65 lines
2.1 KiB
Diff
65 lines
2.1 KiB
Diff
commit ee0bc695303775da5026091a65e8ec2b764f4a26
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Author: Bruno Haible <bruno@clisp.org>
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Date: Mon Nov 11 15:40:52 2024 +0100
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nproc: Use affinity mask even in out-of-memory situations.
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* lib/nproc.c (num_processors_via_affinity_mask): Use a stack-allocated
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cpu_set_t as fallback. Add comments.
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diff --git a/lib/nproc.c b/lib/nproc.c
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index 48bc3d06fa..0b5898d88f 100644
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--- a/lib/nproc.c
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+++ b/lib/nproc.c
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@@ -125,15 +125,25 @@ num_processors_via_affinity_mask (void)
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return count;
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}
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}
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-#elif HAVE_SCHED_GETAFFINITY_LIKE_GLIBC \
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- && defined CPU_ALLOC_SIZE /* glibc >= 2.6 */
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+#elif HAVE_SCHED_GETAFFINITY_LIKE_GLIBC /* glibc >= 2.3.4 */
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+ /* There are two ways to use the sched_getaffinity() function:
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+ - With a statically-sized cpu_set_t.
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+ - With a dynamically-sized cpu_set_t.
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+ Documentation:
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+ <https://www.kernel.org/doc/man-pages/online/pages/man2/sched_getaffinity.2.html>
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+ <https://www.kernel.org/doc/man-pages/online/pages/man3/CPU_SET.3.html>
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+ The second way has the advantage that it works on systems with more than
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+ 1024 CPUs. The first way has the advantage that it works also when memory
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+ is tight. */
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+# if defined CPU_ALLOC_SIZE /* glibc >= 2.6 */
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{
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unsigned int alloc_count = 1024;
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- while (1)
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+ for (;;)
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{
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cpu_set_t *set = CPU_ALLOC (alloc_count);
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if (set == NULL)
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- return 0;
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+ /* Out of memory. */
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+ break;
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unsigned int size = CPU_ALLOC_SIZE (alloc_count);
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if (sched_getaffinity (0, size, set) == 0)
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{
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@@ -143,16 +153,19 @@ num_processors_via_affinity_mask (void)
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}
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if (errno != EINVAL)
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{
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+ /* Some other error. */
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CPU_FREE (set);
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return 0;
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}
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CPU_FREE (set);
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+ /* Retry with some larger cpu_set_t. */
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alloc_count *= 2;
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if (alloc_count == 0)
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+ /* Integer overflow. Avoid an endless loop. */
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return 0;
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}
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}
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-#elif HAVE_SCHED_GETAFFINITY_LIKE_GLIBC /* glibc >= 2.3.4 */
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+# endif
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{
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cpu_set_t set;
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