configuration in commit 2724273e8fd00b512596a77ee063f49b25f36507,
titled "vmcore: add API to collect hardware dump in second kernel",
in which device drivers may collect a device specific snapshot of the
hardware/firmware state of their underlying devices, and export the
data as a kdump ELF note with type NT_VMCOREDD. This patch
recognizes the new ELF note(s) in both ELF and compressed kdump
vmcore dumpfiles. The "help -[nD]" option shows basic information
about each note, and two new "dev" command options have been
introduced. The "dev -V" option displays an indexed list of each
note, showing the device name, the dumpfile offset, and the size
of each note. The "dev -v index [file]" option either dumps the
contents of a note to the display screen in a human-readable format,
or copies the note data directly to a specified file.
(surendra@chelsio.com)
that contain commit 570d0200123fb4f809aa2f6226e93a458d664d70, titled
"driver core: move device->knode_class to device_private". Without
the patch, the command options fail with the error message "dev:
invalid structure member offset: device_knode_class".
(k-hagio@ab.jp.nec.com)
commit 7ff4f8035695984c513598e2d49c8277d5d234ca, titled "block:
remove dead queue members", in which the number of I/Os issued to
a disk driver are no longer stored in the request_queue structure.
Without the patch, the options indicate "dev: -d option not supported
or applicable on this architecture or kernel". With the patch, the
"DRV" column is not shown.
(m.mizuma@jp.fujitsu.com)
data on Linux 2.6.26 and later kernels. The option was deprecated
as of Linux 2.6.26, and without the patch, the option would indicate
"dev: -p option not supported or applicable on this architecture
or kernel" when running against the newer kernel versions. PCI Bus
information will also be displayed with this patch.
(m.mizuma@jp.fujitsu.com)
whose device driver uses the blk-mq interface. Currently "dev -d"
always displays 0 in all fields for the blk-mq disk because blk-mq
does not increment/decrement request_list.count[2] on I/O creation
and I/O completion. The following values are used in blk-mq in such
situations:
- I/O creation: blk_mq_ctx.rq_dispatched[2]
- I/O completion: blk_mq_ctx.rq_completed[2]
So, we can get the counter of in-progress I/Os as follows:
in progress I/Os == rq_dispatched - rq_completed
This patch displays the result of above calculation for the disk.
It determines whether the device driver uses blk-mq if the
request_queue.mq_ops is not NULL. The "DRV" field is displayed as
"N/A(MQ)" if the value for in-flight in the device driver does not
exist for blk-mq.
(m.mizuma@jp.fujitsu.com)
