linux-kernel - Re: [PATCH 2/6] x86/platform/uv/BAU: Add status_mmr

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Date:   Thu, 16 Feb 2017 15:53:45 -0600
From:   Andrew Banman <abanman@....com>
To:     Thomas Gleixner <tglx@...utronix.de>
CC:     <mingo@...hat.com>, <akpm@...ux-foundation.org>, <hpa@...or.com>,
        <mike.travis@....com>, <rja@....com>, <sivanich@....com>,
        <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
        Andrew Banman <abanman@....com>
Subject: Re: [PATCH 2/6] x86/platform/uv/BAU: Add status_mmr_loc to locate
 message status bits



On 02/16/2017 12:07 PM, Thomas Gleixner wrote:
> On Tue, 14 Feb 2017, Andrew Banman wrote:
>
>> The location of the ERROR and BUSY status bits depends on the descriptor
>> index, i.e. the CPU, of the message. We determine this location ahead of
>> the wait_completion loop to avoid repeating the calculation.
>>
>> Split out the status location calculation into a new routine,
>> status_mmr_loc, to be used within each uv*_wait_completion routine.
>
> And the reason for this is? You just tell WHAT you are doing, not the WHY.
>
> Looking at the patch which implements the uv4 wait function it uses the
> thing as well. So for the casual reader there is no point.
>
> The only reason i figured why you want to do that is to reduce the number
> of arguments to the wait function, correct?
>
> If yes, then spell it out. If no, please enlighten me.

Yes, the purpose was to re-scope the mmr location-finding logic into the 
uv*_wait_completion routines to make the call to wait_completion less 
complicated.

Though, on second thought, the *mmr and *index values in status_mmr_loc 
should really be set during initialization because they do not change. 
The calculation is always done with desc=uvhub_cpu.

I would add status_mmr and status_index to struct bau_control and move 
the calculation to scan_sock; there's no need for a subroutine in this case.

Thanks,

Andrew Banman

>
> Thanks,
>
> 	tglx
>