On Wed, 2008-11-19 at 13:44 +0100, Jens Axboe wrote: > How are you running blktrace? blktrace -a issue -a drv_data -a complete -w 43200 -o - /dev/sda ... /dev/sdz | blkiomon > If you have the blktrace output files, you > can inspect what it would have done next. I am concerned about pdu_len being some random number then. I don't think blktrace would find a valid trace after taking a random number of bytes for a trace payload. > > Sequence numbers appear to jump, from 183e8 to f1b1 in this case: > > > > --- bad trace magic --- > > magic 0x00000001 > > sequence 0x0001007a > > time 0x000000000000fb40 > > sector 0x000000000005925e > > bytes 0x65617407 > > action 0x0000f1b1 > > pid 0x00000773 > > device 0xec86baa8 > > cpu 0x00000000 > > error 0x007f > > pdu_len 0x8430 > > > > 00000001 0001007a 00000000 0000fb40 00000000 0005925e 65617407 0000f1b1 > > 00000773 ec86baa8 00000000 007f8430 > > So that's interesting. What byte offset did this happen at? And what is > your subbuffer size for blktrace? see tip_subbuf output (from flush_subbuf_file()) below --- bad trace magic --- magic 0x00017000 sequence 0x40010011 time 0x0000346f04100080 sector 0x0000000100000018 bytes 0x00000001 action 0x00010080 pid 0x00000000 device 0x0000bbea cpu 0x00000000 error 0x0014 pdu_len 0x8d98 00017000 40010011 0000346f 04100080 00000001 00000018 00000001 00010080 00000000 0000bbea 00000000 00148d98 bad trace in /sys/kernel/debug/block/sdy/trace1 ts->buf 0x2004c5027c0, ts->len 0x108, ts->max_len 0x80000, offset 0x48, t 0x2004c502808 --- previous trace --- magic 0x65617407 sequence 0x0001a232 time 0x00000e5bb87cd096 sector 0x0000000000843c08 bytes 0x00001000 action 0x40010011 pid 0x00003467 device 0x04100080 cpu 0x00000001 error 0x0000 pdu_len 0x0018 65617407 0001a232 00000e5b b87cd096 00000000 00843c08 00001000 40010011 00003467 04100080 00000001 00000018 --- bad trace magic --- magic 0x00001000 sequence 0x09410007 time 0x00003469008000c0 sector 0x0000000000000000 bytes 0x65617407 action 0x0000fae2 pid 0x00000e44 device 0xbbefaa91 cpu 0x00000000 error 0x008f pdu_len 0xd358 00001000 09410007 00003469 008000c0 00000000 00000000 65617407 0000fae2 00000e44 bbefaa91 00000000 008fd358 bad trace in /sys/kernel/debug/block/sdm/trace0 ts->buf 0x20060280910, ts->len 0xc00, ts->max_len 0x80000, offset 0xf0, t 0x20060280a00 --- previous trace --- magic 0x65617407 sequence 0x0000fadd time 0x65617407000067d8 sector 0x00000d9ba13e3b74 bytes 0x00000000 action 0x00500030 pid 0x00001000 device 0x40010011 cpu 0x00003466 error 0x0080 pdu_len 0x00c0 65617407 0000fadd 65617407 000067d8 00000d9b a13e3b74 00000000 00500030 00001000 40010011 00003466 008000c0 -- To unsubscribe from this list: send the line "unsubscribe linux-btrace" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
