Hi, we recently ran into bio splitting problems in the kernel. A typical request would show up in the blktrace output as follows or worse: 253,2 8 23 0.041305439 4907 Q R 645838360 + 896 [dd] 253,2 8 24 0.041307791 4907 X R 645838360 / 645838872 [dd] 253,2 8 25 0.041308789 4907 X R 645838360 / 645838592 [dd] 253,2 8 26 0.041313578 4907 X R 645838872 / 645839104 [dd] 253,2 8 27 0.041319035 4907 X R 645838592 / 645838848 [dd] [...] 253,2 8 68 0.051036527 0 C R 645839104 + 152 ( 9731088) [0] The kernel bug leading to this kind of result (a split into 232-256-24-232-152 instead of 232-256-256-152) has meanwhile been fixed, but those kinds of traces remain difficult to read, for two reasons: first, it's hard to match a request to the corresponding completion because the sector and length of the completion don't match the request. Second, it's difficult to figure out which pieces a request is getting split into. I don't have a good answer to the second problem, but how about at least addressing the first problem by fixing up the sector and length of the completion to match the request in blkparse when --track-ios is used, as in the last of these three patches? The last line above would turn into: 253,2 8 68 0.051036527 0 C R 645838360 + 896 ( 9731088) [0] Thanks, Andreas Andreas Gruenbacher (3): blkparse: Fix device in event tracking error messages blkparse: Allow request tracking on non md/dm devices blkparse: Fix up the sector and length of split completions blkparse.c | 49 +++++++++++++++++++++++++++++++++++++------------ 1 file changed, 37 insertions(+), 12 deletions(-) base-commit: db4f6340e04716285ea56fe26d76381c3adabe58 -- 2.25.1
