linux-kernel - Re: [GIT PULL] adaptive spinning mutexes

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:	Thu, 15 Jan 2009 10:44:40 -0700
From:	Matthew Wilcox <matthew@....cx>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Gregory Haskins <ghaskins@...ell.com>,
	Andi Kleen <andi@...stfloor.org>,
	Chris Mason <chris.mason@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	linux-btrfs <linux-btrfs@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Nick Piggin <npiggin@...e.de>,
	Peter Morreale <pmorreale@...ell.com>,
	Sven Dietrich <SDietrich@...ell.com>,
	Dmitry Adamushko <dmitry.adamushko@...il.com>,
	Johannes Weiner <hannes@...xchg.org>
Subject: Re: [GIT PULL] adaptive spinning mutexes

On Wed, Jan 14, 2009 at 08:28:11PM +0100, Ingo Molnar wrote:
>                       [v2.6.14]     [v2.6.29]
> 
>                       Semaphores  | Mutexes
>             ----------------------------------------------
>                                   | no-spin           spin
>                                   |
>   [tmpfs]   ops/sec:       50713  |  291038         392865       (+34.9%)
>   [ext3]    ops/sec:       45214  |  283291         435674       (+53.7%)
> 
> A 10x macro-performance improvement on ext3, compared to 2.6.14 :-)
> 
> While lots of other details got changed meanwhile, i'm sure most of the 
> performance win on this particular VFS workload comes from mutexes.

I asked a couple of our benchmarking teams to try -v9.  Neither the OLTP
benchmark, nor the kernel-perf test suite found any significant
performance change.  I suspect mutex contention isn't a significant
problem for most workloads.

Has anyone found a non-synthetic benchmark where this makes a
significant difference?  Aside from btrfs, I mean.

-- 
Matthew Wilcox				Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."
--
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/