diff options
| author | Wilco Dijkstra <wdijkstr@arm.com> | 2019-05-17 18:16:20 +0100 |
|---|---|---|
| committer | Arjun Shankar <ashankar@redhat.com> | 2019-10-30 12:01:42 +0100 |
| commit | f88c59f4657ac2e0bab8f51f60022ecbe7f12e2e (patch) | |
| tree | 72d11950c9a3d2fa02f0db6f666265f120115c79 | |
| parent | 3640758943c856268bc12a3307838c2a65d2f9ea (diff) | |
| download | glibc-f88c59f4657ac2e0bab8f51f60022ecbe7f12e2e.tar.gz glibc-f88c59f4657ac2e0bab8f51f60022ecbe7f12e2e.tar.xz glibc-f88c59f4657ac2e0bab8f51f60022ecbe7f12e2e.zip | |
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. (cherry picked from commit 1f50f2ad854c84ead522bfc7331b46dbe6057d53)
| -rw-r--r-- | ChangeLog | 8 | ||||
| -rw-r--r-- | malloc/malloc.c | 14 | ||||
| -rw-r--r-- | manual/tunables.texi | 2 |
3 files changed, 15 insertions, 9 deletions
diff --git a/ChangeLog b/ChangeLog index 668ae78ae7..8c5c162f56 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,11 @@ +2019-05-17 Wilco Dijkstra <wdijkstr@arm.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. + 2019-02-04 Joseph Myers <joseph@codesourcery.com> * malloc/malloc.c (tcache_get): Compare tcache->counts[tc_idx] diff --git a/malloc/malloc.c b/malloc/malloc.c index 78edbfc8db..22f1049056 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 @@ -2908,12 +2912,10 @@ 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; @@ -2923,7 +2925,6 @@ 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. */ @@ -2940,8 +2941,6 @@ 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); } diff --git a/manual/tunables.texi b/manual/tunables.texi index d8c22dd29f..74ae253ebf 100644 --- a/manual/tunables.texi +++ b/manual/tunables.texi @@ -188,7 +188,7 @@ per-thread cache. The default (and maximum) value is 1032 bytes on @deftp Tunable glibc.malloc.tcache_count The maximum number of chunks of each size to cache. The default is 7. -The upper limit is 127. If set to zero, the per-thread cache is effectively +The upper limit is 65535. If set to zero, the per-thread cache is effectively disabled. The approximate maximum overhead of the per-thread cache is thus equal |