linux-kernel - Re: [PATCH] x86: X86_HT always enable on X86

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Date:	Wed, 27 Feb 2008 14:31:21 -0800
From:	Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
To:	Yinghai Lu <yhlu.kernel@...il.com>
Cc:	"H. Peter Anvin" <hpa@...or.com>, Adrian Bunk <bunk@...nel.org>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Sam Ravnborg <sam@...nborg.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: X86_HT always enable on X86_64 SMP

Yinghai Lu wrote:
> On Wed, Feb 27, 2008 at 1:30 PM, H. Peter Anvin <hpa@...or.com> wrote:
>> Adrian Bunk wrote:
>>  > On Wed, Feb 27, 2008 at 01:16:30PM -0800, Hiroshi Shimamoto wrote:
>>  >> From: Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
>>  >>
>>  >> X86_HT is used for hyperthreading or multicore on 32-bit.
>>  >> The X86_HT on 64-bit is different from 32-bit, it means hyperthreading only.
>>  >> And X86_HT is not used on 64-bit except from cpu/initel_cacheinfo.c.
>>  >>
>>  >> Unify X86_HT for hyperthreading or multicore.
>>  >> Turn X86_HT on when X86_64 and SMP are enabled.
>>  >
>>  > Please fix it properly instead - fiddling around with it the way you do
>>  > only asks for trouble in the future.
>>  >
>>  > What we need are two different variables for:
>>  > - hyperthreading and
>>  > - multicore
>>  >
>>
>>  He does, and calls them SCHED_SMT and SCHED_MC respectively.
>>
>>  It's not particularly clear to me what X86_HT is meant to be used for
>>  anymore at all.
> 
> he made X86_HT can be enabled when only Opteron supported is enabled.

yes on 64-bit. On 32-bit MK8 doesn't affect X86_HT.

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