On 8/6/21 2:55 am, David Sterba wrote:

On Sat, Jun 05, 2021 at 06:38:16AM +0800, Anand Jain wrote:

quoted

On 04/06/2021 22:21, David Sterba wrote:

quoted

On Fri, Jun 04, 2021 at 09:41:09PM +0800, Anand Jain wrote:

quoted

On 4/6/21 9:20 pm, David Sterba wrote:

quoted

The device stats can be read by ioctl, wrapped by command 'btrfs device
stats'. Provide another source where to read the information in
/sys/fs/btrfs/FSID/devinfo/DEVID/stats .

    The planned stat here is errors stat.
    So why not rename this to error_stats?

I think it's commonly called device stats, dev stats, so when it's in
'devinfo' it's like it's the 'stats' for the device.

quoted

We don't have other
stats, like regarding io but in that case it would make sense to
distnguish the names.

My read_policy work (which I suppose is next on your list for review)

Yeah, it's among the next things to merge once the current features
stabilize enough.

quoted

made sense that publishing the io-stat information locally from btrfs is
a good idea. So that it provides clarity if the IO is skewed to a device
or balanced. Which is even more essential in the case of mixed device
types. For now IMHO,  /sys/fs/btrfs/FSID/devinfo/DEVID/error_stats
is harmless.

Agreed, I thought about the same, gathering some regular io stats, so
the error_stats makes sense.  > There's still one open question whether to
do it all in one file or in a subdirectory error_stats/ . > The sysfs way
is one value per file but for the stats

I'm more inclined to follow what
/proc/ stats do. It's more convenient to monitor stats in one file read
than having to do 'cat error_stats/*' or with filenames as 'grep ^
error_stats/*'.

  Agreed. I prefer one file from the convenience pov. Also, block dev has
  one file, the reason to represent it invariably at a given time [1]
    [1] https://www.kernel.org/doc/Documentation/block/stat.txt
  IMO the same applies to btrfs too.

Thanks, Anand