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Commit 5b43d20a authored by Olof Johansson's avatar Olof Johansson Committed by Paul Mackerras
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[POWERPC] powerpc: Enable DEEPNAP power savings mode on 970MP 



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: default avatarOlof Johansson <olof@lixom.net>
Acked-by: default avatarMichael Buesch <mb@bu3sch.de>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent d04c56f7

arch/powerpc/kernel/cpu_setup_ppc970.S

+16 −0
Original line number Diff line number Diff line
@@ -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

arch/powerpc/kernel/cputable.c

+2 −1
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ extern void __setup_cpu_745x(unsigned long offset, struct cpu_spec* spec); 
#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,