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powerpc: Don't spin on sync instruction at boot time

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Push the sync below the secondary smp init hold loop and comment its purpose.
This should speed up boot by reducing global traffic during the single-threaded
portion of boot.

Signed-off-by: Sonny Rao <sonnyrao@us.ibm.com>
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Sonny Rao 2008-07-12 09:00:26 +10:00 committed by Benjamin Herrenschmidt
parent cd6f37be7f
commit b6f6b98a4e
1 changed files with 2 additions and 1 deletions
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3
arch/powerpc/kernel/head_64.S
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@ -1198,7 +1198,6 @@ _GLOBAL(generic_secondary_smp_init)
3: HMT_LOW
lbz r23,PACAPROCSTART(r13) /* Test if this processor should */
/* start. */
sync
#ifndef CONFIG_SMP
b 3b /* Never go on non-SMP */
@ -1206,6 +1205,8 @@ _GLOBAL(generic_secondary_smp_init)
cmpwi 0,r23,0
beq 3b /* Loop until told to go */
sync /* order paca.run and cur_cpu_spec */
/* See if we need to call a cpu state restore handler */
LOAD_REG_IMMEDIATE(r23, cur_cpu_spec)
ld r23,0(r23)