On Wed, Nov 19 2008, Martin Peschke wrote: > Hi, > > I run across blktrace complaints about broken traces once in a while. > I have pimped up the debugging output in verify_trace(): > > --- bad trace magic --- > magic 0x00000000 > sequence 0x00000000 > time 0x0000000000000000 > sector 0x0000000000000000 > bytes 0x65617407 <--- begin of trace (trace magic) > action 0x000005b0 > pid 0x0000029c > device 0x7c185ac0 > cpu 0x00000000 > error 0x0036 > pdu_len 0x18c0 > > 00000000 00000000 00000000 00000000 00000000 00000000 > 65617407 000005b0 0000029c 7c185ac0 00000000 003618c0 > > bad trace in /sys/kernel/debug/block/sdbm/trace1 > > Traces appear to get out of place by some bytes. The offset varies. > > > I have got a couple of questions: > > Does blktrace stop processing of a trace stream in this case, doesn't > it? > > Next I am going to dump the trace which precedes a broken trace. > Any better ideas how to debug this one? I think Alan and I debugged something like this in the early days of blktrace. Is your stream consistently off when this happens? Does the sequence numbers jump? The most likely culprit is a relay bug, and there's recently been some fixing for that. -- Jens Axboe -- 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
