diff options
| author | Uladzislau Rezki (Sony) <urezki@gmail.com> | 2025-04-17 18:12:16 +0200 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-05-11 17:48:34 -0700 |
| commit | d0966120486833cd837feea9917b7ed06e74f58c (patch) | |
| tree | 2bdb913cbef699935e5db964c62387828f9c6463 /mm | |
| parent | 7a6fe5877745e46795865e3f6a0ae346671741a3 (diff) | |
vmalloc: align nr_vmalloc_pages and vmap_lazy_nr
Currently both atomics share one cache-line:
<snip>
...
ffffffff83eab400 b vmap_lazy_nr
ffffffff83eab408 b nr_vmalloc_pages
...
<snip>
those are global variables and they are only 8 bytes apart. Since they
are modified by different threads this causes a false sharing. This can
lead to a performance drop due to unnecessary cache invalidations.
After this patch it is aligned to a cache line boundary:
<snip>
...
ffffffff8260a600 d vmap_lazy_nr
ffffffff8260a640 d nr_vmalloc_pages
...
<snip>
Link: https://lkml.kernel.org/r/20250417161216.88318-4-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Adrian Huang <ahuang12@lenovo.com>
Tested-by: Adrian Huang <ahuang12@lenovo.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Christop Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/vmalloc.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/mm/vmalloc.c b/mm/vmalloc.c index dc33ebeb8b1b..3fd802134e4e 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1008,7 +1008,8 @@ static BLOCKING_NOTIFIER_HEAD(vmap_notify_list); static void drain_vmap_area_work(struct work_struct *work); static DECLARE_WORK(drain_vmap_work, drain_vmap_area_work); -static atomic_long_t nr_vmalloc_pages; +static __cacheline_aligned_in_smp atomic_long_t nr_vmalloc_pages; +static __cacheline_aligned_in_smp atomic_long_t vmap_lazy_nr; unsigned long vmalloc_nr_pages(void) { @@ -2117,8 +2118,6 @@ static unsigned long lazy_max_pages(void) return log * (32UL * 1024 * 1024 / PAGE_SIZE); } -static atomic_long_t vmap_lazy_nr = ATOMIC_LONG_INIT(0); - /* * Serialize vmap purging. There is no actual critical section protected * by this lock, but we want to avoid concurrent calls for performance |