linux-kernel - Re: [PATCH v7 8/8] x86/tlb: just do tlb flush on one of siblings of SMT

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 24 May 2012 08:04:37 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Alex Shi <alex.shi@...el.com>
CC:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Jan Beulich <JBeulich@...e.com>, borislav.petkov@....com,
	arnd@...db.de, akinobu.mita@...il.com, eric.dumazet@...il.com,
	fweisbec@...il.com, rostedt@...dmis.org, hughd@...gle.com,
	jeremy@...p.org, len.brown@...el.com, tony.luck@...el.com,
	yongjie.ren@...el.com, kamezawa.hiroyu@...fujitsu.com,
	seto.hidetoshi@...fujitsu.com, penberg@...nel.org,
	yinghai@...nel.org, tglx@...utronix.de, akpm@...ux-foundation.org,
	ak@...ux.intel.com, luto@....edu, avi@...hat.com,
	dhowells@...hat.com, mingo@...hat.com, riel@...hat.com,
	cpw@....com, steiner@....com, linux-kernel@...r.kernel.org,
	viro@...iv.linux.org.uk
Subject: Re: [PATCH v7 8/8] x86/tlb: just do tlb flush on one of siblings
 of SMT

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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/