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  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, 18 Aug 2007 16:19:24 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Satyam Sharma <satyam@...radead.org>,
	Christoph Lameter <clameter@....com>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	Nick Piggin <nickpiggin@...oo.com.au>,
	Paul Mackerras <paulus@...ba.org>,
	Segher Boessenkool <segher@...nel.crashing.org>,
	heiko.carstens@...ibm.com, horms@...ge.net.au,
	linux-kernel@...r.kernel.org, rpjday@...dspring.com, ak@...e.de,
	netdev@...r.kernel.org, cfriesen@...tel.com,
	akpm@...ux-foundation.org, jesper.juhl@...il.com,
	linux-arch@...r.kernel.org, zlynx@....org, schwidefsky@...ibm.com,
	Chris Snook <csnook@...hat.com>, davem@...emloft.net,
	wensong@...ux-vs.org, wjiang@...ilience.com
Subject: Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures

On Sat, Aug 18, 2007 at 03:41:13PM -0700, Linus Torvalds wrote:
> 
> 
> On Sat, 18 Aug 2007, Paul E. McKenney wrote:
> > 
> > One of the gcc guys claimed that he thought that the two-instruction
> > sequence would be faster on some x86 machines.  I pointed out that
> > there might be a concern about code size.  I chose not to point out
> > that people might also care about the other x86 machines.  ;-)
> 
> Some (very few) x86 uarchs do tend to prefer "load-store" like code 
> generation, and doing a "mov [mem],reg + op reg" instead of "op [mem]" can 
> actually be faster on some of them. Not any that are relevant today, 
> though.

;-)

> Also, that has nothing to do with volatile, and should be controlled by 
> optimization flags (like -mtune). In fact, I thought there was a separate 
> flag to do that (ie something like "-mload-store"), but I can't find it, 
> so maybe that's just my fevered brain..

Good point, will suggest this if the need arises.

							Thanx, Paul
-
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Powered by blists - more mailing lists