+2019-05-10 Wilco Dijkstra <wdijkstr@arm.com>
+
+ [BZ #24531]
+ * malloc/malloc.c (MAX_TCACHE_COUNT): New define.
+ (do_set_tcache_count): Only update if count is small enough.
+ * manual/tunables.texi (glibc.malloc.tcache_count): Document max value.
+
2019-05-10 Florian Weimer <fweimer@redhat.com>
* nptl/sem_close.c (struct walk_closure): Define.
tcache_entry *entries[TCACHE_MAX_BINS];
} tcache_perthread_struct;
+#define MAX_TCACHE_COUNT 127 /* Maximum value of counts[] entries. */
+
static __thread bool tcache_shutting_down = false;
static __thread tcache_perthread_struct *tcache = NULL;
static __always_inline int
do_set_tcache_count (size_t value)
{
- LIBC_PROBE (memory_tunable_tcache_count, 2, value, mp_.tcache_count);
- mp_.tcache_count = value;
+ if (value <= MAX_TCACHE_COUNT)
+ {
+ LIBC_PROBE (memory_tunable_tcache_count, 2, value, mp_.tcache_count);
+ mp_.tcache_count = value;
+ }
return 1;
}
@deftp Tunable glibc.malloc.tcache_count
The maximum number of chunks of each size to cache. The default is 7.
-There is no upper limit, other than available system memory. If set
-to zero, the per-thread cache is effectively disabled.
+The upper limit is 127. If set to zero, the per-thread cache is effectively
+disabled.
The approximate maximum overhead of the per-thread cache is thus equal
to the number of bins times the chunk count in each bin times the size