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Message-ID: <520BAE58.3060600@arm.com> Date: Wed, 14 Aug 2013 17:20:40 +0100 From: Jonathan Austin <jonathan.austin@....com> To: André Hentschel <nerv@...ncrow.de> CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Will Deacon <Will.Deacon@....com> Subject: Re: arm: Only load TLS values when needed Hi André, On 14/08/13 15:07, André Hentschel wrote: > Hi Jonathan, > Any updates on this? > I was holding out to see the version with ldrd at the top, as discussed below - I never saw a version with that change? I'd meant to ping you to see if that was coming, sorry. [...] >>> [...] >>>>> Now we've only got one instruction between the store and the load >>>>> and risk stalling the pipeline... >>>>> >>>>> Dave M cautiously says "The ancient advice was that one instruction >>>>> was enough" but this is very core dependent... I wonder if anyone >>>>> has a good idea about whether this is an issue here...? >>>> >>>> We could use a ldrd at the top, that'd be nearly what we have right >>>> now, don't we? >>> >>> Yea, that'd be good - as far as I can see from an 1136 TRM, the ldrd *may* be two cycles (depending on alignment of the words) but the ldr and ldrne will always be two cycles. Ahhh, the joys of modifying the fast path ;) Was expecting to see something that reflected this discussion, Jonny -- 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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