2015-07-15 2:13 ` [PATCH v2 6/6] locking/pvqspinlock: Queue node adaptive spinning Waiman Long
2015-07-15 10:01 ` Peter Zijlstra
2015-07-16 2:13 ` Waiman Long
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