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* [binutils-gdb] [gdbsupport] Add parallel_for_each_debug
@ 2022-07-18 3:34 Tom de Vries
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From: Tom de Vries @ 2022-07-18 3:34 UTC (permalink / raw)
To: gdb-cvs
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=53944a3bf51cdff9ad30a0c3740b8124213fdab9
commit 53944a3bf51cdff9ad30a0c3740b8124213fdab9
Author: Tom de Vries <tdevries@suse.de>
Date: Mon Jul 18 05:34:01 2022 +0200
[gdbsupport] Add parallel_for_each_debug
Add a parallel_for_each_debug variable, set to false by default.
With an a.out compiled from hello world, we get with
parallel_for_each_debug == true:
...
$ gdb -q -batch a.out -ex start
...
Parallel for: n_elements: 7271
Parallel for: minimum elements per thread: 10
Parallel for: elts_per_thread: 1817
Parallel for: elements on worker thread 0 : 1817
Parallel for: elements on worker thread 1 : 1817
Parallel for: elements on worker thread 2 : 1817
Parallel for: elements on worker thread 3 : 0
Parallel for: elements on main thread : 1820
Temporary breakpoint 1, main () at /home/vries/hello.c:6
6 printf ("hello\n");
...
Tested on x86_64-linux.
Diff:
---
gdbsupport/parallel-for.h | 24 +++++++++++++++++++++++-
1 file changed, 23 insertions(+), 1 deletion(-)
diff --git a/gdbsupport/parallel-for.h b/gdbsupport/parallel-for.h
index a614fc35766..cfe8a6e4f09 100644
--- a/gdbsupport/parallel-for.h
+++ b/gdbsupport/parallel-for.h
@@ -139,7 +139,12 @@ parallel_for_each (unsigned n, RandomIt first, RandomIt last,
using result_type
= typename std::result_of<RangeFunction (RandomIt, RandomIt)>::type;
- size_t n_threads = thread_pool::g_thread_pool->thread_count ();
+ /* If enabled, print debug info about how the work is distributed across
+ the threads. */
+ const int parallel_for_each_debug = false;
+
+ size_t n_worker_threads = thread_pool::g_thread_pool->thread_count ();
+ size_t n_threads = n_worker_threads;
size_t n_elements = last - first;
size_t elts_per_thread = 0;
if (n_threads > 1)
@@ -155,9 +160,19 @@ parallel_for_each (unsigned n, RandomIt first, RandomIt last,
size_t count = n_threads == 0 ? 0 : n_threads - 1;
gdb::detail::par_for_accumulator<result_type> results (count);
+ if (parallel_for_each_debug)
+ {
+ debug_printf (_("Parallel for: n_elements: %zu\n"), n_elements);
+ debug_printf (_("Parallel for: minimum elements per thread: %u\n"), n);
+ debug_printf (_("Parallel for: elts_per_thread: %zu\n"), elts_per_thread);
+ }
+
for (int i = 0; i < count; ++i)
{
RandomIt end = first + elts_per_thread;
+ if (parallel_for_each_debug)
+ debug_printf (_("Parallel for: elements on worker thread %i\t: %zu\n"),
+ i, (size_t)(end - first));
results.post (i, [=] ()
{
return callback (first, end);
@@ -165,7 +180,14 @@ parallel_for_each (unsigned n, RandomIt first, RandomIt last,
first = end;
}
+ for (int i = count; i < n_worker_threads; ++i)
+ if (parallel_for_each_debug)
+ debug_printf (_("Parallel for: elements on worker thread %i\t: 0\n"), i);
+
/* Process all the remaining elements in the main thread. */
+ if (parallel_for_each_debug)
+ debug_printf (_("Parallel for: elements on main thread\t\t: %zu\n"),
+ (size_t)(last - first));
return results.finish ([=] ()
{
return callback (first, last);
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