From: "George Spelvin" <linux@horizon.com>
To: linux@horizon.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC 1/2] qrwlock: A queue read/write lock implementation
Date: 18 Jul 2013 09:18:24 -0400 [thread overview]
Message-ID: <20130718131824.10653.qmail@science.horizon.com> (raw)
In the interest of more useful Kconfig help, could I recommend the
following text:
config QUEUE_RWLOCK
bool "Generic queue read/write lock"
depends on ARCH_QUEUE_RWLOCK
help
Use an alternative reader-writer lock (rwlock) implementation,
optimized for larger NUMA systems. These locks use more memory,
but perform better under high contention. (Specifically, readers
waiting for a writer to release the lock will be queued rather
than all spinning on the same cache line.)
The kernel will operate correctly either way; this only
affects performance.
For common desktop and server systems systems with only one
or two CPU sockets, the performance benefits are not worth
the additional memory; say N here.
My goal is to give someone stumbling across this question for the first
time in "make oldconfig" the information htey need to answer it.
That said, I think Ingo's idea for simplfying the waiting reader side
is excellent and should be tried before bifurcating the implementation.
Looking at the lock system, it *seems* like that patch to __read_lock_failed
is literally the *only* thing that needs changing, since the write
lock/unlock is all done with relative add/sub anyway. But I keep thinking
"there must have been a reason why it wasn't done that way in the first
place".
next reply other threads:[~2013-07-18 13:18 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-18 13:18 George Spelvin [this message]
-- strict thread matches above, loose matches on Subject: below --
2013-07-18 12:55 [PATCH RFC 1/2] qrwlock: A queue read/write lock implementation George Spelvin
2013-07-18 13:43 ` Waiman Long
2013-07-18 18:46 ` George Spelvin
2013-07-19 15:43 ` Waiman Long
2013-07-19 21:11 ` George Spelvin
2013-07-19 21:35 ` Waiman Long
2013-07-13 1:34 [PATCH RFC 0/2] qrwlock: Introducing a " Waiman Long
2013-07-13 1:34 ` [PATCH RFC 1/2] qrwlock: A " Waiman Long
2013-07-13 1:34 ` Waiman Long
2013-07-15 14:39 ` Steven Rostedt
2013-07-15 14:39 ` Steven Rostedt
2013-07-15 20:44 ` Waiman Long
2013-07-15 20:44 ` Waiman Long
2013-07-15 22:31 ` Thomas Gleixner
2013-07-15 22:31 ` Thomas Gleixner
2013-07-16 1:19 ` Waiman Long
2013-07-16 1:19 ` Waiman Long
2013-07-18 7:42 ` Ingo Molnar
2013-07-18 7:42 ` Ingo Molnar
2013-07-18 7:42 ` Ingo Molnar
2013-07-18 13:40 ` Waiman Long
2013-07-18 13:40 ` Waiman Long
2013-07-18 13:40 ` Waiman Long
2013-07-19 8:40 ` Ingo Molnar
2013-07-19 8:40 ` Ingo Molnar
2013-07-19 8:40 ` Ingo Molnar
2013-07-19 15:30 ` Waiman Long
2013-07-19 15:30 ` Waiman Long
2013-07-19 15:30 ` Waiman Long
2013-07-22 10:34 ` Ingo Molnar
2013-07-22 10:34 ` Ingo Molnar
2013-07-22 10:34 ` Ingo Molnar
2013-07-24 0:03 ` Waiman Long
2013-07-24 0:03 ` Waiman Long
2013-07-24 0:03 ` Waiman Long
2013-07-18 10:22 ` Thomas Gleixner
2013-07-18 10:22 ` Thomas Gleixner
2013-07-18 14:19 ` Waiman Long
2013-07-18 14:19 ` Waiman Long
2013-07-21 5:42 ` Raghavendra K T
2013-07-21 5:42 ` Raghavendra K T
2013-07-21 5:42 ` Raghavendra K T
2013-07-23 23:54 ` Waiman Long
2013-07-23 23:54 ` Waiman Long
2013-07-23 23:54 ` Waiman Long
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