Stream: git-wasmtime

Topic: wasmtime / issue #6151 Profiling with Perf

Wasmtime GitHub notifications bot (Apr 05 2023 at 15:47):

MrSarius opened issue #6151:

I am currently following the wasmtime perf example from the documentation.

The following seem to work for me:

$ rustc --target wasm32-wasi fib.rs -O
$ perf record -k mono wasmtime fib.wasm -- --profile=jitdump
fib(42) = 267914296
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.140 MB perf.data (3618 samples) ]
$ perf inject --jit --input perf.data --output perf.jit.data

But the output of perf report --input perf.jit.data shows unresolved symbols (and just 11.19% for the top function call):

Samples: 3K of event 'cpu-clock:uhpppH', Event count (approx.): 904500000
Overhead  Command   Shared Object     Symbol
  11.19%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db37646b
   7.30%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db3764d0
   6.41%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db376483
   6.14%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db376460
   4.86%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db3764b0
   4.12%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db376476
   3.81%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db3764a8
   3.65%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db3764a5
   3.65%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db3764da
   3.59%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db376461
...

Any idea why? I'm following the instructions step by step.

the only thing I had to change from the documentation was
$ perf record -k mono wasmtime --profile=jitdump fib.wasm
to
$ perf record -k mono wasmtime fib.wasm -- --profile=jitdump.
The documentation seems to be outdated here?

Wasmtime GitHub notifications bot (Apr 05 2023 at 16:18):

jameysharp commented on issue #6151:

What does wasmtime --version say?

I think your issue may actually be that the documentation is too new: it reflects changes which are in the upcoming 8.0.0 release. On earlier versions, I believe the flag you needed was --jitdump.

I think the only reason that adding the --profile flag after -- eliminated error messages was because it made Wasmtime ignore the flag and try to pass it to your wasm program instead.

Wasmtime GitHub notifications bot (Apr 05 2023 at 16:39):

MrSarius commented on issue #6151:

$ wasmtime --version
wasmtime-cli 7.0.0

Thank you, that was the issue!

Wasmtime GitHub notifications bot (Apr 05 2023 at 16:55):

jameysharp commented on issue #6151:

Great, I'm glad I could help!

Wasmtime GitHub notifications bot (Apr 05 2023 at 16:55):

jameysharp closed issue #6151:

I am currently following the wasmtime perf example from the documentation.

The following seem to work for me:

$ rustc --target wasm32-wasi fib.rs -O
$ perf record -k mono wasmtime fib.wasm -- --profile=jitdump
fib(42) = 267914296
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.140 MB perf.data (3618 samples) ]
$ perf inject --jit --input perf.data --output perf.jit.data

But the output of perf report --input perf.jit.data shows unresolved symbols (and just 11.19% for the top function call):

Samples: 3K of event 'cpu-clock:uhpppH', Event count (approx.): 904500000
Overhead  Command   Shared Object     Symbol
  11.19%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db37646b
   7.30%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db3764d0
   6.41%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db376483
   6.14%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db376460
   4.86%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db3764b0
   4.12%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db376476
   3.81%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db3764a8
   3.65%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db3764a5
   3.65%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db3764da
   3.59%  wasmtime  [JIT] tid 12785   [.] 0x00007f18db376461
...

Any idea why? I'm following the instructions step by step.

the only thing I had to change from the documentation was
$ perf record -k mono wasmtime --profile=jitdump fib.wasm
to
$ perf record -k mono wasmtime fib.wasm -- --profile=jitdump.
The documentation seems to be outdated here?

Last updated: Dec 23 2024 at 12:05 UTC