Messages in this thread | | | Date | Fri, 7 Feb 2020 08:26:35 -0500 | From | Joel Fernandes <> | Subject | Re: [PATCH v1 1/1] binder: transaction latency tracking for user build |
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On Fri, Feb 07, 2020 at 02:28:59PM +0800, Frankie Chang wrote: > On Thu, 2020-02-06 at 22:17 -0500, Joel Fernandes wrote: > > On Fri, Feb 07, 2020 at 11:10:23AM +0800, Frankie Chang wrote: > > > On Wed, 2020-02-05 at 10:49 -0500, Joel Fernandes wrote: > > > > On Wed, Feb 05, 2020 at 09:36:12AM +0000, Greg Kroah-Hartman wrote: > > > > > On Wed, Feb 05, 2020 at 02:52:52PM +0800, Frankie Chang wrote: > > > > > > Record start/end timestamp to binder transaction. > > > > > > When transaction is completed or transaction is free, > > > > > > it would be checked if transaction latency over threshold (2 sec), > > > > > > if yes, printing related information for tracing. > > > > > > > > > > > > Signed-off-by: Frankie Chang <Frankie.Chang@mediatek.com> > > > > > > --- > > > > > > drivers/android/Kconfig | 8 +++ > > > > > > drivers/android/binder.c | 107 +++++++++++++++++++++++++++++++++++++ > > > > > > drivers/android/binder_internal.h | 4 ++ > > > > > > 3 files changed, 119 insertions(+) > > > > > > > > > > > > diff --git a/drivers/android/Kconfig b/drivers/android/Kconfig > > > > > > index 6fdf2ab..7ba80eb 100644 > > > > > > --- a/drivers/android/Kconfig > > > > > > +++ b/drivers/android/Kconfig > > > > > > @@ -54,6 +54,14 @@ config ANDROID_BINDER_IPC_SELFTEST > > > > > > exhaustively with combinations of various buffer sizes and > > > > > > alignments. > > > > > > > > > > > > +config BINDER_USER_TRACKING > > > > > > + bool "Android Binder transaction tracking" > > > > > > + help > > > > > > + Used for track abnormal binder transaction which is over 2 seconds, > > > > > > + when the transaction is done or be free, this transaction would be > > > > > > + checked whether it executed overtime. > > > > > > + If yes, printing out the detail info about it. > > > > > > + > > > > > > endif # if ANDROID > > > > > > > > > > > > endmenu > > > > > > diff --git a/drivers/android/binder.c b/drivers/android/binder.c > > > > > > index e9bc9fc..5a352ee 100644 > > > > > > --- a/drivers/android/binder.c > > > > > > +++ b/drivers/android/binder.c > > > > > > @@ -76,6 +76,11 @@ > > > > > > #include "binder_internal.h" > > > > > > #include "binder_trace.h" > > > > > > > > > > > > +#ifdef CONFIG_BINDER_USER_TRACKING > > > > > > +#include <linux/rtc.h> > > > > > > +#include <linux/time.h> > > > > > > +#endif > > > > > > + > > > > > > static HLIST_HEAD(binder_deferred_list); > > > > > > static DEFINE_MUTEX(binder_deferred_lock); > > > > > > > > > > > > @@ -591,8 +596,104 @@ struct binder_transaction { > > > > > > * during thread teardown > > > > > > */ > > > > > > spinlock_t lock; > > > > > > +#ifdef CONFIG_BINDER_USER_TRACKING > > > > > > + struct timespec timestamp; > > > > > > + struct timeval tv; > > > > > > +#endif > > > > > > }; > > > > > > > > > > > > +#ifdef CONFIG_BINDER_USER_TRACKING > > > > > > + > > > > > > +/* > > > > > > + * binder_print_delay - Output info of a delay transaction > > > > > > + * @t: pointer to the over-time transaction > > > > > > + */ > > > > > > +static void binder_print_delay(struct binder_transaction *t) > > > > > > +{ > > > > > > + struct rtc_time tm; > > > > > > + struct timespec *startime; > > > > > > + struct timespec cur, sub_t; > > > > > > + > > > > > > + ktime_get_ts(&cur); > > > > > > + startime = &t->timestamp; > > > > > > + sub_t = timespec_sub(cur, *startime); > > > > > > + > > > > > > + /* if transaction time is over than 2 sec, > > > > > > + * show timeout warning log. > > > > > > + */ > > > > > > + if (sub_t.tv_sec < 2) > > > > > > + return; > > > > > > + > > > > > > + rtc_time_to_tm(t->tv.tv_sec, &tm); > > > > > > + > > > > > > + spin_lock(&t->lock); > > > > > > + pr_info_ratelimited("%d: from %d:%d to %d:%d", > > > > > > + t->debug_id, > > > > > > + t->from ? t->from->proc->pid : 0, > > > > > > + t->from ? t->from->pid : 0, > > > > > > + t->to_proc ? t->to_proc->pid : 0, > > > > > > + t->to_thread ? t->to_thread->pid : 0); > > > > > > + spin_unlock(&t->lock); > > > > > > + > > > > > > + pr_info_ratelimited(" total %u.%03ld s code %u start %lu.%03ld android %d-%02d-%02d %02d:%02d:%02d.%03lu\n", > > > > > > + (unsigned int)sub_t.tv_sec, > > > > > > + (sub_t.tv_nsec / NSEC_PER_MSEC), > > > > > > + t->code, > > > > > > + (unsigned long)startime->tv_sec, > > > > > > + (startime->tv_nsec / NSEC_PER_MSEC), > > > > > > + (tm.tm_year + 1900), (tm.tm_mon + 1), tm.tm_mday, > > > > > > + tm.tm_hour, tm.tm_min, tm.tm_sec, > > > > > > + (unsigned long)(t->tv.tv_usec / USEC_PER_MSEC)); > > > > > > +} > > > > > > > > > > Ick, why not use a tracepoint for this instead? > > > > > > > > > > And what is userspace supposed to do with this if they see it? > > > > > > > > Or another option is to implement this separately outside of binder.c using > > > > register_trace_* on the existing binder tracepoints, similar to what say the > > > > block tracer or preempt-off tracers do. Call it, say, "binder-latency tracer". > > > > > > > > That way all of this tracing code is in-kernel but outside of binder.c. > > > > > > > > thanks, > > > > > > > > - Joel > > > > > > > Time limitation of recording is the reason why we don't use tracepoint. > > > In some situations, the exception is caused by a series of transactions > > > interaction. > > > Some abnormal transactions may be pending for a long time ago, they > > > could not be recorded due to buffer limited. > > > > register_trace_* does not use the trace buffer so I am not sure what you > > mean. I am asking you to use tracepoints, not ftrace events. > > > > thanks, > > > > - Joel > > > The existing binder tracepoint may not be precise enough because there > is no proper tracepoint which can represent the real finished time of > transaction.
May be you can add such TP then?
> The reason why we don't put the code outside binder.c is that structure > of binder_transaction didn't put in header file. > If it could be moved to binder_internal.h, then we can add > "binder-latency tracer" as you mentioned earlier.
That should be doable.
The reason I don't like custom tracing logic in core files as your patch is doing, is that it is doubtful if a lot of people would use it to warrant adding into a core file. In this case, probably a separate tracer (outside of binder.c) is a better option so as to not pollute the core files.
thanks,
- Joel
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