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Date:   Wed, 5 Feb 2020 09:36:12 +0000
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Frankie Chang <Frankie.Chang@mediatek.com>
Cc:     Todd Kjos <tkjos@android.com>, Martijn Coenen <maco@android.com>,
        Arve =?iso-8859-1?B?SGr4bm5lduVn?= <arve@android.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Christian Brauner <christian@brauner.io>,
        linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org,
        wsd_upstream@mediatek.com, Jian-Min.Liu@mediatek.com
Subject: Re: [PATCH v1 1/1] binder: transaction latency tracking for user
 build
Message-ID: <20200205093612.GA1167956@kroah.com>
References: <1580885572-14272-1-git-send-email-Frankie.Chang@mediatek.com>
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In-Reply-To: <1580885572-14272-1-git-send-email-Frankie.Chang@mediatek.com>
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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?

thanks,

greg k-h