Messages in this thread | | | Date | Mon, 23 Sep 2013 13:37:23 +0200 | From | Jan Kara <> | Subject | Re: [PATCH] blktrace: Send BLK_TN_PROCESS events to all running traces |
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On Tue 17-09-13 22:30:31, Jan Kara wrote: > Currently each task sends BLK_TN_PROCESS event to the first traced > device it interacts with after a new trace is started. When there are > several traced devices and the task accesses more devices, this logic > can result in BLK_TN_PROCESS being sent several times to some devices > while it is never sent to other devices. Thus blkparse doesn't display > command name when parsing some blktrace files. > > Fix the problem by sending BLK_TN_PROCESS event to all traced devices > when a task interacts with any of them. Jens, any opinion about this?
Honza
> > Signed-off-by: Jan Kara <jack@suse.cz> > --- > include/linux/blktrace_api.h | 2 ++ > kernel/trace/blktrace.c | 33 +++++++++++++++++++++++++++------ > 2 files changed, 29 insertions(+), 6 deletions(-) > > diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h > index 7c2e030..a12f6ed 100644 > --- a/include/linux/blktrace_api.h > +++ b/include/linux/blktrace_api.h > @@ -5,6 +5,7 @@ > #include <linux/relay.h> > #include <linux/compat.h> > #include <uapi/linux/blktrace_api.h> > +#include <linux/list.h> > > #if defined(CONFIG_BLK_DEV_IO_TRACE) > > @@ -23,6 +24,7 @@ struct blk_trace { > struct dentry *dir; > struct dentry *dropped_file; > struct dentry *msg_file; > + struct list_head running_list; > atomic_t dropped; > }; > > diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c > index b8b8560..7f727b3 100644 > --- a/kernel/trace/blktrace.c > +++ b/kernel/trace/blktrace.c > @@ -26,6 +26,7 @@ > #include <linux/export.h> > #include <linux/time.h> > #include <linux/uaccess.h> > +#include <linux/list.h> > > #include <trace/events/block.h> > > @@ -38,6 +39,9 @@ static unsigned int blktrace_seq __read_mostly = 1; > static struct trace_array *blk_tr; > static bool blk_tracer_enabled __read_mostly; > > +static LIST_HEAD(running_trace_list); > +static __cacheline_aligned_in_smp DEFINE_SPINLOCK(running_trace_lock); > + > /* Select an alternative, minimalistic output than the original one */ > #define TRACE_BLK_OPT_CLASSIC 0x1 > > @@ -107,10 +111,18 @@ record_it: > * Send out a notify for this process, if we haven't done so since a trace > * started > */ > -static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk) > +static void trace_note_tsk(struct task_struct *tsk) > { > + unsigned long flags; > + struct blk_trace *bt; > + > tsk->btrace_seq = blktrace_seq; > - trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, sizeof(tsk->comm)); > + spin_lock_irqsave(&running_trace_lock, flags); > + list_for_each_entry(bt, &running_trace_list, running_list) { > + trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, > + sizeof(tsk->comm)); > + } > + spin_unlock_irqrestore(&running_trace_lock, flags); > } > > static void trace_note_time(struct blk_trace *bt) > @@ -229,16 +241,15 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, > goto record_it; > } > > + if (unlikely(tsk->btrace_seq != blktrace_seq)) > + trace_note_tsk(tsk); > + > /* > * A word about the locking here - we disable interrupts to reserve > * some space in the relay per-cpu buffer, to prevent an irq > * from coming in and stepping on our toes. > */ > local_irq_save(flags); > - > - if (unlikely(tsk->btrace_seq != blktrace_seq)) > - trace_note_tsk(bt, tsk); > - > t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len); > if (t) { > sequence = per_cpu_ptr(bt->sequence, cpu); > @@ -477,6 +488,7 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev, > bt->dir = dir; > bt->dev = dev; > atomic_set(&bt->dropped, 0); > + INIT_LIST_HEAD(&bt->running_list); > > ret = -EIO; > bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt, > @@ -601,6 +613,9 @@ int blk_trace_startstop(struct request_queue *q, int start) > blktrace_seq++; > smp_mb(); > bt->trace_state = Blktrace_running; > + spin_lock_irq(&running_trace_lock); > + list_add(&bt->running_list, &running_trace_list); > + spin_unlock_irq(&running_trace_lock); > > trace_note_time(bt); > ret = 0; > @@ -608,6 +623,9 @@ int blk_trace_startstop(struct request_queue *q, int start) > } else { > if (bt->trace_state == Blktrace_running) { > bt->trace_state = Blktrace_stopped; > + spin_lock_irq(&running_trace_lock); > + list_del_init(&bt->running_list); > + spin_unlock_irq(&running_trace_lock); > relay_flush(bt->rchan); > ret = 0; > } > @@ -1472,6 +1490,9 @@ static int blk_trace_remove_queue(struct request_queue *q) > if (atomic_dec_and_test(&blk_probes_ref)) > blk_unregister_tracepoints(); > > + spin_lock_irq(&running_trace_lock); > + list_del(&bt->running_list); > + spin_unlock_irq(&running_trace_lock); > blk_trace_free(bt); > return 0; > } > -- > 1.8.1.4 > -- Jan Kara <jack@suse.cz> SUSE Labs, CR
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