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virtio_net: reduce alignment for buffers

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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: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2017-03-06 22:21:35 +02:00
parent 680557cf79
commit e377fcc848
1 changed files with 1 additions and 12 deletions
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13
drivers/net/virtio_net.c
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@ -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,