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Commit e377fcc8 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin
Browse files

virtio_net: reduce alignment for buffers 



We don't need to align length to any particular
value anymore. Aligning to L1 cache size probably
sill makes sense to reduce false sharing.

Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 680557cf

drivers/net/virtio_net.c

+1 −12
Original line number Diff line number Diff line
@@ -53,17 +53,6 @@ module_param(gso, bool, 0444); 
 */

DECLARE_EWMA(pkt_len, 0, 64)



/* With mergeable buffers we align buffer address and use the low bits to

 * encode its true size. Buffer size is up to 1 page so we need to align to

 * square root of page size to ensure we reserve enough bits to encode the true

 * size.

 */

#define MERGEABLE_BUFFER_MIN_ALIGN_SHIFT ((PAGE_SHIFT + 1) / 2)



/* Minimum alignment for mergeable packet buffers. */

#define MERGEABLE_BUFFER_ALIGN max(L1_CACHE_BYTES, \

				   1 << MERGEABLE_BUFFER_MIN_ALIGN_SHIFT)



#define VIRTNET_DRIVER_VERSION "1.0.0"



struct virtnet_stats {
@@ -849,7 +838,7 @@ static unsigned int get_mergeable_buf_len(struct ewma_pkt_len *avg_pkt_len) 


	len = hdr_len + clamp_t(unsigned int, ewma_pkt_len_read(avg_pkt_len),

			GOOD_PACKET_LEN, PAGE_SIZE - hdr_len);

	return ALIGN(len, MERGEABLE_BUFFER_ALIGN);

	return ALIGN(len, L1_CACHE_BYTES);

}



static int add_recvbuf_mergeable(struct virtnet_info *vi,