From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Gruenbacher Date: Mon, 13 Apr 2020 19:01:48 +0000 Subject: [PATCH v2 0/4] Split io tracing Message-Id: <20200413190153.86357-1-agruenba@redhat.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-btrace@vger.kernel.org Hi, here's an update of the patches posted on April 6. 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 [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, the sector and length of the completion don't match the request. This isn't what it says in the blkparse manual page, it's hard to match a request to the corresponding completion, and it causes the statistics to be off as well. 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 this patch queue addresses the first problem by fixing up sector and length of split completions at least. The last line above would turn into: 253,2 8 68 0.051036527 0 C R 645838360 + 896 [0] Thanks, Andreas Andreas Gruenbacher (4): blkparse: Fix device in event tracking error messages blkparse: Allow request tracking on non md/dm devices blkparse: Initialize and test for undefined request tracking timestamps blkparse: Fix up the sector and length of split completions blkparse.c | 169 ++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 130 insertions(+), 39 deletions(-) base-commit: db4f6340e04716285ea56fe26d76381c3adabe58 -- 2.25.2