Do you see any performance improvements with these changes?
-----Original Message-----
From: dev <dev-boun...@dpdk.org> On Behalf Of Morten Brørup
Sent: Monday, July 23, 2018 8:54 AM
To: Olivier Matz <olivier.m...@6wind.com>
Cc: dev@dpdk.org
Subject: [dpdk-dev] rte_mbuf library likely()/unlikely()
Hi Olivier,
I noticed that __rte_pktmbuf_read() could do with an unlikely(), so I went
through the entire library. Here are my suggested modifications.
diff -bu rte_mbuf.c.orig rte_mbuf.c
--- rte_mbuf.c.orig 2018-07-23 15:13:22.000000000 +0200
+++ rte_mbuf.c 2018-07-23 15:32:53.000000000 +0200
@@ -173,19 +173,19 @@
{
unsigned int nb_segs, pkt_len;
- if (m == NULL)
+ if (unlikely(m == NULL))
rte_panic("mbuf is NULL\n");
/* generic checks */
- if (m->pool == NULL)
+ if (unlikely(m->pool == NULL))
rte_panic("bad mbuf pool\n");
- if (m->buf_iova == 0)
+ if (unlikely(m->buf_iova == 0))
rte_panic("bad IO addr\n");
- if (m->buf_addr == NULL)
+ if (unlikely(m->buf_addr == NULL))
rte_panic("bad virt addr\n");
uint16_t cnt = rte_mbuf_refcnt_read(m);
- if ((cnt == 0) || (cnt == UINT16_MAX))
+ if (unlikely((cnt == 0) || (cnt == UINT16_MAX)))
rte_panic("bad ref cnt\n");
/* nothing to check for sub-segments */
@@ -193,7 +193,7 @@
return;
/* data_len is supposed to be not more than pkt_len */
- if (m->data_len > m->pkt_len)
+ if (unlikely(m->data_len > m->pkt_len))
rte_panic("bad data_len\n");
nb_segs = m->nb_segs;
@@ -204,9 +204,9 @@
pkt_len -= m->data_len;
} while ((m = m->next) != NULL);
- if (nb_segs)
+ if (unlikely(nb_segs))
rte_panic("bad nb_segs\n");
- if (pkt_len)
+ if (unlikely(pkt_len))
rte_panic("bad pkt_len\n");
}
@@ -249,7 +249,7 @@
const struct rte_mbuf *seg = m;
uint32_t buf_off = 0, copy_len;
- if (off + len > rte_pktmbuf_pkt_len(m))
+ if (unlikely(off + len > rte_pktmbuf_pkt_len(m)))
return NULL;
while (off >= rte_pktmbuf_data_len(seg)) {
@@ -257,7 +257,7 @@
seg = seg->next;
}
- if (off + len <= rte_pktmbuf_data_len(seg))
+ if (likely(off + len <= rte_pktmbuf_data_len(seg)))
return rte_pktmbuf_mtod_offset(seg, char *, off);
/* rare case: header is split among several segments */
@@ -344,7 +344,7 @@
unsigned int i;
int ret;
- if (buflen == 0)
+ if (unlikely(buflen == 0))
return -1;
buf[0] = '\0';
@@ -355,9 +355,9 @@
if (name == NULL)
name = rx_flags[i].default_name;
ret = snprintf(buf, buflen, "%s ", name);
- if (ret < 0)
+ if (unlikely(ret < 0))
return -1;
- if ((size_t)ret >= buflen)
+ if (unlikely((size_t)ret >= buflen))
return -1;
buf += ret;
buflen -= ret;
@@ -440,7 +440,7 @@
unsigned int i;
int ret;
- if (buflen == 0)
+ if (unlikely(buflen == 0))
return -1;
buf[0] = '\0';
@@ -451,9 +451,9 @@
if (name == NULL)
name = tx_flags[i].default_name;
ret = snprintf(buf, buflen, "%s ", name);
- if (ret < 0)
+ if (unlikely(ret < 0))
return -1;
- if ((size_t)ret >= buflen)
+ if (unlikely((size_t)ret >= buflen))
return -1;
buf += ret;
buflen -= ret;
diff -bu rte_mbuf.h.orig rte_mbuf.h
--- rte_mbuf.h.orig 2018-07-23 15:13:26.000000000 +0200
+++ rte_mbuf.h 2018-07-23 15:24:25.000000000 +0200
@@ -1007,7 +1007,7 @@
{
struct rte_mbuf *m;
- if (rte_mempool_get(mp, (void **)&m) < 0)
+ if (unlikely(rte_mempool_get(mp, (void **)&m) < 0))
return NULL;
MBUF_RAW_ALLOC_CHECK(m);
return m;
@@ -1268,7 +1268,7 @@
static inline struct rte_mbuf *rte_pktmbuf_alloc(struct rte_mempool *mp)
{
struct rte_mbuf *m;
- if ((m = rte_mbuf_raw_alloc(mp)) != NULL)
+ if (likely((m = rte_mbuf_raw_alloc(mp)) != NULL))
rte_pktmbuf_reset(m);
return m;
}
@@ -1696,7 +1696,7 @@
{
struct rte_mbuf *m_next;
- if (m != NULL)
+ if (likely(m != NULL))
__rte_mbuf_sanity_check(m, 1);
while (m != NULL) {
@@ -2099,7 +2099,7 @@
struct rte_mbuf *cur_tail;
/* Check for number-of-segments-overflow */
- if (head->nb_segs + tail->nb_segs > RTE_MBUF_MAX_NB_SEGS)
+ if (unlikely(head->nb_segs + tail->nb_segs > RTE_MBUF_MAX_NB_SEGS))
return -EOVERFLOW;
/* Chain 'tail' onto the old tail */
@@ -2147,28 +2147,28 @@
m->outer_l3_len;
/* Headers are fragmented */
- if (rte_pktmbuf_data_len(m) < inner_l3_offset + m->l3_len + m->l4_len)
+ if (unlikely(rte_pktmbuf_data_len(m) < inner_l3_offset + m->l3_len +
m->l4_len))
return -ENOTSUP;
/* IP checksum can be counted only for IPv4 packet */
- if ((ol_flags & PKT_TX_IP_CKSUM) && (ol_flags & PKT_TX_IPV6))
+ if (unlikely((ol_flags & PKT_TX_IP_CKSUM) && (ol_flags & PKT_TX_IPV6)))
return -EINVAL;
/* IP type not set when required */
if (ol_flags & (PKT_TX_L4_MASK | PKT_TX_TCP_SEG))
- if (!(ol_flags & (PKT_TX_IPV4 | PKT_TX_IPV6)))
+ if (unlikely(!(ol_flags & (PKT_TX_IPV4 | PKT_TX_IPV6))))
return -EINVAL;
/* Check requirements for TSO packet */
if (ol_flags & PKT_TX_TCP_SEG)
- if ((m->tso_segsz == 0) ||
+ if (unlikely((m->tso_segsz == 0) ||
((ol_flags & PKT_TX_IPV4) &&
- !(ol_flags & PKT_TX_IP_CKSUM)))
+ !(ol_flags & PKT_TX_IP_CKSUM))))
return -EINVAL;
/* PKT_TX_OUTER_IP_CKSUM set for non outer IPv4 packet. */
- if ((ol_flags & PKT_TX_OUTER_IP_CKSUM) &&
- !(ol_flags & PKT_TX_OUTER_IPV4))
+ if (unlikely((ol_flags & PKT_TX_OUTER_IP_CKSUM) &&
+ !(ol_flags & PKT_TX_OUTER_IPV4)))
return -EINVAL;
return 0;
diff -bu rte_mbuf_ptype.c.orig rte_mbuf_ptype.c
--- rte_mbuf_ptype.c.orig 2018-07-23 15:45:49.000000000 +0200
+++ rte_mbuf_ptype.c 2018-07-23 15:44:59.000000000 +0200
@@ -118,15 +118,15 @@
{
int ret;
- if (buflen == 0)
+ if (unlikely(buflen == 0))
return -1;
buf[0] = '\0';
if ((ptype & RTE_PTYPE_ALL_MASK) == RTE_PTYPE_UNKNOWN) {
ret = snprintf(buf, buflen, "UNKNOWN");
- if (ret < 0)
+ if (unlikely(ret < 0))
return -1;
- if ((size_t)ret >= buflen)
+ if (unlikely((size_t)ret >= buflen))
return -1;
return 0;
}
@@ -134,9 +134,9 @@
if ((ptype & RTE_PTYPE_L2_MASK) != 0) {
ret = snprintf(buf, buflen, "%s ",
rte_get_ptype_l2_name(ptype));
- if (ret < 0)
+ if (unlikely(ret < 0))
return -1;
- if ((size_t)ret >= buflen)
+ if (unlikely((size_t)ret >= buflen))
return -1;
buf += ret;
buflen -= ret;
@@ -144,9 +144,9 @@
if ((ptype & RTE_PTYPE_L3_MASK) != 0) {
ret = snprintf(buf, buflen, "%s ",
rte_get_ptype_l3_name(ptype));
- if (ret < 0)
+ if (unlikely(ret < 0))
return -1;
- if ((size_t)ret >= buflen)
+ if (unlikely((size_t)ret >= buflen))
return -1;
buf += ret;
buflen -= ret;
@@ -154,9 +154,9 @@
if ((ptype & RTE_PTYPE_L4_MASK) != 0) {
ret = snprintf(buf, buflen, "%s ",
rte_get_ptype_l4_name(ptype));
- if (ret < 0)
+ if (unlikely(ret < 0))
return -1;
- if ((size_t)ret >= buflen)
+ if (unlikely((size_t)ret >= buflen))
return -1;
buf += ret;
buflen -= ret;
@@ -164,9 +164,9 @@
if ((ptype & RTE_PTYPE_TUNNEL_MASK) != 0) {
ret = snprintf(buf, buflen, "%s ",
rte_get_ptype_tunnel_name(ptype));
- if (ret < 0)
+ if (unlikely(ret < 0))
return -1;
- if ((size_t)ret >= buflen)
+ if (unlikely((size_t)ret >= buflen))
return -1;
buf += ret;
buflen -= ret;
@@ -174,9 +174,9 @@
if ((ptype & RTE_PTYPE_INNER_L2_MASK) != 0) {
ret = snprintf(buf, buflen, "%s ",
rte_get_ptype_inner_l2_name(ptype));
- if (ret < 0)
+ if (unlikely(ret < 0))
return -1;
- if ((size_t)ret >= buflen)
+ if (unlikely((size_t)ret >= buflen))
return -1;
buf += ret;
buflen -= ret;
@@ -184,9 +184,9 @@
if ((ptype & RTE_PTYPE_INNER_L3_MASK) != 0) {
ret = snprintf(buf, buflen, "%s ",
rte_get_ptype_inner_l3_name(ptype));
- if (ret < 0)
+ if (unlikely(ret < 0))
return -1;
- if ((size_t)ret >= buflen)
+ if (unlikely((size_t)ret >= buflen))
return -1;
buf += ret;
buflen -= ret;
@@ -194,9 +194,9 @@
if ((ptype & RTE_PTYPE_INNER_L4_MASK) != 0) {
ret = snprintf(buf, buflen, "%s ",
rte_get_ptype_inner_l4_name(ptype));
- if (ret < 0)
+ if (unlikely(ret < 0))
return -1;
- if ((size_t)ret >= buflen)
+ if (unlikely((size_t)ret >= buflen))
return -1;
buf += ret;
buflen -= ret;
Med venlig hilsen / kind regards
Morten Brørup
CTO
SmartShare Systems A/S
Tonsbakken 16-18
DK-2740 Skovlunde
Denmark
Office +45 70 20 00 93
Direct +45 89 93 50 22
Mobile +45 25 40 82 12
m...@smartsharesystems.com <mailto:m...@smartsharesystems.com>
www.smartsharesystems.com <https://www.smartsharesystems.com/>
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