+ Santosh
>From: [email protected] [mailto:[email protected]]
>On Behalf Of Mark Kavanagh
>Sent: Tuesday, November 21, 2017 6:29 PM
>To: [email protected]; [email protected]
>Subject: [ovs-dev] [RFC PATCH v3 1/8] netdev-dpdk: simplify mbuf sizing
>
>When calculating the mbuf data_room_size (i.e. the size of actual
>packet data that an mbuf can accomodate), it is possible to simply
>use the value calculated by dpdk_buf_size() as a parameter to
>rte_pktmbuf_pool_create(). This simplifies mbuf sizing considerably.
>This patch removes the related size conversions and macros, which
>are no longer needed.
>
>The benefits of this approach are threefold:
>- the mbuf sizing code is much simpler, and more readable.
>- mbuf size will always be cache-aligned [1], satisfying that
> requirement of specific PMDs (vNIC thunderx, for example).
>- the maximum amount of data that each mbuf contains may now be
> calculated as mbuf->buf_len - mbuf->data_off. This is important
> in the case of multi-segment jumbo frames.
>
>[1] (this is true since mbuf size is now always a multiple
> of 1024, + 128B RTE_PKTMBUF_HEADROOM + 704B dp_packet).
Santosh, I've just spotted that the cacheline size for thunderx is defined as
128B, as opposed to 64.
==>
config/defconfig_arm64-thunderx-linuxapp-gcc:36:CONFIG_RTE_CACHE_LINE_SIZE=128
Apologies for the oversight - I'd be very interested to hear your thoughts on
this patch.
Thanks in advance,
Mark
>
>Fixes: 4be4d22 ("netdev-dpdk: clean up mbuf initialization")
>Fixes: 31b88c9 ("netdev-dpdk: round up mbuf_size to cache_line_size")
>Signed-off-by: Mark Kavanagh <[email protected]>
>---
> lib/netdev-dpdk.c | 22 ++++++++--------------
> 1 file changed, 8 insertions(+), 14 deletions(-)
>
>diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
>index 8906423..c5eb851 100644
>--- a/lib/netdev-dpdk.c
>+++ b/lib/netdev-dpdk.c
>@@ -81,12 +81,6 @@ static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5,
>20);
> + (2 * VLAN_HEADER_LEN))
> #define MTU_TO_FRAME_LEN(mtu) ((mtu) + ETHER_HDR_LEN + ETHER_CRC_LEN)
> #define MTU_TO_MAX_FRAME_LEN(mtu) ((mtu) + ETHER_HDR_MAX_LEN)
>-#define FRAME_LEN_TO_MTU(frame_len) ((frame_len) \
>- - ETHER_HDR_LEN - ETHER_CRC_LEN)
>-#define MBUF_SIZE(mtu) ROUND_UP((MTU_TO_MAX_FRAME_LEN(mtu) \
>- + sizeof(struct dp_packet) \
>- + RTE_PKTMBUF_HEADROOM), \
>- RTE_CACHE_LINE_SIZE)
> #define NETDEV_DPDK_MBUF_ALIGN 1024
> #define NETDEV_DPDK_MAX_PKT_LEN 9728
>
>@@ -447,7 +441,7 @@ is_dpdk_class(const struct netdev_class *class)
> * behaviour, which reduces performance. To prevent this, use a buffer size
> * that is closest to 'mtu', but which satisfies the aforementioned criteria.
> */
>-static uint32_t
>+static uint16_t
> dpdk_buf_size(int mtu)
> {
> return ROUND_UP((MTU_TO_MAX_FRAME_LEN(mtu) + RTE_PKTMBUF_HEADROOM),
>@@ -486,7 +480,7 @@ ovs_rte_pktmbuf_init(struct rte_mempool *mp OVS_UNUSED,
> * - a new mempool was just created;
> * - a matching mempool already exists. */
> static struct rte_mempool *
>-dpdk_mp_create(struct netdev_dpdk *dev, int mtu)
>+dpdk_mp_create(struct netdev_dpdk *dev, uint16_t frame_len)
> {
> char mp_name[RTE_MEMPOOL_NAMESIZE];
> const char *netdev_name = netdev_get_name(&dev->up);
>@@ -513,12 +507,12 @@ dpdk_mp_create(struct netdev_dpdk *dev, int mtu)
> * longer than RTE_MEMPOOL_NAMESIZE. */
> int ret = snprintf(mp_name, RTE_MEMPOOL_NAMESIZE,
> "ovs%08x%02d%05d%07u",
>- hash, socket_id, mtu, n_mbufs);
>+ hash, socket_id, frame_len, n_mbufs);
> if (ret < 0 || ret >= RTE_MEMPOOL_NAMESIZE) {
> VLOG_DBG("snprintf returned %d. "
> "Failed to generate a mempool name for \"%s\". "
>- "Hash:0x%x, socket_id: %d, mtu:%d, mbufs:%u.",
>- ret, netdev_name, hash, socket_id, mtu, n_mbufs);
>+ "Hash:0x%x, socket_id: %d, frame length:%d, mbufs:%u.",
>+ ret, netdev_name, hash, socket_id, frame_len, n_mbufs);
> break;
> }
>
>@@ -529,7 +523,7 @@ dpdk_mp_create(struct netdev_dpdk *dev, int mtu)
>
> mp = rte_pktmbuf_pool_create(mp_name, n_mbufs, MP_CACHE_SZ,
> sizeof (struct dp_packet) - sizeof (struct rte_mbuf),
>- MBUF_SIZE(mtu) - sizeof(struct dp_packet), socket_id);
>+ frame_len + RTE_PKTMBUF_HEADROOM, socket_id);
>
> if (mp) {
> VLOG_DBG("Allocated \"%s\" mempool with %u mbufs",
>@@ -582,11 +576,11 @@ static int
> netdev_dpdk_mempool_configure(struct netdev_dpdk *dev)
> OVS_REQUIRES(dev->mutex)
> {
>- uint32_t buf_size = dpdk_buf_size(dev->requested_mtu);
>+ uint16_t buf_size = dpdk_buf_size(dev->requested_mtu);
> struct rte_mempool *mp;
> int ret = 0;
>
>- mp = dpdk_mp_create(dev, FRAME_LEN_TO_MTU(buf_size));
>+ mp = dpdk_mp_create(dev, buf_size);
> if (!mp) {
> VLOG_ERR("Failed to create memory pool for netdev "
> "%s, with MTU %d on socket %d: %s\n",
>--
>1.9.3
>
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