Re: [PATCH v1] rt-tests: hwlatdetect: Add timestamp delta

[John Kacur <jkacur@gmail.com>]

On Mon, 2 Mar 2026, Costa Shulyupin wrote:

> Add delta field that calculates the time interval between consecutive
> samples. For the first sample, the previous timestamp is initialized to
> 'nan' (Not a Number), so the first delta is also 'nan'.
> 
> This helps identify periodic issues during hardware latency testing.
> 
> Signed-off-by: Costa Shulyupin <costa.shul@redhat.com>
> ---
>  src/hwlatdetect/hwlatdetect.py | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/src/hwlatdetect/hwlatdetect.py b/src/hwlatdetect/hwlatdetect.py
> index 42b9f301718a..f95e771048f6 100755
> --- a/src/hwlatdetect/hwlatdetect.py
> +++ b/src/hwlatdetect/hwlatdetect.py
> @@ -253,7 +253,8 @@     def detect(self):
>  
>      class Sample:
>          'private class for tracer sample data'
> -        __slots__ = 'cpu', 'timestamp', 'inner', 'outer', 'count'
> +        __slots__ = 'cpu', 'timestamp', 'delta', 'inner', 'outer', 'count'
> +        prev = 'nan'

	prev = float('nan')


>  
>          def __init__(self, line):
>              fields = line.split()
> @@ -276,14 +277,15 @@         def __init__(self, line):
>              i, o = fields[6].split('/')
>              ts = fields[7][3:]
>              self.timestamp = str(ts)
		ts_float = float(ts)

> +            self.delta = float(ts) - float(self.__class__.prev)
		self.delta = ts_float - self.__class__.prev
> +            self.__class__.prev = ts
		self.__class__.prev = ts_float
>              self.inner = int(i)
>              self.outer = int(o)
>              self.count = int(kv["count"]) if "count" in kv else None
>  
>          def __str__(self):
> -            if self.count is not None:
> -                return f"ts: {self.timestamp}, inner:{self.inner}, outer:{self.outer}, cpu:{self.cpu}, count:{self.count}"
> -            return f"ts: {self.timestamp}, inner:{self.inner}, outer:{self.outer}, cpu:{self.cpu}"
> +            s = f"ts: {self.timestamp}, delta:{self.delta:.6f}, inner:{self.inner}, outer:{self.outer}, cpu:{self.cpu}"
> +            return s if self.count is None else s + f", count:{self.count}"
>  
>          def display(self):
>              """ convert object to string and print """
> -- 
> 2.53.0
> 
> 
>