Messages in this thread | | | Subject | Re: [PATCH v5 3/3] PM/runtime:Replace jiffies based accounting with ktime based accounting | From | Guenter Roeck <> | Date | Fri, 18 Jan 2019 04:08:39 -0800 |
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On 1/18/19 3:05 AM, Rafael J. Wysocki wrote: > On Fri, Jan 18, 2019 at 11:53 AM Vincent Guittot > <vincent.guittot@linaro.org> wrote: >> >> On Fri, 18 Jan 2019 at 11:42, Vincent Guittot >> <vincent.guittot@linaro.org> wrote: >>> >>> Hi Guenter, >>> >>> Le Thursday 17 Jan 2019 à 14:16:28 (-0800), Guenter Roeck a écrit : >>>> On Fri, Dec 21, 2018 at 11:33:56AM +0100, Vincent Guittot wrote: >>>>> From: Thara Gopinath <thara.gopinath@linaro.org> >>>>> >>>>> This patch replaces jiffies based accounting for runtime_active_time >>>>> and runtime_suspended_time with ktime base accounting. This makes the >>>>> runtime debug counters inline with genpd and other pm subsytems which >>>>> uses ktime based accounting. >>>>> >>>>> timekeeping is initialized before pm_runtime_init() so ktime_get() will >>>>> be ready before first call. In fact, timekeeping_init() is called early >>>>> in start_kernel() which is way before driver_init() (and that's when >>>>> devices can start to be initialized) called from rest_init() via >>>>> kernel_init_freeable() and do_basic_setup(). >>>>> >>>> This is not (always) correct. My qemu "collie" boot test fails with this >>>> patch applied. Reverting the patch fixes the problem. Bisect log attached. >>>> >>> >>> Can you try the patch below ? >>> ktime_get_mono_fast_ns() has the advantage of being init with dummy clock so >>> it can be used at early_init. >> >> Another possibility would be delay the init of the gpiochip > > Well, right. > > Initializing devices before timekeeping doesn't feel particularly > robust from the design perspective. > > How exactly does that happen? >
With an added 'initialized' flag and backtrace into the timekeeping code, with the change suggested earlier applied:
------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at kernel/time/timekeeping.c:453 ktime_get_mono_fast_ns+0x114/0x12c Timekeeping not initialized CPU: 0 PID: 0 Comm: swapper Not tainted 5.0.0-rc2-next-20190117-dirty #2 Hardware name: Sharp-Collie Backtrace: [<c000dce8>] (dump_backtrace) from [<c000df78>] (show_stack+0x18/0x1c) r7:00000009 r6:00000000 r5:c065ba90 r4:c06d3e54 [<c000df60>] (show_stack) from [<c0588930>] (dump_stack+0x20/0x28) [<c0588910>] (dump_stack) from [<c0018ae8>] (__warn+0xcc/0xf4) [<c0018a1c>] (__warn) from [<c0018b5c>] (warn_slowpath_fmt+0x4c/0x6c) r8:df407b08 r7:00000000 r6:c0c01550 r5:c065bad8 r4:c06dd028 [<c0018b14>] (warn_slowpath_fmt) from [<c0069e2c>] (ktime_get_mono_fast_ns+0x114/0x12c) r3:00000000 r2:c065bad8 r5:00000000 r4:df407b08 [<c0069d18>] (ktime_get_mono_fast_ns) from [<c03c7810>] (pm_runtime_init+0x38/0xb8) r9:c06c9a5c r8:df407b08 r7:00000000 r6:c0c01550 r5:00000000 r4:df407b08 [<c03c77d8>] (pm_runtime_init) from [<c03b6a34>] (device_initialize+0xb0/0xec) r7:00000000 r6:c0c01550 r5:00000000 r4:df407b08 [<c03b6984>] (device_initialize) from [<c0366d30>] (gpiochip_add_data_with_key+0x9c/0x884) r7:00000000 r6:c06fca34 r5:00000000 r4:00000000 [<c0366c94>] (gpiochip_add_data_with_key) from [<c06b9708>] (sa1100_init_gpio+0x40/0x98) r10:dfffcd60 r9:c06c9a5c r8:c06dd020 r7:c06dd028 r6:ffffffff r5:00000000 r4:c06fca34 [<c06b96c8>] (sa1100_init_gpio) from [<c06ae58c>] (sa1100_init_irq+0x2c/0x3c) r7:c06dd028 r6:ffffffff r5:c0713300 r4:c06e1070 [<c06ae560>] (sa1100_init_irq) from [<c06aab1c>] (init_IRQ+0x20/0x28) r5:c0713300 r4:00000000 [<c06aaafc>] (init_IRQ) from [<c06a7cd0>] (start_kernel+0x254/0x4cc) [<c06a7a7c>] (start_kernel) from [<00000000>] ( (null)) r10:0000717f r9:6901b119 r8:c0000100 r7:00000092 r6:0000313d r5:00000053 r4:c06a7330 ---[ end trace 91e1bd00dd7cce32 ]---
Guenter
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