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  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:	Mon, 3 Feb 2014 12:38:57 +0100
From:	Peter Zijlstra <>
To:	Ingo Molnar <>
Cc:	Waiman Long <>,
	Thomas Gleixner <>,
	Ingo Molnar <>,
	"H. Peter Anvin" <>, Arnd Bergmann <>,,,, Steven Rostedt <>,
	Andrew Morton <>,
	Michel Lespinasse <>,
	Andi Kleen <>,
	Rik van Riel <>,
	"Paul E. McKenney" <>,
	Linus Torvalds <>,
	Raghavendra K T <>,
	George Spelvin <>,
	Tim Chen <>,,
	Scott J Norton <>
Subject: Re: [PATCH v11 0/4] Introducing a queue read/write lock

On Sun, Feb 02, 2014 at 10:03:57AM +0100, Ingo Molnar wrote:
> * Waiman Long <> wrote:
> > How about making the selection of MCS or ticket queuing either user 
> > configurable or depending on the setting of NR_CPUS, NUMA, etc?
> No!
> There are lots of disadvantages to adding such CONFIG_NUMA Kconfig 
> variants for locking primitives:
>  - an doubling of the test matrix
>  - an doubling of the review matrix and a halving of effective review 
>    capacity: we've just about go the capacity to review and validate 
>    patches like this. Splitting out a 'only NUMA cares' variant is a 
>    non-starter really.
>  - but most importantly, there's absolutely no reason to not be fast
>    on 128 CPU systems in the low contended case either! Sacrificing
>    the low contended case with 'on 128 CPU systems it is the contended
>    path that matters' is an idiotic argument.

Not to mention distros will only ever pick one.

Also, there's probably several orders of magnitude more single and dual
socket systems out there than there are quad or bigger systems.

So even if the lightly contended case is say only 1% slower, that could
still add up to more cycles lost than won over all computers out there
running Linux.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists