Re: SMP Pentium4 -- PAUSE Instruction

From: Dave Jones (davej@codemonkey.org.uk)
Date: Tue Dec 03 2002 - 10:55:29 EST

Next message: Stuart MacDonald: "Re: Race condition in tty_flip_buffer_push/flush_to_ldisc?"
Previous message: Nakajima, Jun: "RE: SMP Pentium4 -- PAUSE Instruction"
In reply to: Calin A. Culianu: "SMP Pentium4 -- PAUSE Instruction"
Next in thread: Arjan van de Ven: "Re: SMP Pentium4 -- PAUSE Instruction"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

On Tue, Dec 03, 2002 at 10:42:13AM -0500, Calin A. Culianu wrote:
>
> I as wondering -- according to Intel's docs they recommend that on a P4
> processor to use the PAUSE instruction (aka rep followed by a nop) inside
> any spin loop (such as one used in SMP spinlock code) in order to both
> improve processor performance and reduce power consumption.
> Is this instruction being used in spin-wait loops? For some reason, I am
> having a hard time figuring out whether or not it is being used. There is
> a rep_nop() in processor.h.. but I can't determine if that is being called
> for spin lock lock/unlock code.

there's also rep;nop in asm-i386/spinlock.h
See spin_lock_string()

Dave

-- 
| Dave Jones.        http://www.codemonkey.org.uk
| SuSE Labs
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Next message: Stuart MacDonald: "Re: Race condition in tty_flip_buffer_push/flush_to_ldisc?"
Previous message: Nakajima, Jun: "RE: SMP Pentium4 -- PAUSE Instruction"
In reply to: Calin A. Culianu: "SMP Pentium4 -- PAUSE Instruction"
Next in thread: Arjan van de Ven: "Re: SMP Pentium4 -- PAUSE Instruction"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

This archive was generated by hypermail 2b29 : Sat Dec 07 2002 - 22:00:16 EST