diff options
| author | Uros Bizjak | 2024-05-28 16:43:14 +0200 |
|---|---|---|
| committer | Andrew Morton | 2024-07-03 19:30:02 -0700 |
| commit | f56810c94ca828ab5c223a3528cc44c823cace16 (patch) | |
| tree | 12e21d9706b1c8882425c2e17ab83e300f4aa93c /mm/vmalloc.c | |
| parent | 21664442be1bf79094dd9d21b8833acbfbd80ea7 (diff) | |
mm/vmalloc: use __this_cpu_try_cmpxchg() in preload_this_cpu_lock()
Use __this_cpu_try_cmpxchg() instead of __this_cpu_cmpxchg (*ptr, old,
new) == old in preload_this_cpu_lock(). x86 CMPXCHG instruction returns
success in ZF flag, so this change saves a compare after cmpxchg.
The generated code improves from:
4bb6: 48 85 f6 test %rsi,%rsi
4bb9: 0f 84 10 fa ff ff je 45cf <...>
4bbf: 4c 89 e8 mov %r13,%rax
4bc2: 65 48 0f b1 35 00 00 cmpxchg %rsi,%gs:0x0(%rip)
4bc9: 00 00
4bcb: 48 85 c0 test %rax,%rax
4bce: 0f 84 fb f9 ff ff je 45cf <...>
to:
4bb6: 48 85 f6 test %rsi,%rsi
4bb9: 0f 84 10 fa ff ff je 45cf <...>
4bbf: 4c 89 e8 mov %r13,%rax
4bc2: 65 48 0f b1 35 00 00 cmpxchg %rsi,%gs:0x0(%rip)
4bc9: 00 00
4bcb: 0f 84 fe f9 ff ff je 45cf <...>
No functional change intended.
Link: https://lkml.kernel.org/r/20240528144345.5980-2-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/vmalloc.c')
| -rw-r--r-- | mm/vmalloc.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/mm/vmalloc.c b/mm/vmalloc.c index d0cbdd7c1e5b..4d9e1cbba8c2 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1816,7 +1816,7 @@ static void free_vmap_area(struct vmap_area *va) static inline void preload_this_cpu_lock(spinlock_t *lock, gfp_t gfp_mask, int node) { - struct vmap_area *va = NULL; + struct vmap_area *va = NULL, *tmp; /* * Preload this CPU with one extra vmap_area object. It is used @@ -1832,7 +1832,8 @@ preload_this_cpu_lock(spinlock_t *lock, gfp_t gfp_mask, int node) spin_lock(lock); - if (va && __this_cpu_cmpxchg(ne_fit_preload_node, NULL, va)) + tmp = NULL; + if (va && !__this_cpu_try_cmpxchg(ne_fit_preload_node, &tmp, va)) kmem_cache_free(vmap_area_cachep, va); } |