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Message-ID: <20061004234141.749b13fb@localhost.localdomain>
Date: Wed, 4 Oct 2006 23:41:41 -0500
From: Olof Johansson <olof@...om.net>
To: paulus@...ba.org
Cc: linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org
Subject: [PATCH] powerpc: Enable DEEPNAP power savings mode on 970MP
Hi,
Without this patch, on an idle system I get:
cpu-power-0:21.638
cpu-power-1:27.102
cpu-power-2:29.343
cpu-power-3:25.784
Total: 103.8W
With this patch:
cpu-power-0:11.730
cpu-power-1:17.185
cpu-power-2:18.547
cpu-power-3:17.528
Total: 65.0W
If I lower HZ to 100, I can get it as low as:
cpu-power-0:10.938
cpu-power-1:16.021
cpu-power-2:17.245
cpu-power-3:16.145
Total: 60.2W
Another (older) Quad G5 went from 54W to 39W at HZ=250.
Coming back out of Deep Nap takes 40-70 cycles longer than coming back
from just Nap (which already takes quite a while). I don't think it'll
be a performance issue (interrupt latency on an idle system), but in
case someone does measurements feel free to report them.
Signed-off-by: Olof Johansson <olof@...om.net>
Index: linux-2.6/arch/powerpc/kernel/cpu_setup_ppc970.S
===================================================================
--- linux-2.6.orig/arch/powerpc/kernel/cpu_setup_ppc970.S
+++ linux-2.6/arch/powerpc/kernel/cpu_setup_ppc970.S
@@ -83,6 +83,22 @@ _GLOBAL(__setup_cpu_ppc970)
rldimi r0,r11,52,8 /* set NAP and DPM */
li r11,0
rldimi r0,r11,32,31 /* clear EN_ATTN */
+ b load_hids /* Jump to shared code */
+
+
+_GLOBAL(__setup_cpu_ppc970MP)
+ /* Do nothing if not running in HV mode */
+ mfmsr r0
+ rldicl. r0,r0,4,63
+ beqlr
+
+ mfspr r0,SPRN_HID0
+ li r11,0x15 /* clear DOZE and SLEEP */
+ rldimi r0,r11,52,6 /* set DEEPNAP, NAP and DPM */
+ li r11,0
+ rldimi r0,r11,32,31 /* clear EN_ATTN */
+
+load_hids:
mtspr SPRN_HID0,r0
mfspr r0,SPRN_HID0
mfspr r0,SPRN_HID0
Index: linux-2.6/arch/powerpc/kernel/cputable.c
===================================================================
--- linux-2.6.orig/arch/powerpc/kernel/cputable.c
+++ linux-2.6/arch/powerpc/kernel/cputable.c
@@ -41,6 +41,7 @@ extern void __setup_cpu_745x(unsigned lo
#endif /* CONFIG_PPC32 */
#ifdef CONFIG_PPC64
extern void __setup_cpu_ppc970(unsigned long offset, struct cpu_spec* spec);
+extern void __setup_cpu_ppc970MP(unsigned long offset, struct cpu_spec* spec);
extern void __restore_cpu_ppc970(void);
#endif /* CONFIG_PPC64 */
@@ -221,7 +222,7 @@ struct cpu_spec cpu_specs[] = {
.icache_bsize = 128,
.dcache_bsize = 128,
.num_pmcs = 8,
- .cpu_setup = __setup_cpu_ppc970,
+ .cpu_setup = __setup_cpu_ppc970MP,
.cpu_restore = __restore_cpu_ppc970,
.oprofile_cpu_type = "ppc64/970",
.oprofile_type = PPC_OPROFILE_POWER4,
-
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