[Intel-gfx] [PATCH 2/2] igt/pm_rps: Add checks for freq = idle (RPn) in specific cases.
Bob Paauwe
bob.j.paauwe at intel.com
Thu Dec 3 16:43:58 PST 2015
On Tue, 1 Dec 2015 19:43:05 +0200
Imre Deak <imre.deak at intel.com> wrote:
> On ti, 2015-12-01 at 09:22 -0800, Bob Paauwe wrote:
> > On Tue, 1 Dec 2015 15:56:55 +0200
> > Imre Deak <imre.deak at intel.com> wrote:
> >
> > > On ma, 2015-11-30 at 16:23 -0800, Bob Paauwe wrote:
> > > > Now that the frequency can drop below the user specified minimum
> > > > when
> > > > the gpu is idle, add some checking to verify that it really does
> > > > drop
> > > > down to the RPn frequency in specific cases.
> > > >
> > > > To do this, modify the main test flow to take two 'check'
> > > > routines
> > > > instead of one. When running the config-min-max-idle subtest make
> > > > use of the second check routine to verify that the frequency
> > > > drops
> > > > to RPn instead of simply <= user min frequency. For all other
> > > > subtests, use the original check routines for both checks.
> > > >
> > > > Signed-off-by: Bob Paauwe <bob.j.paauwe at intel.com>
> > >
> > > I don't see the point. The frequency should always drop to the idle
> > > frequency if the GPU is idle, it's not enough that it's below MIN-
> > > freq.
> > > So why do we need separate CUR-freq<=MIN-freq and CUR-freq==idle-
> > > freq
> > > checks?
> >
> > I started from the premise that it should always drop to idle but
> > that's just not the case.
>
> It is the correct premise and if it doesn't hold then there is a real
> bug either in the testcase or the kernel which needs to be addressed
> differently. I haven't found anything concrete but one suspect is the
> logic that waits for the GPU idle condition, maybe the timeout
> value idle_check() or the hard-coded duration in do_load_gpu() is
> incorrect. In any case let's not paper over this issue, the very reason
> we have test cases is to uncover such bugs.
>
> > The min_max_config() function is used for
> > both the idle and loaded subtests. If you try to check for freq=idle
> > when doing the loaded subtest it will fail since it never goes idle.
> > Even in the idle subtest there are cases where it doesn't drop down
> > to
> > idle.
>
> The only place we should check for freq==idle is in idle_check() and
> that one is not called during the loaded subtest, it wouldn't even make
> sense to do so. So I'm not sure how this subtest fails for you.
>
> > I suppose I could duplicate min_max_config and have a
> > min_max_config_idle() and min_max_conifg_not_idle() for use by the
> > different subtests.
>
> The point of the "check" argument of min_max_config() is to distinguish
> between the idle and loaded cases. The check functions passed in know
> already if they can expect the frequency to reach the idle frequency
> or not.
>
> > The real problem is that the test was not designed to handle the case
> > where the freq could drop below min and probably needs to be
> > re-designed. I've been trying to find a quick fix vs. a complete
> > overhaul as this isn't really a priority for me.
>
> I think we only need your first patch and if there is any failure after
> that we have to root cause that and fix it properly.
>
> --Imre
You're right. I'm working with BXT and it seems like it's got some
unique issues with RPS. I just sent a new patch based on the first one
but with the changes you suggested to check for ==idle instead of <=min.
Maybe you have some insights into what I'm seeing with BXT? The first
problem I had was that I would see threshold up interrupts but not any
threshold down interrupts. The missing down interrupts was related to
the BIOS setting. I had runtime PM disabled so it seems strange that I
was getting the up interrupts.
With the BIOS setting corrected, the driver started disabling the down
interrupts once the freq dropped to min or just below because of the min
vs. idle difference. I have a patch for this that I'll send shortly.
The remaining issue seems to be some type of timing issue. I've had to
add a 35000us sleep between updating the interrupt enable register
(0xA168) and the posting read of freq. register (0xA008), otherwise it
acts like the change to the interrupt enable register never happened.
None of the documentation I have indicates that this is needed.
Bob
>
> >
> > >
> > > > ---
> > > > tests/pm_rps.c | 47 ++++++++++++++++++++++++++++++++++--------
> > > > -----
> > > > 1 file changed, 34 insertions(+), 13 deletions(-)
> > > >
> > > > diff --git a/tests/pm_rps.c b/tests/pm_rps.c
> > > > index f919625..96225ce 100644
> > > > --- a/tests/pm_rps.c
> > > > +++ b/tests/pm_rps.c
> > > > @@ -364,7 +364,7 @@ static int get_hw_rounded_freq(int target)
> > > > return ret;
> > > > }
> > > >
> > > > -static void min_max_config(void (*check)(void), bool load_gpu)
> > > > +static void min_max_config(void (*check)(void), void
> > > > (*check2)(void), bool load_gpu)
> > > > {
> > > > int fmid = (origfreqs[RPn] + origfreqs[RP0]) / 2;
> > > >
> > > > @@ -384,7 +384,7 @@ static void min_max_config(void
> > > > (*check)(void),
> > > > bool load_gpu)
> > > > writeval(stuff[MAX].filp, origfreqs[RP0]);
> > > > if (load_gpu)
> > > > do_load_gpu();
> > > > - check();
> > > > + check2();
> > > >
> > > > igt_debug("\nIncrease min to midpoint...\n");
> > > > writeval(stuff[MIN].filp, fmid);
> > > > @@ -412,7 +412,7 @@ static void min_max_config(void
> > > > (*check)(void),
> > > > bool load_gpu)
> > > > writeval(stuff[MIN].filp, origfreqs[RPn]);
> > > > if (load_gpu)
> > > > do_load_gpu();
> > > > - check();
> > > > + check2();
> > > >
> > > > igt_debug("\nDecrease min below RPn (invalid)...\n");
> > > > writeval_inval(stuff[MIN].filp, 0);
> > > > @@ -420,11 +420,11 @@ static void min_max_config(void
> > > > (*check)(void),
> > > > bool load_gpu)
> > > >
> > > > igt_debug("\nDecrease max to midpoint...\n");
> > > > writeval(stuff[MAX].filp, fmid);
> > > > - check();
> > > > + check2();
> > > >
> > > > igt_debug("\nDecrease max to RPn...\n");
> > > > writeval(stuff[MAX].filp, origfreqs[RPn]);
> > > > - check();
> > > > + check2();
> > > >
> > > > igt_debug("\nDecrease max below RPn (invalid)...\n");
> > > > writeval_inval(stuff[MAX].filp, 0);
> > > > @@ -436,11 +436,11 @@ static void min_max_config(void
> > > > (*check)(void),
> > > > bool load_gpu)
> > > >
> > > > igt_debug("\nIncrease max to midpoint...\n");
> > > > writeval(stuff[MAX].filp, fmid);
> > > > - check();
> > > > + check2();
> > > >
> > > > igt_debug("\nIncrease max to RP0...\n");
> > > > writeval(stuff[MAX].filp, origfreqs[RP0]);
> > > > - check();
> > > > + check2();
> > > >
> > > > igt_debug("\nIncrease max above RP0 (invalid)...\n");
> > > > writeval_inval(stuff[MAX].filp, origfreqs[RP0] + 1000);
> > > > @@ -461,7 +461,7 @@ static void basic_check(void)
> > > >
> > > > #define IDLE_WAIT_TIMESTEP_MSEC 100
> > > > #define IDLE_WAIT_TIMEOUT_MSEC 10000
> > > > -static void idle_check(void)
> > > > +static void idle_check_min(void)
> > > > {
> > > > int freqs[NUMFREQ];
> > > > int wait = 0;
> > > > @@ -482,6 +482,27 @@ static void idle_check(void)
> > > > igt_debug("Required %d msec to reach cur<=min\n", wait);
> > > > }
> > > >
> > > > +static void idle_check_idle(void)
> > > > +{
> > > > + int freqs[NUMFREQ];
> > > > + int wait = 0;
> > > > +
> > > > + /* Monitor frequencies until cur settles down to min,
> > > > which
> > > > should
> > > > + * happen within the allotted time */
> > > > + do {
> > > > + read_freqs(freqs);
> > > > + dump(freqs);
> > > > + checkit(freqs);
> > > > + if (freqs[CUR] == freqs[RPn])
> > > > + break;
> > > > + usleep(1000 * IDLE_WAIT_TIMESTEP_MSEC);
> > > > + wait += IDLE_WAIT_TIMESTEP_MSEC;
> > > > + } while (wait < IDLE_WAIT_TIMEOUT_MSEC);
> > > > +
> > > > + igt_assert_eq(freqs[CUR], freqs[RPn]);
> > > > + igt_debug("Required %d msec to reach cur=idle\n", wait);
> > > > +}
> > > > +
> > > > #define LOADED_WAIT_TIMESTEP_MSEC 100
> > > > #define LOADED_WAIT_TIMEOUT_MSEC 3000
> > > > static void loaded_check(void)
> > > > @@ -577,7 +598,7 @@ static void reset(void)
> > > >
> > > > igt_debug("Removing load...\n");
> > > > load_helper_stop();
> > > > - idle_check();
> > > > + idle_check_min();
> > > > }
> > > >
> > > > /*
> > > > @@ -635,7 +656,7 @@ static void blocking(void)
> > > > matchit(pre_freqs, post_freqs);
> > > >
> > > > igt_debug("Removing load...\n");
> > > > - idle_check();
> > > > + idle_check_min();
> > > > }
> > > >
> > > > static void pm_rps_exit_handler(int sig)
> > > > @@ -686,14 +707,14 @@ igt_main
> > > > }
> > > >
> > > > igt_subtest("basic-api")
> > > > - min_max_config(basic_check, false);
> > > > + min_max_config(basic_check, basic_check, false);
> > > >
> > > > igt_subtest("min-max-config-idle")
> > > > - min_max_config(idle_check, true);
> > > > + min_max_config(idle_check_min, idle_check_idle,
> > > > true);
> > > >
> > > > igt_subtest("min-max-config-loaded") {
> > > > load_helper_run(HIGH);
> > > > - min_max_config(loaded_check, false);
> > > > + min_max_config(loaded_check, loaded_check,
> > > > false);
> > > > load_helper_stop();
> > > > }
> > > >
> >
> >
> >
--
--
Bob Paauwe
Bob.J.Paauwe at intel.com
IOTG / PED Software Organization
Intel Corp. Folsom, CA
(916) 356-6193
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