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Date: Tue, 15 Oct 2013 11:40:35 +0200 From: Jan Kara <jack@...e.cz> To: Jens Axboe <axboe@...nel.dk> Cc: LKML <linux-kernel@...r.kernel.org>, Jan Kara <jack@...e.cz> Subject: Re: [PATCH] blktrace: Send BLK_TN_PROCESS events to all running traces On Mon 23-09-13 13:37:23, Jan Kara wrote: > 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? Jens, ping? I guess this patch fell through cracks... Honza > > Signed-off-by: Jan Kara <jack@...e.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@...e.cz> > SUSE Labs, CR -- Jan Kara <jack@...e.cz> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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