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io_uring/zcrx: improve rqe cache alignment 

Refill queue entries are 16B structures, but because of the ring header
placement, they're 8B aligned but not naturally / 16B aligned, which
means some of them span across 2 cache lines. Push rqes to a new cache
line.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
pull/1354/merge
Pavel Begunkov 2025-09-16 15:27:44 +01:00 committed by Jens Axboe
parent 1b3aa39007
commit 9eb3c57178
1 changed files with 5 additions and 4 deletions
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9
io_uring/zcrx.c
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@ -352,7 +352,7 @@ static int io_allocate_rbuf_ring(struct io_zcrx_ifq *ifq,
void *ptr;
int ret;
off = sizeof(struct io_uring);
off = ALIGN(sizeof(struct io_uring), L1_CACHE_BYTES);
size = off + sizeof(struct io_uring_zcrx_rqe) * reg->rq_entries;
if (size > rd->size)
return -EINVAL;
@ -367,6 +367,10 @@ static int io_allocate_rbuf_ring(struct io_zcrx_ifq *ifq,
ptr = io_region_get_ptr(&ifq->region);
ifq->rq_ring = (struct io_uring *)ptr;
ifq->rqes = (struct io_uring_zcrx_rqe *)(ptr + off);
reg->offsets.head = offsetof(struct io_uring, head);
reg->offsets.tail = offsetof(struct io_uring, tail);
reg->offsets.rqes = off;
return 0;
}
@ -618,9 +622,6 @@ int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
goto err;
ifq->if_rxq = reg.if_rxq;
reg.offsets.rqes = sizeof(struct io_uring);
reg.offsets.head = offsetof(struct io_uring, head);
reg.offsets.tail = offsetof(struct io_uring, tail);
reg.zcrx_id = id;
scoped_guard(mutex, &ctx->mmap_lock) {