Message-ID: <520BAE58.3060600@arm.com>
Date: Wed, 14 Aug 2013 17:20:40 +0100
From: Jonathan Austin <jonathan.austin@arm.com>
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CC: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Will Deacon <Will.Deacon@arm.com>
Subject: Re: arm: Only load TLS values when needed
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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

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