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beorn7 c0879d64cf promql: Separate `Point` into `FPoint` and `HPoint` In other words: Instead of having a “polymorphous” `Point` that can either contain a float value or a histogram value, use an `FPoint` for floats and an `HPoint` for histograms. This seemingly small change has a _lot_ of repercussions throughout the codebase. The idea here is to avoid the increase in size of `Point` arrays that happened after native histograms had been added. The higher-level data structures (`Sample`, `Series`, etc.) are still “polymorphous”. The same idea could be applied to them, but at each step the trade-offs needed to be evaluated. The idea with this change is to do the minimum necessary to get back to pre-histogram performance for functions that do not touch histograms. Here are comparisons for the `changes` function. The test data doesn't include histograms yet. Ideally, there would be no change in the benchmark result at all. First runtime v2.39 compared to directly prior to this commit: ``` name old time/op new time/op delta RangeQuery/expr=changes(a_one[1d]),steps=1-16 391µs ± 2% 542µs ± 1% +38.58% (p=0.000 n=9+8) RangeQuery/expr=changes(a_one[1d]),steps=10-16 452µs ± 2% 617µs ± 2% +36.48% (p=0.000 n=10+10) RangeQuery/expr=changes(a_one[1d]),steps=100-16 1.12ms ± 1% 1.36ms ± 2% +21.58% (p=0.000 n=8+10) RangeQuery/expr=changes(a_one[1d]),steps=1000-16 7.83ms ± 1% 8.94ms ± 1% +14.21% (p=0.000 n=10+10) RangeQuery/expr=changes(a_ten[1d]),steps=1-16 2.98ms ± 0% 3.30ms ± 1% +10.67% (p=0.000 n=9+10) RangeQuery/expr=changes(a_ten[1d]),steps=10-16 3.66ms ± 1% 4.10ms ± 1% +11.82% (p=0.000 n=10+10) RangeQuery/expr=changes(a_ten[1d]),steps=100-16 10.5ms ± 0% 11.8ms ± 1% +12.50% (p=0.000 n=8+10) RangeQuery/expr=changes(a_ten[1d]),steps=1000-16 77.6ms ± 1% 87.4ms ± 1% +12.63% (p=0.000 n=9+9) RangeQuery/expr=changes(a_hundred[1d]),steps=1-16 30.4ms ± 2% 32.8ms ± 1% +8.01% (p=0.000 n=10+10) RangeQuery/expr=changes(a_hundred[1d]),steps=10-16 37.1ms ± 2% 40.6ms ± 2% +9.64% (p=0.000 n=10+10) RangeQuery/expr=changes(a_hundred[1d]),steps=100-16 105ms ± 1% 117ms ± 1% +11.69% (p=0.000 n=10+10) RangeQuery/expr=changes(a_hundred[1d]),steps=1000-16 783ms ± 3% 876ms ± 1% +11.83% (p=0.000 n=9+10) ``` And then runtime v2.39 compared to after this commit: ``` name old time/op new time/op delta RangeQuery/expr=changes(a_one[1d]),steps=1-16 391µs ± 2% 547µs ± 1% +39.84% (p=0.000 n=9+8) RangeQuery/expr=changes(a_one[1d]),steps=10-16 452µs ± 2% 616µs ± 2% +36.15% (p=0.000 n=10+10) RangeQuery/expr=changes(a_one[1d]),steps=100-16 1.12ms ± 1% 1.26ms ± 1% +12.20% (p=0.000 n=8+10) RangeQuery/expr=changes(a_one[1d]),steps=1000-16 7.83ms ± 1% 7.95ms ± 1% +1.59% (p=0.000 n=10+8) RangeQuery/expr=changes(a_ten[1d]),steps=1-16 2.98ms ± 0% 3.38ms ± 2% +13.49% (p=0.000 n=9+10) RangeQuery/expr=changes(a_ten[1d]),steps=10-16 3.66ms ± 1% 4.02ms ± 1% +9.80% (p=0.000 n=10+9) RangeQuery/expr=changes(a_ten[1d]),steps=100-16 10.5ms ± 0% 10.8ms ± 1% +3.08% (p=0.000 n=8+10) RangeQuery/expr=changes(a_ten[1d]),steps=1000-16 77.6ms ± 1% 78.1ms ± 1% +0.58% (p=0.035 n=9+10) RangeQuery/expr=changes(a_hundred[1d]),steps=1-16 30.4ms ± 2% 33.5ms ± 4% +10.18% (p=0.000 n=10+10) RangeQuery/expr=changes(a_hundred[1d]),steps=10-16 37.1ms ± 2% 40.0ms ± 1% +7.98% (p=0.000 n=10+10) RangeQuery/expr=changes(a_hundred[1d]),steps=100-16 105ms ± 1% 107ms ± 1% +1.92% (p=0.000 n=10+10) RangeQuery/expr=changes(a_hundred[1d]),steps=1000-16 783ms ± 3% 775ms ± 1% -1.02% (p=0.019 n=9+9) ``` In summary, the runtime doesn't really improve with this change for queries with just a few steps. For queries with many steps, this commit essentially reinstates the old performance. This is good because the many-step queries are the one that matter most (longest absolute runtime). In terms of allocations, though, this commit doesn't make a dent at all (numbers not shown). The reason is that most of the allocations happen in the sampleRingIterator (in the storage package), which has to be addressed in a separate commit. Signed-off-by: beorn7 <beorn@grafana.com>	2 years ago
..
prometheus	Use a random port in cmd/prometheus tests	2 years ago
promtool	promql: Separate `Point` into `FPoint` and `HPoint`	2 years ago

beorn7 c0879d64cf promql: Separate `Point` into `FPoint` and `HPoint`

In other words: Instead of having a “polymorphous” `Point` that can
either contain a float value or a histogram value, use an `FPoint` for
floats and an `HPoint` for histograms.

This seemingly small change has a _lot_ of repercussions throughout
the codebase.

The idea here is to avoid the increase in size of `Point` arrays that
happened after native histograms had been added.

The higher-level data structures (`Sample`, `Series`, etc.) are still
“polymorphous”. The same idea could be applied to them, but at each
step the trade-offs needed to be evaluated.

The idea with this change is to do the minimum necessary to get back
to pre-histogram performance for functions that do not touch
histograms. Here are comparisons for the `changes` function. The test
data doesn't include histograms yet. Ideally, there would be no change
in the benchmark result at all.

First runtime v2.39 compared to directly prior to this commit:

```
name                                                  old time/op    new time/op    delta
RangeQuery/expr=changes(a_one[1d]),steps=1-16            391µs ± 2%     542µs ± 1%  +38.58%  (p=0.000 n=9+8)
RangeQuery/expr=changes(a_one[1d]),steps=10-16           452µs ± 2%     617µs ± 2%  +36.48%  (p=0.000 n=10+10)
RangeQuery/expr=changes(a_one[1d]),steps=100-16         1.12ms ± 1%    1.36ms ± 2%  +21.58%  (p=0.000 n=8+10)
RangeQuery/expr=changes(a_one[1d]),steps=1000-16        7.83ms ± 1%    8.94ms ± 1%  +14.21%  (p=0.000 n=10+10)
RangeQuery/expr=changes(a_ten[1d]),steps=1-16           2.98ms ± 0%    3.30ms ± 1%  +10.67%  (p=0.000 n=9+10)
RangeQuery/expr=changes(a_ten[1d]),steps=10-16          3.66ms ± 1%    4.10ms ± 1%  +11.82%  (p=0.000 n=10+10)
RangeQuery/expr=changes(a_ten[1d]),steps=100-16         10.5ms ± 0%    11.8ms ± 1%  +12.50%  (p=0.000 n=8+10)
RangeQuery/expr=changes(a_ten[1d]),steps=1000-16        77.6ms ± 1%    87.4ms ± 1%  +12.63%  (p=0.000 n=9+9)
RangeQuery/expr=changes(a_hundred[1d]),steps=1-16       30.4ms ± 2%    32.8ms ± 1%   +8.01%  (p=0.000 n=10+10)
RangeQuery/expr=changes(a_hundred[1d]),steps=10-16      37.1ms ± 2%    40.6ms ± 2%   +9.64%  (p=0.000 n=10+10)
RangeQuery/expr=changes(a_hundred[1d]),steps=100-16      105ms ± 1%     117ms ± 1%  +11.69%  (p=0.000 n=10+10)
RangeQuery/expr=changes(a_hundred[1d]),steps=1000-16     783ms ± 3%     876ms ± 1%  +11.83%  (p=0.000 n=9+10)
```

And then runtime v2.39 compared to after this commit:

```
name                                                  old time/op    new time/op    delta
RangeQuery/expr=changes(a_one[1d]),steps=1-16            391µs ± 2%     547µs ± 1%  +39.84%  (p=0.000 n=9+8)
RangeQuery/expr=changes(a_one[1d]),steps=10-16           452µs ± 2%     616µs ± 2%  +36.15%  (p=0.000 n=10+10)
RangeQuery/expr=changes(a_one[1d]),steps=100-16         1.12ms ± 1%    1.26ms ± 1%  +12.20%  (p=0.000 n=8+10)
RangeQuery/expr=changes(a_one[1d]),steps=1000-16        7.83ms ± 1%    7.95ms ± 1%   +1.59%  (p=0.000 n=10+8)
RangeQuery/expr=changes(a_ten[1d]),steps=1-16           2.98ms ± 0%    3.38ms ± 2%  +13.49%  (p=0.000 n=9+10)
RangeQuery/expr=changes(a_ten[1d]),steps=10-16          3.66ms ± 1%    4.02ms ± 1%   +9.80%  (p=0.000 n=10+9)
RangeQuery/expr=changes(a_ten[1d]),steps=100-16         10.5ms ± 0%    10.8ms ± 1%   +3.08%  (p=0.000 n=8+10)
RangeQuery/expr=changes(a_ten[1d]),steps=1000-16        77.6ms ± 1%    78.1ms ± 1%   +0.58%  (p=0.035 n=9+10)
RangeQuery/expr=changes(a_hundred[1d]),steps=1-16       30.4ms ± 2%    33.5ms ± 4%  +10.18%  (p=0.000 n=10+10)
RangeQuery/expr=changes(a_hundred[1d]),steps=10-16      37.1ms ± 2%    40.0ms ± 1%   +7.98%  (p=0.000 n=10+10)
RangeQuery/expr=changes(a_hundred[1d]),steps=100-16      105ms ± 1%     107ms ± 1%   +1.92%  (p=0.000 n=10+10)
RangeQuery/expr=changes(a_hundred[1d]),steps=1000-16     783ms ± 3%     775ms ± 1%   -1.02%  (p=0.019 n=9+9)
```

In summary, the runtime doesn't really improve with this change for
queries with just a few steps. For queries with many steps, this
commit essentially reinstates the old performance. This is good
because the many-step queries are the one that matter most (longest
absolute runtime).

In terms of allocations, though, this commit doesn't make a dent at
all (numbers not shown). The reason is that most of the allocations
happen in the sampleRingIterator (in the storage package), which has
to be addressed in a separate commit.

Signed-off-by: beorn7 <beorn@grafana.com>

2 years ago

prometheus

Use a random port in cmd/prometheus tests

2 years ago

promtool

promql: Separate `Point` into `FPoint` and `HPoint`

2 years ago