[ovs-dev] [RFC v5 3/8] dp-packet: Add support for multi-seg mbufs
Tiago Lam
tiago.lam at intel.com
Tue May 1 17:02:09 UTC 2018
From: Mark Kavanagh <mark.b.kavanagh at intel.com>
Some functions in dp-packet assume that the data held by a dp_packet is
contiguous, and perform operations such as pointer arithmetic under that
assumption. However, with the introduction of multi-segment mbufs, where
data is non-contiguous, such assumptions are no longer possible. Thus,
dp_packet_put_init(), dp_packet_shift(), dp_packet_tail(),
dp_packet_end() and dp_packet_at() were modified to take multi-segment
mbufs into account.
Both dp_packet_put_uninit() and dp_packet_shift() are, in their current
implementation, operating on the data buffer of a dp_packet as if it
were contiguous, which in the case of multi-segment mbufs means they
operate on the first mbuf in the chain. However, in the case of
dp_packet_put_uninit(), for example, it is the data length of the last
mbuf in the mbuf chain that should be adjusted. Both functions have thus
been modified to support multi-segment mbufs.
Finally, dp_packet_tail(), dp_packet_end() and dp_packet_at() were also
modified to operate differently when dealing with multi-segment mbufs,
and now iterate over the non-contiguous data buffers for their
calculations.
Co-authored-by: Tiago Lam <tiago.lam at intel.com>
Signed-off-by: Mark Kavanagh <mark.b.kavanagh at intel.com>
Signed-off-by: Tiago Lam <tiago.lam at intel.com>
---
lib/dp-packet.c | 44 ++++++++++++++++-
lib/dp-packet.h | 142 ++++++++++++++++++++++++++++++++++++++----------------
lib/netdev-dpdk.c | 8 +--
3 files changed, 147 insertions(+), 47 deletions(-)
diff --git a/lib/dp-packet.c b/lib/dp-packet.c
index 443c225..fd9fad0 100644
--- a/lib/dp-packet.c
+++ b/lib/dp-packet.c
@@ -298,10 +298,33 @@ dp_packet_prealloc_headroom(struct dp_packet *b, size_t size)
/* Shifts all of the data within the allocated space in 'b' by 'delta' bytes.
* For example, a 'delta' of 1 would cause each byte of data to move one byte
* forward (from address 'p' to 'p+1'), and a 'delta' of -1 would cause each
- * byte to move one byte backward (from 'p' to 'p-1'). */
+ * byte to move one byte backward (from 'p' to 'p-1').
+ * Note for DPBUF_DPDK(XXX): The shift can only move within a size of RTE_
+ * PKTMBUF_HEADROOM, to either left or right, which is usually defined as 128
+ * bytes.
+ */
void
dp_packet_shift(struct dp_packet *b, int delta)
{
+#ifdef DPDK_NETDEV
+ if (b->source == DPBUF_DPDK) {
+ ovs_assert(delta > 0 ? delta <= dp_packet_headroom(b)
+ : delta < 0 ? -delta <= dp_packet_headroom(b)
+ : true);
+
+ if (delta != 0) {
+ struct rte_mbuf *mbuf = CONST_CAST(struct rte_mbuf *, &b->mbuf);
+
+ if (delta > 0) {
+ rte_pktmbuf_prepend(mbuf, delta);
+ } else {
+ rte_pktmbuf_prepend(mbuf, delta);
+ }
+ }
+
+ return;
+ }
+#endif
ovs_assert(delta > 0 ? delta <= dp_packet_tailroom(b)
: delta < 0 ? -delta <= dp_packet_headroom(b)
: true);
@@ -315,14 +338,31 @@ dp_packet_shift(struct dp_packet *b, int delta)
/* Appends 'size' bytes of data to the tail end of 'b', reallocating and
* copying its data if necessary. Returns a pointer to the first byte of the
- * new data, which is left uninitialized. */
+ * new data, which is left uninitialized.
+ * Note for DPBUF_DPDK(XXX): In this case there must be enough tailroom to put
+ * the data in, otherwise this will result in a call to ovs_abort(). */
void *
dp_packet_put_uninit(struct dp_packet *b, size_t size)
{
void *p;
dp_packet_prealloc_tailroom(b, size);
p = dp_packet_tail(b);
+#ifdef DPDK_NETDEV
+ if (b->source == DPBUF_DPDK) {
+ /* In the case of multi-segment mbufs, the data length of the last mbuf
+ * should be adjusted by 'size' bytes. The packet length of the entire
+ * mbuf chain (stored in the first mbuf of said chain) is adjusted in
+ * the normal execution path below.
+ */
+ struct rte_mbuf *buf = &(b->mbuf);
+ buf = rte_pktmbuf_lastseg(buf);
+
+ buf->data_len += size;
+ }
+#endif
+
dp_packet_set_size(b, dp_packet_size(b) + size);
+
return p;
}
diff --git a/lib/dp-packet.h b/lib/dp-packet.h
index 9bfb7b7..d6512cf 100644
--- a/lib/dp-packet.h
+++ b/lib/dp-packet.h
@@ -55,12 +55,12 @@ struct dp_packet {
struct rte_mbuf mbuf; /* DPDK mbuf */
#else
void *base_; /* First byte of allocated space. */
- uint16_t allocated_; /* Number of bytes allocated. */
uint16_t data_ofs; /* First byte actually in use. */
uint32_t size_; /* Number of bytes in use. */
uint32_t rss_hash; /* Packet hash. */
bool rss_hash_valid; /* Is the 'rss_hash' valid? */
#endif
+ uint16_t allocated_; /* Number of bytes allocated. */
enum dp_packet_source source; /* Source of memory allocated as 'base'. */
/* All the following elements of this struct are copied in a single call
@@ -133,6 +133,8 @@ static inline void *dp_packet_at(const struct dp_packet *, size_t offset,
size_t size);
static inline void *dp_packet_at_assert(const struct dp_packet *,
size_t offset, size_t size);
+static inline void * dp_packet_at_offset(const struct dp_packet *b,
+ size_t offset);
static inline void *dp_packet_tail(const struct dp_packet *);
static inline void *dp_packet_end(const struct dp_packet *);
@@ -180,40 +182,6 @@ dp_packet_delete(struct dp_packet *b)
}
}
-/* If 'b' contains at least 'offset + size' bytes of data, returns a pointer to
- * byte 'offset'. Otherwise, returns a null pointer. */
-static inline void *
-dp_packet_at(const struct dp_packet *b, size_t offset, size_t size)
-{
- return offset + size <= dp_packet_size(b)
- ? (char *) dp_packet_data(b) + offset
- : NULL;
-}
-
-/* Returns a pointer to byte 'offset' in 'b', which must contain at least
- * 'offset + size' bytes of data. */
-static inline void *
-dp_packet_at_assert(const struct dp_packet *b, size_t offset, size_t size)
-{
- ovs_assert(offset + size <= dp_packet_size(b));
- return ((char *) dp_packet_data(b)) + offset;
-}
-
-/* Returns a pointer to byte following the last byte of data in use in 'b'. */
-static inline void *
-dp_packet_tail(const struct dp_packet *b)
-{
- return (char *) dp_packet_data(b) + dp_packet_size(b);
-}
-
-/* Returns a pointer to byte following the last byte allocated for use (but
- * not necessarily in use) in 'b'. */
-static inline void *
-dp_packet_end(const struct dp_packet *b)
-{
- return (char *) dp_packet_base(b) + dp_packet_get_allocated(b);
-}
-
/* Returns the number of bytes of headroom in 'b', that is, the number of bytes
* of unused space in dp_packet 'b' before the data that is in use. (Most
* commonly, the data in a dp_packet is at its beginning, and thus the
@@ -454,18 +422,107 @@ __packet_set_data(struct dp_packet *b, uint16_t v)
b->mbuf.data_off = v;
}
-static inline uint16_t
-dp_packet_get_allocated(const struct dp_packet *b)
+static inline void *
+dp_packet_at_offset(const struct dp_packet *b, size_t offset)
{
- return b->mbuf.buf_len;
+ if (b->source == DPBUF_DPDK) {
+ struct rte_mbuf *buf = CONST_CAST(struct rte_mbuf *, &b->mbuf);
+
+ while (buf && offset > buf->data_len) {
+ offset -= buf->data_len;
+
+ buf = buf->next;
+ }
+ return buf ? rte_pktmbuf_mtod_offset(buf, char *, offset) : NULL;
+ } else {
+ return (char *) dp_packet_data(b) + offset;
+ }
}
-static inline void
-dp_packet_set_allocated(struct dp_packet *b, uint16_t s)
+/* If 'b' contains at least 'offset + size' bytes of data, returns a pointer to
+ * byte 'offset'. Otherwise, returns a null pointer. */
+static inline void *
+dp_packet_at(const struct dp_packet *b, size_t offset, size_t size)
+{
+ return offset + size <= dp_packet_size(b)
+ ? dp_packet_at_offset(b, offset)
+ : NULL;
+}
+
+/* Returns a pointer to byte 'offset' in 'b', which must contain at least
+ * 'offset + size' bytes of data. */
+static inline void *
+dp_packet_at_assert(const struct dp_packet *b, size_t offset, size_t size)
{
- b->mbuf.buf_len = s;
+ ovs_assert(offset + size <= dp_packet_size(b));
+ return dp_packet_at_offset(b, offset);
+}
+
+/* Returns a pointer to byte following the last byte of data in use in 'b'. */
+static inline void *
+dp_packet_tail(const struct dp_packet *b)
+{
+ if (b->source == DPBUF_DPDK) {
+ struct rte_mbuf *buf = CONST_CAST(struct rte_mbuf *, &b->mbuf);
+
+ buf = rte_pktmbuf_lastseg(buf);
+
+ return rte_pktmbuf_mtod_offset(buf, char *, buf->data_len);
+ } else {
+ return (char *) dp_packet_data(b) + dp_packet_size(b);
+ }
+}
+
+/* Returns a pointer to byte following the last byte allocated for use (but
+ * not necessarily in use) in 'b'. */
+static inline void *
+dp_packet_end(const struct dp_packet *b)
+{
+ if (b->source == DPBUF_DPDK) {
+ struct rte_mbuf *buf = CONST_CAST(struct rte_mbuf *, &(b->mbuf));
+
+ buf = rte_pktmbuf_lastseg(buf);
+
+ return rte_pktmbuf_mtod(buf, char *) + buf->buf_len;
+ } else {
+ return (char *) dp_packet_base(b) + dp_packet_get_allocated(b);
+ }
}
#else
+/* If 'b' contains at least 'offset + size' bytes of data, returns a pointer to
+ * byte 'offset'. Otherwise, returns a null pointer. */
+static inline void *
+dp_packet_at(const struct dp_packet *b, size_t offset, size_t size)
+{
+ return offset + size <= dp_packet_size(b)
+ ? (char *) dp_packet_data(b) + offset
+ : NULL;
+}
+
+/* Returns a pointer to byte 'offset' in 'b', which must contain at least
+ * 'offset + size' bytes of data. */
+static inline void *
+dp_packet_at_assert(const struct dp_packet *b, size_t offset, size_t size)
+{
+ ovs_assert(offset + size <= dp_packet_size(b));
+ return ((char *) dp_packet_data(b)) + offset;
+}
+
+/* Returns a pointer to byte following the last byte of data in use in 'b'. */
+static inline void *
+dp_packet_tail(const struct dp_packet *b)
+{
+ return (char *) dp_packet_data(b) + dp_packet_size(b);
+}
+
+/* Returns a pointer to byte following the last byte allocated for use (but
+ * not necessarily in use) in 'b'. */
+static inline void *
+dp_packet_end(const struct dp_packet *b)
+{
+ return (char *) dp_packet_base(b) + dp_packet_get_allocated(b);
+}
+
static inline void *
dp_packet_base(const struct dp_packet *b)
{
@@ -502,6 +559,8 @@ __packet_set_data(struct dp_packet *b, uint16_t v)
b->data_ofs = v;
}
+#endif
+
static inline uint16_t
dp_packet_get_allocated(const struct dp_packet *b)
{
@@ -513,7 +572,6 @@ dp_packet_set_allocated(struct dp_packet *b, uint16_t s)
{
b->allocated_ = s;
}
-#endif
static inline void
dp_packet_reset_cutlen(struct dp_packet *b)
diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
index 648a1de..7008492 100644
--- a/lib/netdev-dpdk.c
+++ b/lib/netdev-dpdk.c
@@ -506,13 +506,14 @@ free_dpdk_buf(struct dp_packet *p)
static void
ovs_rte_pktmbuf_init(struct rte_mempool *mp OVS_UNUSED,
- void *opaque_arg OVS_UNUSED,
+ void *opaque_arg,
void *_p,
unsigned i OVS_UNUSED)
{
struct rte_mbuf *pkt = _p;
+ uint16_t allocated = *(uint16_t *) opaque_arg;
- dp_packet_init_dpdk((struct dp_packet *) pkt, pkt->buf_len);
+ dp_packet_init_dpdk((struct dp_packet *) pkt, allocated);
}
static int
@@ -643,7 +644,8 @@ dpdk_mp_create(struct netdev_dpdk *dev, uint16_t mbuf_pkt_data_len)
* rte_mbuf part of each dp_packet. Some OvS specific fields
* of the packet still need to be initialized by
* ovs_rte_pktmbuf_init. */
- rte_mempool_obj_iter(mp, ovs_rte_pktmbuf_init, NULL);
+ uint16_t allocated_bytes = dpdk_buf_size(dev->requested_mtu);
+ rte_mempool_obj_iter(mp, ovs_rte_pktmbuf_init, &allocated_bytes);
} else if (rte_errno == EEXIST) {
/* A mempool with the same name already exists. We just
* retrieve its pointer to be returned to the caller. */
--
2.7.4
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