[all-commits] [llvm/llvm-project] 97795b: tsan: optimize test-only barrier

[Dmitry Vyukov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 97795be22f634667ce7a022398c59ccc9f7440eb
      https://github.com/llvm/llvm-project/commit/97795be22f634667ce7a022398c59ccc9f7440eb
  Author: Dmitry Vyukov <dvyukov at google.com>
  Date:   2021-07-30 (Fri, 30 Jul 2021)

  Changed paths:
    M compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp
    M compiler-rt/test/tsan/test.h

  Log Message:
  -----------
  tsan: optimize test-only barrier

The updated lots_of_threads.c test with 300 threads
started running for too long on machines with low
hardware parallelism (e.g. taskset -c 0-1).
On lots of CPUs it finishes in ~2 secs. But with
taskset -c 0-1 it runs for hundreds of seconds
effectively spinning in the barrier in the sleep loop.

We now have the handy futex API in sanitizer_common.
Use it instead of the passive spin loop.
It makes the test run only faster with taskset -c 0-1,
it runs for ~1.5 secs, while with full parallelism
it still runs for ~2 secs (but consumes less CPU time).

Depends on D107131.

Reviewed By: vitalybuka

Differential Revision: https://reviews.llvm.org/D107132