io_uring/zcrx: put refill data into separate cache line

Refill queue lock and other bits are only used from the allocation path
on the rx softirq side, but it shares the cache line with other fields
like ctx that are used also in the "syscall" path, which causes cache
bouncing when softirq runs on a different CPU.

Separate them into different cache lines. The first one now contains
constant fields used by both contextx, followed by a line responsible
for refill queue data.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6d1f598e27d623c07fc49d6baee13089a9b1216c.1743848241.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/zcrx.h b/io_uring/zcrx.h
index 706cc7300780d6c3985fa61a8ce17a1d6660446f..b59c560d5d84a6951b4d34b470c6a4b96c71c5ed 100644 (file)
--- a/io_uring/zcrx.h
+++ b/io_uring/zcrx.h
@@ -26,11 +26,11 @@ struct io_zcrx_ifq {
        struct io_ring_ctx              *ctx;
        struct io_zcrx_area             *area;
 
+       spinlock_t                      rq_lock ____cacheline_aligned_in_smp;
        struct io_uring                 *rq_ring;
        struct io_uring_zcrx_rqe        *rqes;
-       u32                             rq_entries;
        u32                             cached_rq_head;
-       spinlock_t                      rq_lock;
+       u32                             rq_entries;
 
        u32                             if_rxq;
        struct device                   *dev;