@@ -130,7 +130,16 @@ struct page_pool {
bool has_init_callback;
- long frag_users;
+ /* The following block must stay within one cacheline. On 32-bit
+ * systems, sizeof(long) == sizeof(int), so that the block size is
+ * precisely ``4 * sizeof(long)``. On 64-bit systems, the actual size
+ * is ``2 * sizeof(long) + 2 * sizeof(int)``, i.e. 24 bytes, but the
+ * closest pow-2 to that is 32 bytes, which also equals to
+ * ``4 * sizeof(long)``, so just use that one for simplicity.
+ * Having it aligned to a cacheline boundary may be excessive and
+ * doesn't bring any good.
+ */
+ long frag_users __aligned(4 * sizeof(long));
struct page *frag_page;
unsigned int frag_offset;
u32 pages_state_hold_cnt;
After commit 5027ec19f104 ("net: page_pool: split the page_pool_params into fast and slow") that made &page_pool contain only "hot" params at the start, cacheline boundary chops frag API fields group in the middle again. To not bother with this each time fast params get expanded or shrunk, let's just align them to `4 * sizeof(long)`, the closest upper pow-2 to their actual size (2 longs + 2 ints). This ensures 16-byte alignment for the 32-bit architectures and 32-byte alignment for the 64-bit ones, excluding unnecessary false-sharing. Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com> --- include/net/page_pool/types.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)