diff options
| author | alc <alc@FreeBSD.org> | 2012-04-06 16:41:19 +0000 |
|---|---|---|
| committer | alc <alc@FreeBSD.org> | 2012-04-06 16:41:19 +0000 |
| commit | 84663665875313094ef5b78dfe6a2afd011ae12e (patch) | |
| tree | 9c7ebaacbb23f27b0829e91d9efeab2681a84393 /sys/amd64 | |
| parent | 9c79ae8eeae5c79b22d21b6b31cdb8cef3f8478a (diff) | |
| download | FreeBSD-src-84663665875313094ef5b78dfe6a2afd011ae12e.zip FreeBSD-src-84663665875313094ef5b78dfe6a2afd011ae12e.tar.gz | |
Micro-optimize free_pv_entry() for the expected case.
Diffstat (limited to 'sys/amd64')
| -rw-r--r-- | sys/amd64/amd64/pmap.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c index f293aaf..ff4f96b 100644 --- a/sys/amd64/amd64/pmap.c +++ b/sys/amd64/amd64/pmap.c @@ -2095,7 +2095,6 @@ pmap_collect(pmap_t locked_pmap, struct vpgqueues *vpq) } } - /* * free the pv_entry back to the free list */ @@ -2116,13 +2115,16 @@ free_pv_entry(pmap_t pmap, pv_entry_t pv) field = idx / 64; bit = idx % 64; pc->pc_map[field] |= 1ul << bit; - /* move to head of list */ - TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list); if (pc->pc_map[0] != PC_FREE0 || pc->pc_map[1] != PC_FREE1 || pc->pc_map[2] != PC_FREE2) { - TAILQ_INSERT_HEAD(&pmap->pm_pvchunk, pc, pc_list); + /* 98% of the time, pc is already at the head of the list. */ + if (__predict_false(pc != TAILQ_FIRST(&pmap->pm_pvchunk))) { + TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list); + TAILQ_INSERT_HEAD(&pmap->pm_pvchunk, pc, pc_list); + } return; } + TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list); PV_STAT(pv_entry_spare -= _NPCPV); PV_STAT(pc_chunk_count--); PV_STAT(pc_chunk_frees++); |
