On Mon, Apr 12, 2021 at 7:35 AM Jinpu Wang [off-list ref] wrote:

On Fri, Apr 9, 2021 at 11:03 PM Jens Axboe [off-list ref] wrote:

quoted

On 4/9/21 10:03 AM, Md Haris Iqbal wrote:

quoted

Hi Jens,

This version fixes the long lines in the code as per Christoph's comment.

I'd really like to see some solid justification for the addition,
though. I clicked the v1 link and it's got details on what you get out
of it, but not really the 'why' of reasoning for the feature. I mean,
you could feasibly have a blktrace based userspace solution. Just
wondering if that has been tried, I know that's what we do at Facebook
for example.

Hi Jens,

Thanks for the reply.
For the use case of the additional stats, as a cloud provider, we
often need to handle report from the customers regarding
performance problem in a period of time in the past, so it's not
feasible for us to run blktrace, customer workload could change from
time to time, with the additional stats, we gather through all metrics
using Prometheus, we can navigate to the period of time interested,
to check if the performance matches the SLA, it also helps us to find
the user IO pattern,  we can more easily reproduce.

We do use blktrace from time to time too if it's not too late (when IO
pattern has not changed.)

Thanks!
Jack

Hi Jens,

A gentle ping!