Re: [RFC PATCHv4 5/6] nvme-multipath: add debugfs attribute adaptive_weight_timeout

Hannes Reinecke
2025-11-04T14:58:39Z

On 11/4/25 11:45, Nilay Shroff wrote:
> By default, the adaptive I/O policy accumulates latency samples over a
> 15-second window. When this window expires, the driver computes the
> average latency and updates the smoothed (EWMA) latency value. The
> path weight is then recalculated based on this data.
>
> A 15-second window provides a good balance for most workloads, as it
> helps smooth out transient latency spikes and produces a more stable
> path weight profile. However, some workloads may benefit from faster
> or slower adaptation to changing latency conditions.
>
> This commit introduces a new debugfs attribute, adaptive_weight_timeout,
> which allows users to configure the path weight calculation interval
> based on their workload requirements.
>
> Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
> ---
> drivers/nvme/host/core.c | 1 +
> drivers/nvme/host/debugfs.c | 40 ++++++++++++++++++++++++++++++++++-
> drivers/nvme/host/multipath.c | 7 ++++--
> drivers/nvme/host/nvme.h | 1 +
> 4 files changed, 46 insertions(+), 3 deletions(-)
>
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
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