Re: [PATCH 0/7] nvme: export additional diagnostic counters via sysfs

Hannes Reinecke
2026-02-02T22:56:43Z

On 1/30/26 19:20, Nilay Shroff wrote:
> Hi,
>
> The NVMe driver encounters various events and conditions during normal
> operation that are either not tracked today or not exposed to userspace
> via sysfs. Lack of visibility into these events can make it difficult to
> diagnose subtle issues related to controller behavior, multipath
> stability, and I/O reliability.
>
> This patchset adds several diagnostic counters that provide improved
> observability into NVMe behavior. These counters are intended to help
> users understand events such as transient path unavailability,
> controller retries/reconnect/reset, failovers, and I/O failures. They
> can also be consumed by monitoring tools such as nvme-top.
>
> Specifically, this series proposes to export the following counters via
> sysfs:
> - Command retry count
> - Multipath failover count
> - Command error count
> - I/O requeue count
> - I/O failure count
> - Controller reset event counts
> - Controller reconnect counts
>
> The patchset consists of seven patches:
> Patch 1: Export command retry count
> Patch 2: Export multipath failover count
> Patch 3: Export command error count
> Patch 4: Export I/O requeue count
> Patch 5: Export I/O failure count
> Patch 6: Export controller reset event counts
> Patch 7: Export controller reconnect event count
>
> Please note that this patchset doesn't make any functional change but
> rather export relevant counters to user space via sysfs.
>
> As usual, feedback/comments/suggestions are welcome!
>

While I do agree with the general idea, I do wonder whether debugfs
would not be a better suited place for all of this. Having all of
this information in sysfs will clutter is by quite a bit, plus we
do have the usual issues with ABI stability if we ever see the need
to change (or, heaven forbid, remove) any of these counters.

(And when doing so it might be an idea to add a 'version' entry
to debugfs such that we can manage userspace expectation).

Cheers,

Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@suse.de +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich