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Message-ID: <x49tyh5c4v2.fsf@segfault.boston.devel.redhat.com> Date: Wed, 19 Jan 2011 10:04:01 -0500 From: Jeff Moyer <jmoyer@...hat.com> To: Jens Axboe <axboe@...nel.dk> Cc: Tao Ma <tm@....ma>, linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org> Subject: Re: [PATCH v2] blktrace: Don't output messages if NOTIFY isn't set. Jens Axboe <axboe@...nel.dk> writes: > On 2011-01-18 23:09, Tao Ma wrote: >> On 01/19/2011 01:36 PM, Jens Axboe wrote: >>> On 2011-01-18 20:09, Tao Ma wrote: >>>> Hi Jeff, >>>> On 01/18/2011 11:50 PM, Jeff Moyer wrote: >>>>> Tao Ma<tm@....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@...bao.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@...nel.dk> >>>> Cc: Steven Rostedt<rostedt@...dmis.org> >>>> Cc: Jeff Moyer<jmoyer@...hat.com> >>>> Signed-off-by: Tao Ma<boyu.mt@...bao.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. >> uh, yes, that's the reason why I put the check in __trace_note_message, >> not in trace_note. trace_note_time and trace_note_tsk will handle >> time/task issue and then call trace_note with the appropriate action >> mask. Do I miss something here? > > You did, I missed that. Patch looks fine then, I'll queue it up. Thanks! I was guessing at the use of BLK_TC_NOTIFY for this. Should there be another flag for these messages, so they aren't conflated with task/timestamp notifications? Cheers, Jeff -- 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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