Messages in this thread | | | Date | Tue, 21 Jan 2014 11:00:58 -0500 | From | Waiman Long <> | Subject | Re: [PATCH v9 2/5] qrwlock x86: Enable x86 to use queue read/write lock |
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On 01/20/2014 11:16 AM, Steven Rostedt wrote: > On Mon, 20 Jan 2014 17:08:06 +0100 > Peter Zijlstra<peterz@infradead.org> wrote: > >> On Tue, Jan 14, 2014 at 11:44:04PM -0500, Waiman Long wrote: >>> This patch makes the necessary changes at the x86 architecture specific >>> layer to enable the presence of the CONFIG_QUEUE_RWLOCK kernel option >>> to replace the read/write lock by the queue read/write lock. >>> >>> It also enables the CONFIG_QUEUE_RWLOCK option by default for x86 which >>> will force the use of queue read/write lock. That will greatly improve >>> the fairness of read/write lock and eliminate live-lock situation >>> where one task may not get the lock for an indefinite period of time. >>> >>> Signed-off-by: Waiman Long<Waiman.Long@hp.com> >>> Reviewed-by: Paul E. McKenney<paulmck@linux.vnet.ibm.com> >>> --- >>> arch/x86/Kconfig | 1 + >>> arch/x86/include/asm/spinlock.h | 2 ++ >>> arch/x86/include/asm/spinlock_types.h | 4 ++++ >>> 3 files changed, 7 insertions(+), 0 deletions(-) >> This patch doesn't have nearly enough -, you should rip out all traces >> of the old rwlock. There's no point in having it configurable, either >> qrwlock is good or not. > Although having something that switches back to the old method gives > more users the way to compare. Especially to catch any regressions. > > Make one release with it configurable, then drop it. > > -- Steve
Yes, I agree that it will be more prudent to leave the original rwlock implementation there for one or two release cycles before getting rid of them entirely.
-Longman
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