08.03.2018 21:14, Vladimir Sementsov-Ogievskiy wrote:
08.03.2018 20:31, Eric Blake wrote:
On 03/06/2018 09:32 AM, Stefan Hajnoczi wrote:
On Wed, Feb 07, 2018 at 03:50:36PM +0300, Vladimir
Sementsov-Ogievskiy wrote:
Introduce latency histogram statics for block devices.
For each accounted operation type latency region [0, +inf) is
divided into subregions by several points. Then, calculate
hits for each subregion.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
---
According to Wikipedia and Mathworld, "intervals" and "bins" are
commonly used terms:
https://en.wikipedia.org/wiki/Histogram
http://mathworld.wolfram.com/Histogram.html
I suggest:
typedef struct {
/* The following histogram is represented like this:
*
* 5| *
* 4| *
* 3| * *
* 2| * * *
* 1| * * * *
* +------------------
* 10 50 100
*
* BlockLatencyHistogram histogram = {
* .nbins = 4,
* .intervals = {10, 50, 100},
* .bins = {3, 1, 5, 2},
* };
The name 'intervals' is still slightly ambiguous: does it hold the
boundary point (0-10 for 10 slots, 10-50 for 40 slots, 50-100, for 50
slots, then 100-INF) or is it the interval size of each slot (first
bin is 10 slots for 0-10, next bin is 50 slots wide so 10-60, next
bin is 100 slots wide so 60-160, everything else is 160-INF). But
the ascii-art diagram plus the text is sufficient to resolve the
intent if you keep that name (I don't have a suggestion for a better
name).
Hm. these numbers are actually boundary points of histogram intervals,
not intervals itself. And, wiki says "The bins are usually specified
as consecutive, non-overlapping intervals of a variable.", so,
intervals are bins.
So, what about:
1. interval_boundaries
2. bin_boundaries
3. boundaries
(and same names with s/_/-/ for qapi)
Also, now I doubt, is it a good idea to share same bin boundaries for
each io type.
--
Best regards,
Vladimir
