Message-ID: <4FBE4E05.7070603@zytor.com>
Date: Thu, 24 May 2012 08:04:37 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Alex Shi <alex.shi@intel.com>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>, Jan Beulich <JBeulich@suse.com>,
        borislav.petkov@amd.com, arnd@arndb.de, akinobu.mita@gmail.com,
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        hughd@google.com, jeremy@goop.org, len.brown@intel.com,
        tony.luck@intel.com, yongjie.ren@intel.com,
        kamezawa.hiroyu@jp.fujitsu.com, seto.hidetoshi@jp.fujitsu.com,
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Subject: Re: [PATCH v7 8/8] x86/tlb: just do tlb flush on one of siblings
 of SMT
References: <1337782555-8088-1-git-send-email-alex.shi@intel.com>  <1337782555-8088-9-git-send-email-alex.shi@intel.com>  <4FBD18D20200007800085951@nat28.tlf.novell.com> <1337792984.9783.37.camel@laptop> <4FBDF200.7060608@intel.com>
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On 05/24/2012 01:32 AM, Alex Shi wrote:
> 
> Sure. but just want to know how many commercial x86 CPU uses >2 SMTs?
> Write a short, quick function to do random selection in SMT is quite
> complicate considering cpumask maybe just contain random number SMT
> siblings in a core.
> 

Wrong question.  This is a forward compatibility issue.  You have to
take into account potential future CPUs as well.

And no, it isn't hard.

	-hpa

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