Messages in this thread | | | Date | Wed, 19 Jan 2011 06:43:32 -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 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@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. > 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!
-- Jens Axboe
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