Messages in this thread | | | Date | Tue, 18 Jan 2011 22:36:51 -0700 | From | Jens Axboe <> | Subject | Re: [PATCH v2] blktrace: Don't output messages if NOTIFY isn't set. |
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On 2011-01-18 20:09, Tao Ma wrote: > Hi Jeff, > On 01/18/2011 11:50 PM, Jeff Moyer wrote: >> Tao Ma<tm@tao.ma> writes: >> >>> + /* >>> + * If the user does specify some action masks, don't send any note >>> + * message to the trace so that it won't pollute what the user really >>> + * want to see. >>> + */ >>> + if (bt->act_mask != (u16) -1) >>> + return; >>> + >> >> I think you want to check for the BLK_TC_NOTIFY bit. > I was thinking of this, but actually there is no way for the user to set this flag. > At least from blktrace(8), -a doesn't have any flags like NOTIFY. So if the user > set any flag, NOTIFY will be cleared. So it does work. Thanks. > > Here is the updated patch. > > From 8693c19f165b09f60d5c26aed369d79a79e144ba Mon Sep 17 00:00:00 2001 > From: Tao Ma <boyu.mt@taobao.com> > Date: Wed, 19 Jan 2011 10:51:44 +0800 > Subject: [PATCH v2] blktrace: Don't output messages if NOTIFY isn't set. > > Now if we enable blktrace, cfq has too many messages output to the > trace buffer. It is fine if we don't specify any action mask. > But if I do like this: > blktrace /dev/sdb -a issue -a complete -o - | blkparse -i - > I only want to see 'D' and 'C', while with the following command > dd if=/mnt/ocfs2/test of=/dev/null bs=4k count=1 iflag=direct > > I will get(with a 2.6.37 vanilla kernel): > 8,16 0 0 0.000000000 0 m N cfq3805 alloced > 8,16 0 0 0.000004126 0 m N cfq3805 insert_request > 8,16 0 0 0.000004884 0 m N cfq3805 add_to_rr > 8,16 0 0 0.000008417 0 m N cfq workload slice:300 > 8,16 0 0 0.000009557 0 m N cfq3805 set_active wl_prio:0 wl_type:2 > 8,16 0 0 0.000010640 0 m N cfq3805 fifo= (null) > 8,16 0 0 0.000011193 0 m N cfq3805 dispatch_insert > 8,16 0 0 0.000012221 0 m N cfq3805 dispatched a request > 8,16 0 0 0.000012802 0 m N cfq3805 activate rq, drv=1 > 8,16 0 1 0.000013181 3805 D R 114759 + 8 [dd] > 8,16 0 2 0.000164244 0 C R 114759 + 8 [0] > 8,16 0 0 0.000167997 0 m N cfq3805 complete rqnoidle 0 > 8,16 0 0 0.000168782 0 m N cfq3805 set_slice=100 > 8,16 0 0 0.000169874 0 m N cfq3805 arm_idle: 8 group_idle: 0 > 8,16 0 0 0.000170189 0 m N cfq schedule dispatch > 8,16 0 0 0.000397938 0 m N cfq3805 slice expired t=0 > 8,16 0 0 0.000399763 0 m N cfq3805 sl_used=1 disp=1 charge=1 iops=0 sect=8 > 8,16 0 0 0.000400227 0 m N cfq3805 del_from_rr > 8,16 0 0 0.000400882 0 m N cfq3805 put_queue > > See, there are 19 lines while I only need 2. I don't think it is > appropriate for a user. > > So this patch will disable any messages if the BLK_TC_NOTIFY isn't set. > Now the output for the same command will look like: > 8,16 0 1 0.000000000 4908 D R 114759 + 8 [dd] > 8,16 0 2 0.000146827 0 C R 114759 + 8 [0] > > Yes, it is what I want to see. > > Cc: Jens Axboe <axboe@kernel.dk> > Cc: Steven Rostedt <rostedt@goodmis.org> > Cc: Jeff Moyer <jmoyer@redhat.com> > Signed-off-by: Tao Ma <boyu.mt@taobao.com> > --- > kernel/trace/blktrace.c | 7 +++++++ > 1 files changed, 7 insertions(+), 0 deletions(-) > > diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c > index 153562d..d95721f 100644 > --- a/kernel/trace/blktrace.c > +++ b/kernel/trace/blktrace.c > @@ -138,6 +138,13 @@ void __trace_note_message(struct blk_trace *bt, const char *fmt, ...) > !blk_tracer_enabled)) > return; > > + /* > + * If the BLK_TC_NOTIFY action mask isn't set, don't send any note > + * message to the trace. > + */ > + if (!(bt->act_mask & BLK_TC_NOTIFY)) > + return; > + > local_irq_save(flags); > buf = per_cpu_ptr(bt->msg_data, smp_processor_id()); > va_start(args, fmt);
Hmm, it should only mask messages, not task/timestamp notifies. This will mask all of them.
The message mask I agree with, but the other ones should essentially be unmaskable.
-- Jens Axboe
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