linux-kernel - Re: [PATCH v5 3/3] PM/runtime:Replace jiffies based accounting with ktime based accounting

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Message-ID: <20190117221628.GA21979@roeck-us.net>
Date:   Thu, 17 Jan 2019 14:16:28 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        rjw@...ysocki.net, thara.gopinath@...aro.org,
        jani.nikula@...ux.intel.com, joonas.lahtinen@...ux.intel.com,
        rodrigo.vivi@...el.com, airlied@...ux.ie,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        ulf.hansson@...aro.org
Subject: Re: [PATCH v5 3/3] PM/runtime:Replace jiffies based accounting with
 ktime based accounting

On Fri, Dec 21, 2018 at 11:33:56AM +0100, Vincent Guittot wrote:
> From: Thara Gopinath <thara.gopinath@...aro.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.

With some added debugging:

...
IRQS: 16, nr_irqs: 65, preallocated irqs: 65
irq: Cannot allocate irq_descs @ IRQ1, assuming pre-allocated
gpio gpiochip0: ############### pm_runtime_init() ############
irq: Cannot allocate irq_descs @ IRQ33, assuming pre-allocated
############## timekeeping_init() ####################
sched_clock: 32 bits at 3686kHz, resolution 271ns, wraps every 582542222200ns^M
...

This is with:

void pm_runtime_init(struct device *dev)
{
+       dev_info(dev, "############### pm_runtime_init() ############\n");
+
...
@@ -1526,6 +1526,8 @@ void __init timekeeping_init(void)
	struct clocksource *clock;
	unsigned long flags;
		 
+       pr_info("############## timekeeping_init() ####################\n");
+

Guenter

---
# bad: [a37d50ca3b837c19a297f349365d11a20c1087d0] Add linux-next specific files for 20190117
# good: [1c7fc5cbc33980acd13d668f1c8f0313d6ae9fd8] Linux 5.0-rc2
git bisect start 'HEAD' 'v5.0-rc2'
# bad: [4edb817d29fdf19fb5d52784bb3c29c40e00f586] Merge remote-tracking branch 'pm/linux-next'
git bisect bad 4edb817d29fdf19fb5d52784bb3c29c40e00f586
# good: [6d95886720d306a1914a7c9a8aeb0bcbc7aef018] Merge remote-tracking branch 'omap/for-next'
git bisect good 6d95886720d306a1914a7c9a8aeb0bcbc7aef018
# good: [975b5cdd74430bc8a04f832d65a47cdb95b73fec] Merge remote-tracking branch 'fuse/for-next'
git bisect good 975b5cdd74430bc8a04f832d65a47cdb95b73fec
# good: [112386d2189fc54b979c3a8bf64b2908df91e123] Merge remote-tracking branch 'i2c/i2c/for-next'
git bisect good 112386d2189fc54b979c3a8bf64b2908df91e123
# good: [3943f059823b6e15884387f31618b84826e924b3] media: coda: Add control for h.264 chroma qp index offset
git bisect good 3943f059823b6e15884387f31618b84826e924b3
# good: [44970bbbbb5079ee100875b06e45db5d6e91a16e] Merge remote-tracking branch 'v4l-dvb/master'
git bisect good 44970bbbbb5079ee100875b06e45db5d6e91a16e
# bad: [599170c2b860aca3364574f833bb9cc801c9668d] Merge branch 'pm-core' into linux-next
git bisect bad 599170c2b860aca3364574f833bb9cc801c9668d
# good: [347d570919ca9a3a3653ce9cbb7399c7c0ba8248] Merge branch 'acpi-pci' into linux-next
git bisect good 347d570919ca9a3a3653ce9cbb7399c7c0ba8248
# good: [e0a9fde86ba1bc26dd754c733b32e70cd8f1c187] Merge branches 'acpi-tables' and 'acpi-apei' into linux-next
git bisect good e0a9fde86ba1bc26dd754c733b32e70cd8f1c187
# good: [3b4ed2e2eb5583774a1ed4aa4596a5a3c55f2567] drm/i915: Move on the new pm runtime interface
git bisect good 3b4ed2e2eb5583774a1ed4aa4596a5a3c55f2567
# bad: [c75c303933a68c547f3352d1d708843f9449d3f4] PM: clock_ops: fix missing clk_prepare() return value check
git bisect bad c75c303933a68c547f3352d1d708843f9449d3f4
# bad: [3982ab9ce433efc72ca31eb9ddc85d9355966444] PM-runtime: Replace jiffies based accounting with ktime-based accounting
git bisect bad 3982ab9ce433efc72ca31eb9ddc85d9355966444
# first bad commit: [3982ab9ce433efc72ca31eb9ddc85d9355966444] PM-runtime: Replace jiffies based accounting with ktime-based accounting