Cannot profile local rustc

[Nicholas-Baron]

I am trying to address the rustc regression shown here.
I have checked out the latest version of this repo and cannot use profile_local.
Build steps:

• rustc with ./x.py b --stage 2 library/test
• rustc-perf with cargo build (same result with --release)

The following command will fail:

./target/release/collector profile_local cachegrind ../rust/build/x86_64-unknown-linux-gnu/stage2/bin/rustc mine --include diesel

with this output:

Profiling with Cachegrind
1 benchmark remaining
Preparing diesel
Running diesel: Check + [Full, IncrFull, IncrUnchanged, IncrPatched]
collector error: Failed to profile 'diesel' with Cachegrind, recorded: failed to obtain pkgid in '"/tmp/.tmpZsNXtr"'

Caused by:
    No such file or directory (os error 2)
collector error: 1 benchmarks failed

[Mark-Simulacrum]

I wasn't able to reproduce this change after building same as you did - I wonder if you can check that valgrind --tool=cachegrind echo works for you... but it also looks like there's some error with a pkgid not resolving, not sure why that would be.

[Nicholas-Baron]

valgrind --tool=cachegrind echo "Hello World" gives the following output:

==2865== Cachegrind, a cache and branch-prediction profiler
==2865== Copyright (C) 2002-2017, and GNU GPL'd, by Nicholas Nethercote et al.
==2865== Using Valgrind-3.16.1 and LibVEX; rerun with -h for copyright info
==2865== Command: echo Hello\ world
==2865==
--2865-- warning: L3 cache found, using its data for the LL simulation.
Hello world
==2865==
==2865== I   refs:      180,780
==2865== I1  misses:      1,201
==2865== LLi misses:      1,182
==2865== I1  miss rate:    0.66%
==2865== LLi miss rate:    0.65%
==2865==
==2865== D   refs:       62,641  (44,565 rd   + 18,076 wr)
==2865== D1  misses:      2,314  ( 1,701 rd   +    613 wr)
==2865== LLd misses:      1,958  ( 1,379 rd   +    579 wr)
==2865== D1  miss rate:     3.7% (   3.8%     +    3.4%  )
==2865== LLd miss rate:     3.1% (   3.1%     +    3.2%  )
==2865==
==2865== LL refs:         3,515  ( 2,902 rd   +    613 wr)
==2865== LL misses:       3,140  ( 2,561 rd   +    579 wr)
==2865== LL miss rate:      1.3% (   1.1%     +    3.2%  )

So I assume valgrind works.

[tgnottingham]

@Nicholas-Baron Does this error still occur for you? Can you reproduce it with RUST_LOG=trace? Based on the output and inspection of the code, it kind of looks like the path to cargo that it's using internally points to some non-existent file. The logs should give us more of a clue.

[Nicholas-Baron]

@tgnottingham It seems to be work now. The profile is taking a long time, but that is expected with valgrind.
When it finishes, I will close this issue, as it seems to have been resolved.

[Nicholas-Baron]

Looks like it did work. Now time to interpret the results folder.