linux-kernel - Re: [PATCH 2/4, v2] x86: enlightenment for ticket spin locks

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, 30 Jun 2010 15:03:34 +0100
From:	"Jan Beulich" <JBeulich@...ell.com>
To:	"Jeremy Fitzhardinge" <jeremy@...p.org>
Cc:	"mingo@...e.hu" <mingo@...e.hu>,
	"Stefano Stabellini" <stefano.stabellini@...citrix.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"Ky Srinivasan" <KSrinivasan@...ell.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"hpa@...or.com" <hpa@...or.com>
Subject: Re: [PATCH 2/4, v2] x86: enlightenment for ticket spin locks -
	 Xen implementation

>>> On 30.06.10 at 15:23, Jeremy Fitzhardinge <jeremy@...p.org> wrote:
> For spinlocks, the pvop calls should only be in the slow case: when a
> spinlock has been spinning for long enough, and on unlock when there's
> someone waiting for the lock.  The fastpath (no contention lock and
> unlock) should have no extra calls.

Then what was all that performance regression noise concerning
pvops spinlocks about, leading to CONFIG_PARAVIRT_SPINLOCKS
being separated from the base CONFIG_PARAVIRT?

Afaics the unlock still involves a function call *in all cases* with
pvops spinlocks, whereas it's a single inline instruction without.

Jan

--
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/