linux-kernel - Re: [patch 1/4] x86: FIFO ticket spinlocks

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:	Sat, 3 Nov 2007 04:41:46 +0100
From:	Nick Piggin <npiggin@...e.de>
To:	Chuck Ebbert <cebbert@...hat.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andi Kleen <ak@...e.de>, Ingo Molnar <mingo@...e.hu>
Subject: Re: [patch 1/4] x86: FIFO ticket spinlocks

On Fri, Nov 02, 2007 at 08:56:46PM -0400, Chuck Ebbert wrote:
> On 11/02/2007 07:01 PM, Nick Piggin wrote:
> > 
> > In the contended multi-threaded tight loop, the xchg lock is slower than inc
> > lock but still beats the fair xadd lock, but that's only because it is
> > just as unfair if not more so on this hardware (runtime difference of up to
> > about 10%)
> > 
> 
> I meant xchg for unlock, not lock.

That is for unlock. 2x the number of atomic operations ~= 2x the cost.

-
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/