Re: [ANNOUNCE] 4.4-rc6-rt1

From: Tim Sander
Date: Thu Jan 07 2016 - 07:15:44 EST


Hi Sebastian

Thanks for your christmas present :-).

Am Mittwoch, 23. Dezember 2015, 23:57:55 schrieb Sebastian Andrzej Siewior:
> Please don't continue reading before christmas eve (or morning,
> depending on your schedule). If you don't celebrate christmas,
> well go ahead.
Ok, i have to admit i am a little late to the party.
> Dear RT folks!
>
> I'm pleased to announce the v4.4-rc6-rt1 patch set. I tested it on my
> AMD A10, 64bit. Nothing exploded so far, filesystem is still there.
> I haven't tested it on anything else. Before someone asks: this does not
> mean it does *not* work on ARM I simply did not try it.
With the trivial compile patch below it is working on ARM:
Specifically two Cortex A9 on a CycloneV from Altera.

The performance without load looks good:
# Total: 100000000 100000000
# Min Latencies: 00009 00009
# Avg Latencies: 00010 00010
# Max Latencies: 00022 00033

A short run with hackbench load reveals an latency "island" from 54-69µs on the first core.
There are no timer ticks with 34 to 53 µs delay.
# Total: 001000000 000999714
# Min Latencies: 00010 00009
# Avg Latencies: 00017 00010
# Max Latencies: 00069 00029

I will test further and report if i find strange occurences.

> If you are brave then download it, install it and have fun. If something
> breaks, please report it. If your machine starts blinking like a
> christmas tree while using the patch then *please* send a photo.
Sorry no photos, no special blinking.
Best regards
Tim

Signed-off-by: Tim Sander <tim@xxxxxxxxxxxxxxx>

--- linux-4.4-rc6/kernel/time/hrtimer.c.orig 2016-01-06 16:56:32.573527206 +0100
+++ linux-4.4-rc6/kernel/time/hrtimer.c 2016-01-06 16:56:48.213215320 +0100
@@ -1435,6 +1435,7 @@

#endif

+static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer);

static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now)
{
@@ -1490,8 +1491,6 @@
raise_softirq_irqoff(HRTIMER_SOFTIRQ);
}

-static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer);
-
#ifdef CONFIG_HIGH_RES_TIMERS

/*
--
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