linux-kernel - Re: [PATCH 1/1] Bumps limit of maximum core ID from 32 to 128.

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Message-ID: <561D8514.2040503@roeck-us.net>
Date:	Tue, 13 Oct 2015 15:26:28 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	"Odzioba, Lukasz" <lukasz.odzioba@...el.com>
Cc:	"Yu, Fenghua" <fenghua.yu@...el.com>,
	"jdelvare@...e.de" <jdelvare@...e.de>,
	"lm-sensors@...sensors.org" <lm-sensors@...sensors.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Phil Pokorny <ppokorny@...guincomputing.com>
Subject: Re: [PATCH 1/1] Bumps limit of maximum core ID from 32 to 128.

On 10/13/2015 03:02 PM, Odzioba, Lukasz wrote:
> On Tuesday, October 12, 2015 at 10:32 PM, Guenter Roeck wrote:
>> Why 128 instead of a more reasonable 64 ? What is the required minimum
>> for Xeon Phi ?
>
> It would be fine today, but it will be not enough in 2016 and we would like to
> give GNU/Linux distributions some time to propagate this patch.
> For Knights Corner which is already on the market we need 61.
> For Knights Landing we need 72.

Pardon my ignorance ... those are Xeon Phi processors, and support up to
244 threads (for Knights Corner). Programming datasheet isn't easily available,
so I have to guess a bit. Following the processor numbering scheme of "ordinary"
processors, the CPU ID can therefore be up to 244 (at least) already today,
meaning the limit would have to be 256 (assuming that the processor does support
per-core temperature sensors). On the other side, the public datasheet suggests
that there are only three temperature sensors.

What am I missing here ?

Thanks,
Guenter

> For future generation it is not yet public information.
>
>> Also, please consider using the subject line commonly used in hwmon,
>> or at least point to the driver you are changing.
>
> Right, I forgot this time, I'll send another patch just tell me whether 128
> is ok, or please select any other value greater or equal known minimum
> that you think will be more appropriate.
>
> Thanks,
> Lukas
>
>
>

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