Bug 76877

*** This bug has been marked as a duplicate of bug 76542 ***

Daniel, I do not believe this is a duplicate. In this bug they enter RC6, but the residency counter ends up with a longer time than the system had slept.

Is this still an issue with latest kernel+igt?

(In reply to comment #3)
> Is this still an issue with latest kernel+igt?

Yeah, I use the same script to test on -nightly_f79ba7_20140519.

real    0m10.001s
user    0m0.000s
sys     0m0.002s
BEFORE = 2198119
AFTER = 2209562
DELTA = 11443
1.14

This bug is able to reproduce on HSW on latest -fixes(223a6f2b975ab35d93270ea1d4fb6e0ac6b27fe6)

BEFORE = 221873
AFTER = 226900
DELTA = 5027
1.00540

I'm not seeing this here on my BYT or HSW.  Does it happen everytime for you when idle?  Is the screen on or off?

I'm not sure if these regs are guaranteed to be accurate; they may be saved & restored by the PUnit with some sort of compensating value added, so I'm not sure if this is a real bug or not.

There are a few things going on here:
  - the rc6 residency counters don't have a high precision (some of the data feeding into it is only updated at 1ms intervals)
  - reading from userspace introduces potential error, since the reads may occur further apart than the "time" and "sleep" commands indicate due to scheduling etc.

So I'm closing this as WONTFIX.  We'll have to tolerate some imprecision in these counters.  Since they're for debug only, that should be fine.

*** Bug 85902 has been marked as a duplicate of this bug. ***

I've recently looked at this together with Tim Gore from vpg and the testcase checks for something that just doesn't work. This isn't just inaccuracy in counters but a broken testcase.

So reopening. One solution might be to revert the testcase to a state before the accuracy checks where added.

Checked with Jesse, he agreed that " the time and sleep commands won't give a script enough precision to evaluate the residency difference accurately."

So, pls revert the rc6_residency check patch, thanks.

I think Guo conflated the issue. The numbers reported can't be higher than the actual time slept, regardless of clock granularity. Okay, if you round up sometimes, it can be off by a little, but the amount we're off is actually huge. 

In other words, what Guo reported in #5 is likely just that, approximation error which can easily by fixed with a tiny bit of math to give some amount of fudge in the positive direction. However, the original numbers that Wendy reported aren't multiple reads, there are exactly 2 reads, and the application completed in exactly 0m10.002s. I don't believe this explanation for the 1.14


real 0m10.002s
user 0m0.000s
sys 0m0.002s
BEFORE = 1281484
AFTER = 1292928
DELTA = 11444
1.14

*** Bug 85391 has been marked as a duplicate of this bug. ***

*** Bug 85392 has been marked as a duplicate of this bug. ***

Does this still happen now that Deepak's patch to add some fuzz has been applied?  If that's not enough we may need to increase the fuzz a bit more, since there's not much we can do about incorrect residency counters (which are really just a debug feature anyway).

(In reply to Jesse Barnes from comment #14)
> Does this still happen now that Deepak's patch to add some fuzz has been
> applied?  If that's not enough we may need to increase the fuzz a bit more,
> since there's not much we can do about incorrect residency counters (which
> are really just a debug feature anyway).

Jesse, would you give the link of Deepak's patch, then we can check it? Thanks.

Update BYT platform measured RC6 residency counter number, which was based on latest igt version.

root@x-byt06:/GFX/Test/Intel_gpu_tools/intel-gpu-tools/tests# ./pm_rc6_residency
IGT-Version: 1.10-ga172676 (x86_64) (Linux: 4.0.0-rc4_drm-intel-nightly_3753ea_20150318+ x86_64)
The residency counter: 1.125574
Test assertion failure function residency_accuracy, file pm_rc6_residency.c:130:
Failed assertion: (flag_counter != 0) && (counter_result <=1)
Sysfs RC6 residency counter is inaccurate.
Subtest rc6-accuracy failed.
**** DEBUG ****
The residency counter: 1.125574
Test requirement passed: !(flag_support == 0)
Test assertion failure function residency_accuracy, file pm_rc6_residency.c:130:
Failed assertion: (flag_counter != 0) && (counter_result <=1)
Sysfs RC6 residency counter is inaccurate.
****  END  ****
Subtest rc6-accuracy: FAIL (0.000s)
Test assertion failure function residency_accuracy, file pm_rc6_residency.c:101:
Failed assertion: diff <= (SLEEP_DURATION + RC6_FUDGE)
Diff was too high. That is unpossible
Subtest media-rc6-accuracy failed.
**** DEBUG ****
Test assertion failure function residency_accuracy, file pm_rc6_residency.c:101:
Failed assertion: diff <= (SLEEP_DURATION + RC6_FUDGE)
Diff was too high. That is unpossible
****  END  ****
Subtest media-rc6-accuracy: FAIL (0.000s)
This platform doesn't support RC6p
Subtest rc6p-accuracy: SKIP (0.001s)
This platform doesn't support RC6pp
Subtest rc6pp-accuracy: SKIP (0.000s)

It still fails on BYT, but it works well on other platforms.
output on BYT:
IGT-Version: 1.10-g308b0e8 (x86_64) (Linux: 4.1.0-rc3_drm-intel-nightly_056608_20150519+ x86_64)
Residency in rc6 or deeper state: 3340 ms (ratio to expected duration: 1.10)
Test assertion failure function residency_accuracy, file pm_rc6_residency.c:109:
Failed assertion: ratio > 0.9 && ratio <= 1
Sysfs RC6 residency counter is inaccurate.
Stack trace:
  #0 [__igt_fail_assert+0xf1]
  #1 [readit+0x0]
  #2 [__real_main178+0x10d]
  #3 [main+0x29]
  #4 [__libc_start_main+0xf5]
  #5 [_start+0x29]
  #6 [<unknown>+0x29]
Subtest rc6-accuracy failed.
**** DEBUG ****
Test requirement passed: !(!(rc6_mask & RC6_ENABLED))
Residency in rc6 or deeper state: 3340 ms (ratio to expected duration: 1.10)
Test assertion failure function residency_accuracy, file pm_rc6_residency.c:109:
Failed assertion: ratio > 0.9 && ratio <= 1
Sysfs RC6 residency counter is inaccurate.
****  END  ****
Subtest rc6-accuracy: FAIL (0.002s)
Residency in media_rc6 or deeper state: 3341 ms (ratio to expected duration: 1.10)
Test assertion failure function residency_accuracy, file pm_rc6_residency.c:109:
Failed assertion: ratio > 0.9 && ratio <= 1
Last errno: 22, Invalid argument
Sysfs RC6 residency counter is inaccurate.
Stack trace:
  #0 [__igt_fail_assert+0xf1]
  #1 [readit+0x0]
  #2 [__real_main178+0x190]
  #3 [main+0x29]
  #4 [__libc_start_main+0xf5]
  #5 [_start+0x29]
  #6 [<unknown>+0x29]
Subtest media-rc6-accuracy failed.
**** DEBUG ****
Test requirement passed: !(!((rc6_mask & RC6_ENABLED) && (IS_VALLEYVIEW(devid) || IS_CHERRYVIEW(devid))))
Residency in media_rc6 or deeper state: 3341 ms (ratio to expected duration: 1.10)
Test assertion failure function residency_accuracy, file pm_rc6_residency.c:109:
Failed assertion: ratio > 0.9 && ratio <= 1
Last errno: 22, Invalid argument
Sysfs RC6 residency counter is inaccurate.
****  END  ****
Subtest media-rc6-accuracy: FAIL (0.003s)
Test requirement not met in function __real_main178, file pm_rc6_residency.c:209:
Test requirement: !(!(rc6_mask & RC6P_ENABLED))
Last errno: 22, Invalid argument
Subtest rc6p-accuracy: SKIP (0.000s)
Test requirement not met in function __real_main178, file pm_rc6_residency.c:214:
Test requirement: !(!(rc6_mask & RC6PP_ENABLED))
Last errno: 22, Invalid argument
Subtest rc6pp-accuracy: SKIP (0.000s)

Created attachment 116110 [details] [review]
Debug patch

Could you run the test again with the attached patched applied on igt? That should provide a bit of additional information.

This should be fixed by the following patch, could you give it a try?:

http://lists.freedesktop.org/archives/intel-gfx/2015-May/066871.html

(In reply to Imre Deak from comment #19)
> This should be fixed by the following patch, could you give it a try?:
> 
> http://lists.freedesktop.org/archives/intel-gfx/2015-May/066871.html

Yes, this patch can fix this issue on BYT, other platforms also pass.

root@x-byt01:/GFX/Test/Intel_gpu_tools/intel-gpu-tools/tests# ./pm_rc6_residency
IGT-Version: 1.10-gf497238 (x86_64) (Linux: 4.1.0-rc5_kcloud_b03656_20150529+ x86_64)
Residency in rc6 or deeper state: 3001 ms (ratio to expected duration: 0.98)
Subtest rc6-accuracy: SUCCESS (0.000s)
Residency in media_rc6 or deeper state: 3001 ms (ratio to expected duration: 0.98)
Subtest media-rc6-accuracy: SUCCESS (0.000s)
Test requirement not met in function __real_main178, file pm_rc6_residency.c:209:
Test requirement: !(!(rc6_mask & RC6P_ENABLED))
Subtest rc6p-accuracy: SKIP (0.000s)
Test requirement not met in function __real_main178, file pm_rc6_residency.c:214:
Test requirement: !(!(rc6_mask & RC6PP_ENABLED))
Subtest rc6pp-accuracy: SKIP (0.000s)

root@x-bdw05:/GFX/Test/Intel_gpu_tools/intel-gpu-tools/tests# ./pm_rc6_residency
IGT-Version: 1.10-gf497238 (x86_64) (Linux: 4.1.0-rc5_kcloud_b03656_20150529+ x86_64)
Residency in rc6 or deeper state: 3009 ms (ratio to expected duration: 0.99)
Subtest rc6-accuracy: SUCCESS (0.000s)
Test requirement not met in function __real_main178, file pm_rc6_residency.c:204:
Test requirement: !(!((rc6_mask & RC6_ENABLED) && (IS_VALLEYVIEW(devid) || IS_CHERRYVIEW(devid))))
Subtest media-rc6-accuracy: SKIP (0.000s)
Test requirement not met in function __real_main178, file pm_rc6_residency.c:209:
Test requirement: !(!(rc6_mask & RC6P_ENABLED))
Subtest rc6p-accuracy: SKIP (0.000s)
Test requirement not met in function __real_main178, file pm_rc6_residency.c:214:
Test requirement: !(!(rc6_mask & RC6PP_ENABLED))
Subtest rc6pp-accuracy: SKIP (0.000s)

[root@x-ivb9 tests]# ./pm_rc6_residency
IGT-Version: 1.10-g308b0e8 (x86_64) (Linux: 4.1.0-rc5_kcloud_b03656_20150529+ x86_64)
Residency in rc6 or deeper state: 2975 ms (ratio to expected duration: 0.98)
Subtest rc6-accuracy: SUCCESS (0.000s)
Test requirement not met in function __real_main178, file pm_rc6_residency.c:204:
Test requirement: !(!((rc6_mask & RC6_ENABLED) && (IS_VALLEYVIEW(devid) || IS_CHERRYVIEW      (devid))))
Subtest media-rc6-accuracy: SKIP (0.000s)
Residency in rc6p or deeper state: 2975 ms (ratio to expected duration: 0.98)
Subtest rc6p-accuracy: SUCCESS (0.000s)
Test requirement not met in function __real_main178, file pm_rc6_residency.c:214:
Test requirement: !(!(rc6_mask & RC6PP_ENABLED))
Subtest rc6pp-accuracy: SKIP (0.000s)

(In reply to wendy.wang from comment #20)
> (In reply to Imre Deak from comment #19)
> > This should be fixed by the following patch, could you give it a try?:
> > 
> > http://lists.freedesktop.org/archives/intel-gfx/2015-May/066871.html
> 
> Yes, this patch can fix this issue on BYT, other platforms also pass.

Thanks for testing it. Note that the status should be changed to 'RESOLVED/FIXED' only when the fix gets merged. The above fix is still lacking a reviewed-by, so I'll follow up on it on the mailing list. Meanwhile reopening this.

Fixed in -nightly by

commit 66c826a1754c07012e29fbe9be7013e92a5acbac
Author: Imre Deak <imre.deak@intel.com>
Date:   Mon Jun 1 10:32:01 2015 +0300

    drm/i915/vlv: fix RC6 residency time calculation

Verified latest drm-intel-nightly_8207b9_20150616+ kernel on BDW, this problem has been fixed, So closed.

output info:
------------------------
root@x-byt01:/GFX/Test/Intel_gpu_tools/intel-gpu-tools/tests# ./pm_rc6_residency
IGT-Version: 1.11-gc83299d (x86_64) (Linux: 4.1.0-rc8_drm-intel-nightly_8207b9_20150616+ x86_64)
Residency in rc6 or deeper state: 3000 ms (ratio to expected duration: 0.98)
Subtest rc6-accuracy: SUCCESS (0.000s)
Residency in media_rc6 or deeper state: 3001 ms (ratio to expected duration: 0.98)
Subtest media-rc6-accuracy: SUCCESS (0.000s)
Test requirement not met in function __real_main178, file pm_rc6_residency.c:209:
Test requirement: !(!(rc6_mask & RC6P_ENABLED))
Subtest rc6p-accuracy: SKIP (0.000s)
Test requirement not met in function __real_main178, file pm_rc6_residency.c:214:
Test requirement: !(!(rc6_mask & RC6PP_ENABLED))
Subtest rc6pp-accuracy: SKIP (0.000s)

Closing old verified.