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Ptrace vfork#1128

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sporksmith merged 2 commits intoshadow:devfrom
sporksmith:ptrace-vfork
Mar 2, 2021
Merged

Ptrace vfork#1128
sporksmith merged 2 commits intoshadow:devfrom
sporksmith:ptrace-vfork

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@sporksmith sporksmith commented Feb 27, 2021

Use vfork in thread_ptrace

@sporksmith sporksmith force-pushed the ptrace-vfork branch 3 times, most recently from 101eca4 to 527817c Compare February 27, 2021 18:26
@sporksmith sporksmith marked this pull request as ready for review February 27, 2021 18:26
@sporksmith sporksmith mentioned this pull request Feb 27, 2021
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sporksmith commented Mar 1, 2021

Hmm, I was expecting the timeouts in the coverage build to go away once #1131 was merged, but they didn't.

Looking more closely, there are a lot of lines like:

profiling: /__w/shadow/shadow/build/src/main/CMakeFiles/shadow.dir/main.c.gcda: cannot merge previous run count: corrupt object tag (0x01000000)

I suspect that the profiling code ends up corrupting its in-memory data structures due to the code in between the vfork and the exec. I'll arrange to use fork in coverage builds.

@robgjansen robgjansen added the Component: Main Composing the core Shadow executable label Mar 1, 2021
@sporksmith
Use vfork in thread_ptrace
4e46365 
This is a substantial performance savings in experiments with many
hosts.

This is an item in shadow#1041
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codecov bot commented Mar 2, 2021

Codecov Report

Merging #1128 (58a7d25) into dev (b72c1cf) will decrease coverage by 0.10%.
The diff coverage is 100.00%.

Impacted file tree graph

@@            Coverage Diff             @@
##              dev    #1128      +/-   ##
==========================================
- Coverage   57.06%   56.96%   -0.11%     
==========================================
  Files         136      136              
  Lines       20133    20130       -3     
  Branches     4842     4841       -1     
==========================================
- Hits        11489    11467      -22     
- Misses       5670     5687      +17     
- Partials     2974     2976       +2
Flag Coverage Δ
tests 56.96% <100.00%> (-0.11%) ⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files Coverage Δ
src/main/host/thread_ptrace.c 63.21% <100.00%> (-2.05%) ⬇️
src/main/host/syscall/process.c 23.68% <0.00%> (-7.90%) ⬇️
src/main/host/process.c 71.62% <0.00%> (-0.55%) ⬇️
src/main/host/syscall_handler.c 54.78% <0.00%> (-0.44%) ⬇️
src/support/logger/rust_bindings/src/lib.rs 40.26% <0.00%> (-0.15%) ⬇️
src/main/host/descriptor/file.c 31.13% <0.00%> (+0.22%) ⬆️

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@sporksmith sporksmith merged commit cd42474 into shadow:dev Mar 2, 2021
@sporksmith sporksmith deleted the ptrace-vfork branch March 2, 2021 02:42
@robgjansen robgjansen added the Tag: Performance Related to improving shadow's run-time label Mar 3, 2021
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Component: Main Composing the core Shadow executable Tag: Performance Related to improving shadow's run-time

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Minimum viable prototype of process-b...

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