Re: [PATCH v3 05/10] sbitmap: add helpers for dumping to a seq_file

[Bart Van Assche <Bart.VanAssche@sandisk.com>]

On Wed, 2017-01-25 at 14:32 -0800, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
>=20
> This is useful debugging information that will be used in the blk-mq
> debugfs directory.
>=20
> Reviewed-by: Hannes Reinecke <hare@suse.com>
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
> Jens took offense to me making the bitmap dumps binary, so this turns the=
m into
> nicely formatted hex dumps, like this one:
>=20
> # cat /sys/kernel/debug/block/nvme0n1/mq/0/tags_bitmap
> 00000000: 0000 0000 0000 0000 0000 0000 0000 0000
> 00000010: 0000 2000 0000 0000 0000 0000 0000 0000
> 00000020: 0000 0000 0000 0000 0000 0000 0000 0000
> 00000030: 0000 0000 0000 0000 0000 0000 0000 0000
> 00000040: 0000 0000 0000 0000 0000 0000 0000 0000
> 00000050: 0000 0000 0000 0000 0000 0000 0000 0000
> 00000060: 0000 0000 0000 0000 0000 0000 0000 0000
> 00000070: 0000 0000 0000 0000 0000 0000 0000 0000
>=20
> I decided to go with this format because 1) it's consistent with
> print_hex_dump() already in the kernel, and 2) it's much easier to read
> than a string of bits or hex values. In the example above, it's easy to
> see that byte 0x12 is set to 0x20 (and do some arithmetic from there to
> figure out that the stuck bit is 149).

Hello Omar,

Have you considered to convert the bitmap into a contiguous bitmap first
and to format that bitmap with snprintf(..., "%*pb", ...)? I think that
will result in even easier to read output.

Bart.=