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Message-ID: <20151117112343.GW3816@twins.programming.kicks-ass.net> Date: Tue, 17 Nov 2015 12:23:43 +0100 From: Peter Zijlstra <peterz@...radead.org> To: Vineet Gupta <Vineet.Gupta1@...opsys.com> Cc: Noam Camus <noamc@...hip.com>, linux-snps-arc@...ts.infradead.org, linux-kernel@...r.kernel.org, talz@...hip.com, gilf@...hip.com, cmetcalf@...hip.com Subject: Re: [PATCH v2 18/19] ARC: [plat-eznps] replace sync with proper cpu barrier On Tue, Nov 17, 2015 at 04:42:49PM +0530, Vineet Gupta wrote: > On Saturday 07 November 2015 04:22 PM, Noam Camus wrote: > > From: Tal Zilcer <talz@...hip.com> > > > > In SMT system like we have the generic "sync" is not working with > > HW threads. The replacement is "schd.rw" instruction that is served > > as cpu barrier for HW threads. > > As discussed in v2 of this patch, SYNC or some such in __switch_to is completely > superfluous. We don't need this patch, you may instead wanna submit a patch which > removes the sync. Also please do that in assembler version of this file as well ! Do test it though; as is ARC-SMP seems to have a _lot_ of superfluous barriers many of which have no explanation yet (I'm thinking of those extra smp_mb()s in the lock primitives). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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