linux-kernel - [PATCHv3 0/1] PM : cpuidle

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 linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Date:	Sat,  5 Sep 2009 01:04:12 +0530
From:	Sanjeev Premi <premi@...com>
To:	linux-kernel@...r.kernel.org
Cc:	Sanjeev Premi <premi@...com>
Subject: [PATCHv3 0/1] PM : cpuidle - incorrect statistics

When 'enable_off_mode' is 0, the target power state for MPU
and Core is locally changed to PWRDM_POWER_RET but, the
statistics are updated for idle state originally selected
by the governor.

To debug the issue and validate the fix, added variables -
mpu_state_modified and core_state_modified. Both are
incremented in omap3_enter_idle() as below:

	if (!enable_off_mode) {
		if (mpu_state < PWRDM_POWER_RET) {
			mpu_state_modified++;
			mpu_state = PWRDM_POWER_RET;
		}
		if (core_state < PWRDM_POWER_RET) {
			core_state_modified++;
			core_state = PWRDM_POWER_RET;
		}
	}

Also added a sysfs entry to track these modifications.

Before the change:

...BOOT...
[root@...P3EVM /]#
[root@...P3EVM /]# cat /sys/power/enable_off_mode
0
[root@...P3EVM /]# cat /sys/power/enable_off_mode
0
[root@...P3EVM /]# cat /sys/power/track_modifs
[mpu_state_modified, core_state_modified] = [0 , 0]
[root@...P3EVM /]#
[root@...P3EVM /]#
[root@...P3EVM /]# echo 1 > /sys/power/sleep_while_idle
[root@...P3EVM /]#
...WAIT 5 SECS...
[root@...P3EVM /]# cat /sys/power/track_modifs
[mpu_state_modified, core_state_modified] = [5 , 3]
[root@...P3EVM /]# cat /sys/devices/system/cpu/cpu0/cpuidle/state6/usage
3
...WAIT FEW MORE SECS...
[root@...P3EVM /]# cat /sys/power/track_modifs
[mpu_state_modified, core_state_modified] = [27 , 25]
[root@...P3EVM /]# cat /sys/devices/system/cpu/cpu0/cpuidle/state6/usage
25
[root@...P3EVM /]# cat /sys/power/enable_off_mode
0

After the fix:

...BOOT...
[root@...P3EVM /]#
[root@...P3EVM /]# cat /sys/power/enable_off_mode
0
[root@...P3EVM /]# cat /sys/power/enable_off_mode
0
[root@...P3EVM /]# cat /sys/power/track_modifs
[mpu_state_modified, core_state_modified] = [0 , 0]
[root@...P3EVM /]#
[root@...P3EVM /]#
[root@...P3EVM /]# echo 1 > /sys/power/sleep_while_idle
[root@...P3EVM /]#
...WAIT 5 SECS...
[root@...P3EVM /]# cat /sys/power/track_modifs
[mpu_state_modified, core_state_modified] = [0 , 0]
[root@...P3EVM /]# cat /sys/devices/system/cpu/cpu0/cpuidle/state6/usage
0
[root@...P3EVM /]# echo 1 > /sys/power/sleep_while_idle
[root@...P3EVM /]#
...WAIT APPROX 10 SECS...
[root@...P3EVM /]# cat /sys/power/track_modifs
[mpu_state_modified, core_state_modified] = [0 , 0]
[root@...P3EVM /]# cat /sys/devices/system/cpu/cpu0/cpuidle/state6/usage
2
...WAIT APPROX 30 SECS...
[root@...P3EVM /]# cat /sys/power/track_modifs
[mpu_state_modified, core_state_modified] = [0 , 0]
[root@...P3EVM /]# cat /sys/devices/system/cpu/cpu0/cpuidle/state6/usage
17
[root@...P3EVM /]#

This topic was discussed earlier; but the final fix did not find its
way back.

  [1] http://marc.info/?l=linux-omap&m=123681603821299&w=2

Sanjeev Premi (1):
  PM : cpuidle - update statistics for correct state

 arch/arm/mach-omap2/cpuidle34xx.c |   34 +++++++++++++++++++++++++++-------
 arch/arm/mach-omap2/pm.h          |    2 ++
 arch/arm/mach-omap2/pm34xx.c      |    2 ++
 3 files changed, 31 insertions(+), 7 deletions(-)

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