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

From: Vincent Guittot <vincent.guittot@linaro.org>
To: Guenter Roeck <linux@roeck-us.net>
Cc: ulf.hansson@linaro.org, dri-devel@lists.freedesktop.org,
	linux-pm@vger.kernel.org, airlied@linux.ie,
	intel-gfx@lists.freedesktop.org, rjw@rjwysocki.net,
	linux-kernel@vger.kernel.org, thara.gopinath@linaro.org,
	rodrigo.vivi@intel.com
Subject: Re: [PATCH v5 3/3] PM/runtime:Replace jiffies based accounting with ktime based accounting
Date: Fri, 18 Jan 2019 11:42:15 +0100	[thread overview]
Message-ID: <20190118104215.GA13168@linaro.org> (raw)
In-Reply-To: <20190117221628.GA21979@roeck-us.net>

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.

---
 drivers/base/power/runtime.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index ae1c728..118c7f6 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -66,7 +66,7 @@ static int rpm_suspend(struct device *dev, int rpmflags);
  */
 void update_pm_runtime_accounting(struct device *dev)
 {
-	u64 now = ktime_to_ns(ktime_get());
+	u64 now = ktime_get_mono_fast_ns();
 	u64 delta;
 
 	delta = now - dev->power.accounting_timestamp;
@@ -1507,7 +1507,7 @@ void pm_runtime_init(struct device *dev)
 	dev->power.request_pending = false;
 	dev->power.request = RPM_REQ_NONE;
 	dev->power.deferred_resume = false;
-	dev->power.accounting_timestamp = ktime_to_ns(ktime_get());
+	dev->power.accounting_timestamp = ktime_get_mono_fast_ns();
 	INIT_WORK(&dev->power.work, pm_runtime_work);
 
 	dev->power.timer_expires = 0;
-- 
2.7.4


> 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
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
