Re: [PATCH] migration/postcopy: Add latency distribution report for blocktime

[Peter Xu <peterx@redhat.com>]

On Mon, Jun 09, 2025 at 06:36:07PM -0400, Peter Xu wrote:
> Add the latency distribution too for blocktime, using order-of-two buckets.
> It accounts for all the faults, from either vCPU or non-vCPU threads.  With
> prior rework, it's very easy to achieve by adding an array to account for
> faults in each buckets.
> 
> Sample output for HMP (while for QMP it's simply an array):
> 
> Postcopy Latency Distribution:
>   [     1 us -     2 us ]:          0
>   [     2 us -     4 us ]:          0
>   [     4 us -     8 us ]:          1
>   [     8 us -    16 us ]:          2
>   [    16 us -    32 us ]:          2
>   [    32 us -    64 us ]:          3
>   [    64 us -   128 us ]:      10169
>   [   128 us -   256 us ]:      50151
>   [   256 us -   512 us ]:      12876
>   [   512 us -     1 ms ]:         97
>   [     1 ms -     2 ms ]:         42
>   [     2 ms -     4 ms ]:         44
>   [     4 ms -     8 ms ]:         93
>   [     8 ms -    16 ms ]:        138
>   [    16 ms -    32 ms ]:          0
>   [    32 ms -    65 ms ]:          0
>   [    65 ms -   131 ms ]:          0
>   [   131 ms -   262 ms ]:          0
>   [   262 ms -   524 ms ]:          0
>   [   524 ms -    1 sec ]:          0
>   [    1 sec -    2 sec ]:          0
>   [    2 sec -    4 sec ]:          0
>   [    4 sec -    8 sec ]:          0
>   [    8 sec -   16 sec ]:          0
> 
> Cc: Dr. David Alan Gilbert <dave@treblig.org>
> Cc: Markus Armbruster <armbru@redhat.com>
> Signed-off-by: Peter Xu <peterx@redhat.com>

Just to keep a record, the new version of this patch is included here:

https://lore.kernel.org/all/20250613141217.474825-15-peterx@redhat.com/

There're trivial changes there, on marking the feature unstable, meanwhile
adjustments to suite the us->ns conversion suggested by Dave.

-- 
Peter Xu