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linux/mm/vmalloc.c
Uladzislau Rezki (Sony) d096612048 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>
2025-05-11 17:48:34 -07:00

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