Re: [Crash-utility] [PATCH v2] Handle blk_mq_ctx member changes for kernels v5.16-rc1~75^2~44
Hi, Steffen and Kazu
Sorry, I missed this information.
On Tue, Jan 4, 2022 at 9:10 AM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab(a)nec.com>
wrote:
-----Original Message-----
> Admittedly, I haven't looked into the details, but those simple numbers
for
> pending IO have been very valuable for me, when analyzing dumps with
> dm-multipath over (FC-attached) SCSI disks. Aren't those pending IO
numbers
> available elsewhere in the kernel? Maybe not in debugfs anymore, but I
suppose
> the (mq) block layer does keep track of them?
AFAIK, unfortunately there is no simple counter, crash needs to parse
sbitmap
structures to count them. (please let us know if there is a simpler
solution.)
Currently Sergey has worked on adding sbitmap function [1], and we plan to
make
use of it after merging the patch. It may take some time, so Lianbo's
patch is
a temporary workaround for the error.
In addition, I would like to add that the counter for the
ctx->rq_completed/ctx->rq_dispatched(for 'dev -d') may become inaccurate
due to racing per-cpu values in the kernel. I'm considering whether crash
should print a warning or "not supported" for "dev -d", which can
avoid
misleading users. So far we have encountered two similar cases.
What's your opinion?Kazu.
BTW: Also added IIya to cc list.
Thanks.
Lianbo
Maybe it was better to write the status on the commit log..
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