From: Peter Zijlstra <peterz@infradead.org>
To: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Cc: lkml <linux-kernel@vger.kernel.org>, arc-linux-dev@synopsys.com
Subject: Re: [PATCH 6/6] ARCv2: spinlock/rwlock: Reset retry delay when starting a new spin-wait cycle
Date: Mon, 3 Aug 2015 13:43:52 +0200 [thread overview]
Message-ID: <20150803114352.GL25159@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1438596188-10875-7-git-send-email-vgupta@synopsys.com>
On Mon, Aug 03, 2015 at 03:33:08PM +0530, Vineet Gupta wrote:
> A spin lock could be available momentarily, but the SCOND to actually
> acquire it might still fail due to concurrent update from other core(s).
> To elide hardware lock, the sequence is retried after a "delay" which is
> increased expoenntially to get a nice backoff behaviour.
>
> However, this could cause the delay counter to get to a high value. Thus
> when the next spin cycle restarts, reset the counter back to starting
> value of 1.
Cute.. fwiw, did you look at what Sparc64 does?
next prev parent reply other threads:[~2015-08-03 11:43 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-03 10:03 [PATCH 0/6] ARC: spinlocks/atomics rework Vineet Gupta
2015-08-03 10:03 ` [PATCH 1/6] Revert "ARCv2: STAR 9000837815 workaround hardware exclusive transactions livelock" Vineet Gupta
2015-08-03 10:03 ` [PATCH 2/6] ARC: refactor atomic inline asm operands with symbolic names Vineet Gupta
2015-08-03 10:03 ` [PATCH 3/6] ARC: LLOCK/SCOND based spin_lock Vineet Gupta
2015-08-03 11:29 ` Peter Zijlstra
2015-08-03 11:44 ` Vineet Gupta
2015-08-03 10:03 ` [PATCH 4/6] ARC: LLOCK/SCOND based rwlock Vineet Gupta
2015-08-03 11:33 ` Peter Zijlstra
2015-08-03 11:51 ` Vineet Gupta
2015-08-03 10:03 ` [PATCH 5/6] ARCv2: spinlock/rwlock/atomics: Delayed retry of failed SCOND with exponential backoff Vineet Gupta
2015-08-03 11:41 ` Peter Zijlstra
2015-08-03 13:01 ` Vineet Gupta
2015-08-03 13:50 ` Vineet Gupta
2015-08-03 14:08 ` Peter Zijlstra
2015-08-03 11:50 ` Peter Zijlstra
2015-08-03 13:02 ` Vineet Gupta
2015-08-03 13:06 ` Peter Zijlstra
2015-08-03 10:03 ` [PATCH 6/6] ARCv2: spinlock/rwlock: Reset retry delay when starting a new spin-wait cycle Vineet Gupta
2015-08-03 11:43 ` Peter Zijlstra [this message]
2015-08-03 14:40 ` Vineet Gupta
2015-08-03 14:42 ` Peter Zijlstra
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