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authorWilco Dijkstra <wdijkstr@arm.com>2019-05-17 18:16:20 +0100
committerWilco Dijkstra <wdijkstr@arm.com>2019-05-17 18:16:20 +0100
commit1f50f2ad854c84ead522bfc7331b46dbe6057d53 (patch)
treea350b22461a9b819877711cf88a53f0191b388b5 /malloc
parentfef7c63cd5a5a3150dc9465687359351afab5010 (diff)
downloadglibc-1f50f2ad854c84ead522bfc7331b46dbe6057d53.tar.gz
Small tcache improvements
Change the tcache->counts[] entries to uint16_t - this removes the limit set by char and allows a larger tcache. Remove a few redundant asserts. bench-malloc-thread with 4 threads is ~15% faster on Cortex-A72. Reviewed-by: DJ Delorie <dj@redhat.com> * malloc/malloc.c (MAX_TCACHE_COUNT): Increase to UINT16_MAX. (tcache_put): Remove redundant assert. (tcache_get): Remove redundant asserts. (__libc_malloc): Check tcache count is not zero. * manual/tunables.texi (glibc.malloc.tcache_count): Update maximum.
Diffstat (limited to 'malloc')
-rw-r--r--malloc/malloc.c14
1 files changed, 6 insertions, 8 deletions
diff --git a/malloc/malloc.c b/malloc/malloc.c
index b8baaa2706..00ce48cf58 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -321,6 +321,10 @@ __malloc_assert (const char *assertion, const char *file, unsigned int line,
/* This is another arbitrary limit, which tunables can change. Each
tcache bin will hold at most this number of chunks. */
# define TCACHE_FILL_COUNT 7
+
+/* Maximum chunks in tcache bins for tunables. This value must fit the range
+ of tcache->counts[] entries, else they may overflow. */
+# define MAX_TCACHE_COUNT UINT16_MAX
#endif
@@ -2901,12 +2905,10 @@ typedef struct tcache_entry
time), this is for performance reasons. */
typedef struct tcache_perthread_struct
{
- char counts[TCACHE_MAX_BINS];
+ uint16_t counts[TCACHE_MAX_BINS];
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;
@@ -2916,7 +2918,6 @@ static __always_inline void
tcache_put (mchunkptr chunk, size_t tc_idx)
{
tcache_entry *e = (tcache_entry *) chunk2mem (chunk);
- assert (tc_idx < TCACHE_MAX_BINS);
/* Mark this chunk as "in the tcache" so the test in _int_free will
detect a double free. */
@@ -2933,8 +2934,6 @@ static __always_inline void *
tcache_get (size_t tc_idx)
{
tcache_entry *e = tcache->entries[tc_idx];
- assert (tc_idx < TCACHE_MAX_BINS);
- assert (tcache->counts[tc_idx] > 0);
tcache->entries[tc_idx] = e->next;
--(tcache->counts[tc_idx]);
e->key = NULL;
@@ -3046,9 +3045,8 @@ __libc_malloc (size_t bytes)
DIAG_PUSH_NEEDS_COMMENT;
if (tc_idx < mp_.tcache_bins
- /*&& tc_idx < TCACHE_MAX_BINS*/ /* to appease gcc */
&& tcache
- && tcache->entries[tc_idx] != NULL)
+ && tcache->counts[tc_idx] > 0)
{
return tcache_get (tc_idx);
}