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:	Wed, 23 May 2012 18:46:58 -0700
From:	Andrew Lutomirski <luto@....edu>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Jan Beulich <JBeulich@...e.com>, Alex Shi <alex.shi@...el.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, 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, hpa@...or.com
Subject: Re: [PATCH v7 8/8] x86/tlb: just do tlb flush on one of siblings of SMT

On Wed, May 23, 2012 at 10:15 AM, Peter Zijlstra <peterz@...radead.org> wrote:
> On Wed, 2012-05-23 at 19:09 +0200, Peter Zijlstra wrote:
>> > There is no comment or anything else indicating that this is
>> > suitable for dual-thread CPUs only - when there are more than
>> > 2 threads per core, the intended effect won't be achieved.
>>
>> Why would that be? Won't higher thread count still share the same
>> resources just more so?
>
> Ah, I see, you're saying his code is buggy for >2 threads. Agreed.
>

An evil knob to statically choose which SMT sibling gets the interrupt
would be nice.  Then my compute-intensive thread could be (mostly)
unaffected by the other thread on a different core that calls munmap
frequently.

--Andy
--
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/