From: Tao Ma <boyu.mt@xxxxxxxxxx> With the newest kernel(say 2.6.37, some older one should also have the similar problem), some cfq messages are added to blktrace, so it makes the old blkparse broken. See a simple example: 1. blktrace /dev/sdb -o -|blkparse -i - 2. Run the following command(/dev/sdb1 is mounted at /mnt/test_dir): dd if=/mnt/test_dir/test of=/dev/null bs=4k count=1 iflag=direct There are only 2 lines of output there: 8,16 0 1 0.000000000 13183 A R 114759 + 8 <- (8,17) 114696 8,16 0 2 0.000000491 13183 Q R 114759 + 8 [dd] And even we run a command line like: for((i=0;i<100;i++))do dd if=/mnt/ocfs2/test of=/dev/null bs=4k count=1 iflag=direct;done We are only given the same 2 lines of output. While the really one should look like: 8,16 0 1 0.000000000 13319 A R 114759 + 8 <- (8,17) 114696 8,16 0 2 0.000000376 13319 Q R 114759 + 8 [dd] 8,16 0 0 0.000005931 0 m N cfq13319 alloced 8,16 0 3 0.000006259 13319 G R 114759 + 8 [dd] 8,16 0 4 0.000007143 13319 P N [dd] 8,16 0 5 0.000007817 13319 I R 114759 + 8 [dd] 8,16 0 0 0.000008491 0 m N cfq13319 insert_request 8,16 0 0 0.000009029 0 m N cfq13319 add_to_rr ... The main reason is that in show_entries_rb, we test sequences every time, but actually with some messages like cfq, the sequence number is always 0 which makes the old sequence check refuses all the logs after it. So only check/store sequence number if it isn't a message. Cc: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Tao Ma <boyu.mt@xxxxxxxxxx> --- blkparse.c | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-) diff --git a/blkparse.c b/blkparse.c index da34c14..c911185 100644 --- a/blkparse.c +++ b/blkparse.c @@ -2065,7 +2065,8 @@ static void show_entries_rb(int force) break; } - if (check_sequence(pdi, t, force)) + if (!(bit->action == BLK_TN_MESSAGE) && + check_sequence(pdi, t, force)) break; if (!force && bit->time > last_allowed_time) @@ -2076,7 +2077,8 @@ static void show_entries_rb(int force) if (!pci || pci->cpu != bit->cpu) pci = get_cpu_info(pdi, bit->cpu); - pci->last_sequence = bit->sequence; + if (!(bit->action == BLK_TN_MESSAGE)) + pci->last_sequence = bit->sequence; pci->nelems++; -- 1.6.3.GIT -- 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
