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proc_maps: Parse address and device without allocating #572

Merged
merged 2 commits into from
Sep 22, 2023
Merged

proc_maps: Parse address and device without allocating #572

merged 2 commits into from
Sep 22, 2023

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javierhonduco
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@javierhonduco javierhonduco commented Sep 19, 2023

In our project we need to parse proc maps pretty frequently and we've noticed that there are lots of small allocations coming from parsing the device and addresses from procfs' maps file.

The rough split of memory allocated is:

  • bufio.(*Scanner).Text: 25%
  • strings.Split: 50%
  • string.Fields: 25%

The two callers of strings.Split are the two parsing functions that we are optimising here. I've added some benchmarks to show the improvements.

image

Before

$ go test -benchmem -run=^$ -bench ^BenchmarkParse.*$ github.com/prometheus/procfs
goos: linux
goarch: amd64
pkg: github.com/prometheus/procfs
cpu: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
BenchmarkParseAddress-12        12218004               123.0 ns/op            32 B/op          1 allocs/op
BenchmarkParseDevice-12         15074881                85.11 ns/op           32 B/op          1 allocs/op
PASS
ok      github.com/prometheus/procfs    2.978s

After

$ go test -benchmem -run=^$ -bench ^BenchmarkParse.*$ github.com/prometheus/procfs
goos: linux
goarch: amd64
pkg: github.com/prometheus/procfs
cpu: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
BenchmarkParseAddress-12        28619314                50.45 ns/op            0 B/op          0 allocs/op
BenchmarkParseDevice-12         49721935                29.66 ns/op            0 B/op          0 allocs/op
PASS
ok      github.com/prometheus/procfs    2.991s

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@kakkoyun kakkoyun left a comment

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LGTM 🥇

javierhonduco and others added 2 commits September 19, 2023 13:22
In our project we need to parse proc maps pretty frequently and we've
noticed that there are lots of small allocations coming from parsing the
device and addresses from procfs' maps file.

The rough split of memory allocated is:
- bufio.(*Scanner).Text: 25%
- strings.Split: 50%
- string.Fields: 25%

The two callers of strings.Split are the two parsing functions that we
are optimising here. I've added some benchmarks to show the
improvements.

Before
======

```
$ go test -benchmem -run=^$ -bench ^BenchmarkParse.*$ github.com/prometheus/procfs
goos: linux
goarch: amd64
pkg: github.com/prometheus/procfs
cpu: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
BenchmarkParseAddress-12        12218004               123.0 ns/op            32 B/op          1 allocs/op
BenchmarkParseDevice-12         15074881                85.11 ns/op           32 B/op          1 allocs/op
PASS
ok      github.com/prometheus/procfs    2.978s
```

After
=====

```
$ go test -benchmem -run=^$ -bench ^BenchmarkParse.*$ github.com/prometheus/procfs
goos: linux
goarch: amd64
pkg: github.com/prometheus/procfs
cpu: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
BenchmarkParseAddress-12        28619314                50.45 ns/op            0 B/op          0 allocs/op
BenchmarkParseDevice-12         49721935                29.66 ns/op            0 B/op          0 allocs/op
PASS
ok      github.com/prometheus/procfs    2.991s
```

Signed-off-by: Francisco Javier Honduvilla Coto <[email protected]>
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@SuperQ SuperQ left a comment

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Very nice.

@SuperQ SuperQ merged commit a5ae62f into prometheus:master Sep 22, 2023
2 checks passed
@javierhonduco javierhonduco deleted the optimise-maps-device-and-address-parsing branch September 22, 2023 14:15
jritter pushed a commit to jritter/procfs that referenced this pull request Jul 15, 2024
In our project we need to parse proc maps pretty frequently and we've
noticed that there are lots of small allocations coming from parsing the
device and addresses from procfs' maps file.

The rough split of memory allocated is:
- bufio.(*Scanner).Text: 25%
- strings.Split: 50%
- string.Fields: 25%

The two callers of strings.Split are the two parsing functions that we
are optimising here. I've added some benchmarks to show the
improvements.

Before
======

```
$ go test -benchmem -run=^$ -bench ^BenchmarkParse.*$ github.com/prometheus/procfs
goos: linux
goarch: amd64
pkg: github.com/prometheus/procfs
cpu: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
BenchmarkParseAddress-12        12218004               123.0 ns/op            32 B/op          1 allocs/op
BenchmarkParseDevice-12         15074881                85.11 ns/op           32 B/op          1 allocs/op
PASS
ok      github.com/prometheus/procfs    2.978s
```

After
=====

```
$ go test -benchmem -run=^$ -bench ^BenchmarkParse.*$ github.com/prometheus/procfs
goos: linux
goarch: amd64
pkg: github.com/prometheus/procfs
cpu: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
BenchmarkParseAddress-12        28619314                50.45 ns/op            0 B/op          0 allocs/op
BenchmarkParseDevice-12         49721935                29.66 ns/op            0 B/op          0 allocs/op
PASS
ok      github.com/prometheus/procfs    2.991s
```

Signed-off-by: Francisco Javier Honduvilla Coto <[email protected]>
Co-authored-by: Ben Kochie <[email protected]>
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3 participants