linux-kernel - Re: [PATCH] raise tsc clocksource rating

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: <20071029230213.GA1982@elte.hu>
Date:	Tue, 30 Oct 2007 00:02:13 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Zachary Amsden <zach@...are.com>
Cc:	Glauber de Oliveira Costa <gcosta@...hat.com>,
	linux-kernel@...r.kernel.org, tglx@...utronix.de,
	rusty@...tcorp.com.au, jeremy@...p.org, --cc@...hat.com,
	avi@...amnet.com, kvm-devel@...ts.sourceforge.net,
	Glauber de Oliveira Costa <glauber@....localdomain>,
	Dan Hecht <dhecht@...are.com>,
	Garrett Smith <garrett@...are.com>
Subject: Re: [PATCH] raise tsc clocksource rating


* Zachary Amsden <zach@...are.com> wrote:

> On Mon, 2007-10-29 at 23:48 +0100, Ingo Molnar wrote:
> > * Zachary Amsden <zach@...are.com> wrote:
> 
> > if it's inaccurate why are you exposing it to the guest then? Native 
> > only uses the TSC if it's safe and accurate to do so.
> 
> Not every guest support paravirt, but for correctness, all guests 
> require TSC, which must be exposed all the way up to userspace, no 
> matter what the efficiency or accuracy may be.

but if there's a perfect TSC available (there is such hardware) then the 
TSC _is_ the best clocksource. Paravirt now turns it off unconditionally 
in essence.

anyway, that's at most an optimization issue. No strong feelings here, 
and we can certainly delay this patch until this gets all sorted out.

	Ingo
-
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/