The rt boosting in locktorture has a factor variable s currently large enough
that boosting only happens once every minute or so. Add a tunable to reduce the
factor so that boosting happens more often, to test paths and arrive at failure
modes earlier. With this change, I can set the factor to like 50 and have the
boosting happens every 10 seconds or so.
Tested with boot parameters:
locktorture.torture_type=mutex_lock
locktorture.onoff_interval=1
locktorture.nwriters_stress=8
locktorture.stutter=0
locktorture.rt_boost=1
locktorture.rt_boost_factor=50
locktorture.nlocks=3
Signed-off-by: Joel Fernandes (Google) <[email protected]>
---
kernel/locking/locktorture.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 8968fd65a90d..b64a528e511c 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -48,6 +48,7 @@ torture_param(int, stat_interval, 60,
torture_param(int, stutter, 5, "Number of jiffies to run/halt test, 0=disable");
torture_param(int, rt_boost, 2,
"Do periodic rt-boost. 0=Disable, 1=Only for rt_mutex, 2=For all lock types.");
+torture_param(int, rt_boost_factor, 50, "A factor determining how often rt-boost happens.");
torture_param(int, verbose, 1,
"Enable verbose debugging printk()s");
torture_param(int, nlocks, 1,
@@ -133,12 +134,12 @@ static void torture_lock_busted_write_unlock(int tid __maybe_unused)
static void __torture_rt_boost(struct torture_random_state *trsp)
{
- const unsigned int factor = 50000; /* yes, quite arbitrary */
+ const unsigned int factor = rt_boost_factor;
if (!rt_task(current)) {
/*
- * Boost priority once every ~50k operations. When the
- * task tries to take the lock, the rtmutex it will account
+ * Boost priority once every rt_boost_factor operations. When
+ * the task tries to take the lock, the rtmutex it will account
* for the new priority, and do any corresponding pi-dance.
*/
if (trsp && !(torture_random(trsp) %
@@ -148,8 +149,9 @@ static void __torture_rt_boost(struct torture_random_state *trsp)
return;
} else {
/*
- * The task will remain boosted for another ~500k operations,
- * then restored back to its original prio, and so forth.
+ * The task will remain boosted for another 10*rt_boost_factor
+ * operations, then restored back to its original prio, and so
+ * forth.
*
* When @trsp is nil, we want to force-reset the task for
* stopping the kthread.
--
2.39.0.rc1.256.g54fd8350bd-goog
On Fri, 09 Dec 2022, Joel Fernandes (Google) wrote:
>The rt boosting in locktorture has a factor variable s currently large enough
>that boosting only happens once every minute or so. Add a tunable to reduce the
>factor so that boosting happens more often, to test paths and arrive at failure
>modes earlier. With this change, I can set the factor to like 50 and have the
>boosting happens every 10 seconds or so.
>
>Tested with boot parameters:
>locktorture.torture_type=mutex_lock
>locktorture.onoff_interval=1
>locktorture.nwriters_stress=8
>locktorture.stutter=0
>locktorture.rt_boost=1
>locktorture.rt_boost_factor=50
>locktorture.nlocks=3
>
>Signed-off-by: Joel Fernandes (Google) <[email protected]>
Reviewed-by: Davidlohr Bueso <[email protected]>
>---
> kernel/locking/locktorture.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
>diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
>index 8968fd65a90d..b64a528e511c 100644
>--- a/kernel/locking/locktorture.c
>+++ b/kernel/locking/locktorture.c
>@@ -48,6 +48,7 @@ torture_param(int, stat_interval, 60,
> torture_param(int, stutter, 5, "Number of jiffies to run/halt test, 0=disable");
> torture_param(int, rt_boost, 2,
> "Do periodic rt-boost. 0=Disable, 1=Only for rt_mutex, 2=For all lock types.");
>+torture_param(int, rt_boost_factor, 50, "A factor determining how often rt-boost happens.");
> torture_param(int, verbose, 1,
> "Enable verbose debugging printk()s");
> torture_param(int, nlocks, 1,
>@@ -133,12 +134,12 @@ static void torture_lock_busted_write_unlock(int tid __maybe_unused)
>
> static void __torture_rt_boost(struct torture_random_state *trsp)
> {
>- const unsigned int factor = 50000; /* yes, quite arbitrary */
>+ const unsigned int factor = rt_boost_factor;
>
> if (!rt_task(current)) {
> /*
>- * Boost priority once every ~50k operations. When the
>- * task tries to take the lock, the rtmutex it will account
>+ * Boost priority once every rt_boost_factor operations. When
>+ * the task tries to take the lock, the rtmutex it will account
Nit: maybe refer to it as 'rt_boost_factor'?
> * for the new priority, and do any corresponding pi-dance.
> */
> if (trsp && !(torture_random(trsp) %
>@@ -148,8 +149,9 @@ static void __torture_rt_boost(struct torture_random_state *trsp)
> return;
> } else {
> /*
>- * The task will remain boosted for another ~500k operations,
>- * then restored back to its original prio, and so forth.
>+ * The task will remain boosted for another 10*rt_boost_factor
>+ * operations, then restored back to its original prio, and so
>+ * forth.
> *
> * When @trsp is nil, we want to force-reset the task for
> * stopping the kthread.
>--
>2.39.0.rc1.256.g54fd8350bd-goog
>
On Fri, Dec 9, 2022 at 5:02 PM Davidlohr Bueso <[email protected]> wrote:
>
> On Fri, 09 Dec 2022, Joel Fernandes (Google) wrote:
>
> >The rt boosting in locktorture has a factor variable s currently large enough
> >that boosting only happens once every minute or so. Add a tunable to reduce the
> >factor so that boosting happens more often, to test paths and arrive at failure
> >modes earlier. With this change, I can set the factor to like 50 and have the
> >boosting happens every 10 seconds or so.
> >
> >Tested with boot parameters:
> >locktorture.torture_type=mutex_lock
> >locktorture.onoff_interval=1
> >locktorture.nwriters_stress=8
> >locktorture.stutter=0
> >locktorture.rt_boost=1
> >locktorture.rt_boost_factor=50
> >locktorture.nlocks=3
> >
> >Signed-off-by: Joel Fernandes (Google) <[email protected]>
>
> Reviewed-by: Davidlohr Bueso <[email protected]>
Thank you!
> >---
> > kernel/locking/locktorture.c | 12 +++++++-----
> > 1 file changed, 7 insertions(+), 5 deletions(-)
> >
> >diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
> >index 8968fd65a90d..b64a528e511c 100644
> >--- a/kernel/locking/locktorture.c
> >+++ b/kernel/locking/locktorture.c
> >@@ -48,6 +48,7 @@ torture_param(int, stat_interval, 60,
> > torture_param(int, stutter, 5, "Number of jiffies to run/halt test, 0=disable");
> > torture_param(int, rt_boost, 2,
> > "Do periodic rt-boost. 0=Disable, 1=Only for rt_mutex, 2=For all lock types.");
> >+torture_param(int, rt_boost_factor, 50, "A factor determining how often rt-boost happens.");
> > torture_param(int, verbose, 1,
> > "Enable verbose debugging printk()s");
> > torture_param(int, nlocks, 1,
> >@@ -133,12 +134,12 @@ static void torture_lock_busted_write_unlock(int tid __maybe_unused)
> >
> > static void __torture_rt_boost(struct torture_random_state *trsp)
> > {
> >- const unsigned int factor = 50000; /* yes, quite arbitrary */
> >+ const unsigned int factor = rt_boost_factor;
> >
> > if (!rt_task(current)) {
> > /*
> >- * Boost priority once every ~50k operations. When the
> >- * task tries to take the lock, the rtmutex it will account
> >+ * Boost priority once every rt_boost_factor operations. When
> >+ * the task tries to take the lock, the rtmutex it will account
>
> Nit: maybe refer to it as 'rt_boost_factor'?
Sorry, I did not follow. Refer to what?
thanks,
- Joel
>
> > * for the new priority, and do any corresponding pi-dance.
> > */
> > if (trsp && !(torture_random(trsp) %
> >@@ -148,8 +149,9 @@ static void __torture_rt_boost(struct torture_random_state *trsp)
> > return;
> > } else {
> > /*
> >- * The task will remain boosted for another ~500k operations,
> >- * then restored back to its original prio, and so forth.
> >+ * The task will remain boosted for another 10*rt_boost_factor
> >+ * operations, then restored back to its original prio, and so
> >+ * forth.
> > *
> > * When @trsp is nil, we want to force-reset the task for
> > * stopping the kthread.
> >--
> >2.39.0.rc1.256.g54fd8350bd-goog
> >
On Fri, 09 Dec 2022, Joel Fernandes wrote:
>> >- * Boost priority once every ~50k operations. When the
>> >- * task tries to take the lock, the rtmutex it will account
>> >+ * Boost priority once every rt_boost_factor operations. When
>> >+ * the task tries to take the lock, the rtmutex it will account
>>
>> Nit: maybe refer to it as 'rt_boost_factor'?
>
>Sorry, I did not follow. Refer to what?
Just use single quotes to refer to the parameter.
Thanks,
Davidlohr
On Fri, Dec 9, 2022 at 10:56 PM Davidlohr Bueso <[email protected]> wrote:
>
> On Fri, 09 Dec 2022, Joel Fernandes wrote:
>
> >> >- * Boost priority once every ~50k operations. When the
> >> >- * task tries to take the lock, the rtmutex it will account
> >> >+ * Boost priority once every rt_boost_factor operations. When
> >> >+ * the task tries to take the lock, the rtmutex it will account
> >>
> >> Nit: maybe refer to it as 'rt_boost_factor'?
> >
> >Sorry, I did not follow. Refer to what?
>
> Just use single quotes to refer to the parameter.
Ah, got it. Will do (either next respin or Paul can do it) and thank you.
- Joel