qemu-block
[Top][All Lists]

## Re: [Qemu-block] [Qemu-devel] [PATCH v2 1/2] block/accounting: introduce

 From: Vladimir Sementsov-Ogievskiy Subject: Re: [Qemu-block] [Qemu-devel] [PATCH v2 1/2] block/accounting: introduce latency histogram Date: Thu, 8 Mar 2018 21:14:34 +0300 User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0

```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.

---
```
```
```
```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.
```

1. interval_boundaries
2. bin_boundaries
3. boundaries

(and same names with s/_/-/ for qapi)

--
Best regards,