linux-kernel - Re: [PATCH v4 10/11] perf/x86/intel: Perform rotation on Intel CQM RMIDs

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]

Message-ID: <20150109121401.GB495@console-pimps.org>
Date:	Fri, 9 Jan 2015 12:14:01 +0000
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Ingo Molnar <mingo@...nel.org>, Jiri Olsa <jolsa@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Andi Kleen <andi@...stfloor.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>,
	Kanaka Juvva <kanaka.d.juvva@...el.com>,
	Matt Fleming <matt.fleming@...el.com>
Subject: Re: [PATCH v4 10/11] perf/x86/intel: Perform rotation on Intel CQM
 RMIDs

On Tue, 06 Jan, at 06:17:12PM, Peter Zijlstra wrote:
> 
> afaict the again label will try and steal yet another rmid, if rmids
> don't decay fast enough, we could end up with all rmids on the limbo
> list and none active. Or am I missing something here?

You're not missing anything, that's true, we will try and steal more
RMIDs. We could perhaps put a limit on how many RMIDs we're willing to
steal, but I think it should definitely be > 1 because RMIDs can
stabilize out of order.

It's worth pointing out that we only steal more RMIDs if the ones on the
limbo list have been queued for the "minimum queue time" - it really is
a last resort.

-- 
Matt Fleming, Intel Open Source Technology Center
--
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/