[dpdk-dev,memnic,6/7] pmd: add branch hint in recv/xmit
Commit Message
From: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
To reduce instruction cache miss, add branch condition hints into
recv/xmit functions. This improves a bit performance.
We can see performance improvements with memnic-tester.
Using Xeon E5-2697 v2 @ 2.70GHz, 4 vCPU.
size | before | after
64 | 5.54Mpps | 5.55Mpps
128 | 5.46Mpps | 5.44Mpps
256 | 5.21Mpps | 5.22Mpps
512 | 4.50Mpps | 4.52Mpps
1024 | 3.71Mpps | 3.73Mpps
1280 | 3.21Mpps | 3.22Mpps
1518 | 2.92Mpps | 2.93Mpps
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Reviewed-by: Hayato Momma <h-momma@ce.jp.nec.com>
---
pmd/pmd_memnic.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
@@ -289,26 +289,26 @@ static uint16_t memnic_recv_pkts(void *rx_queue,
int idx, next;
struct rte_eth_stats *st = &adapter->stats[rte_lcore_id()];
- if (!adapter->nic->hdr.valid)
+ if (unlikely(!adapter->nic->hdr.valid))
return 0;
pkts = bytes = errs = 0;
idx = adapter->up_idx;
for (nr = 0; nr < nb_pkts; nr++) {
p = &data->packets[idx];
- if (p->status != MEMNIC_PKT_ST_FILLED)
+ if (unlikely(p->status != MEMNIC_PKT_ST_FILLED))
break;
/* prefetch the next area */
next = idx;
- if (++next >= MEMNIC_NR_PACKET)
+ if (unlikely(++next >= MEMNIC_NR_PACKET))
next = 0;
rte_prefetch0(&data->packets[next]);
- if (p->len > framesz) {
+ if (unlikely(p->len > framesz)) {
errs++;
goto drop;
}
mb = rte_pktmbuf_alloc(adapter->mp);
- if (!mb)
+ if (unlikely(!mb))
break;
rte_memcpy(rte_pktmbuf_mtod(mb, void *), p->data, p->len);
@@ -350,7 +350,7 @@ static uint16_t memnic_xmit_pkts(void *tx_queue,
uint64_t pkts, bytes, errs;
uint32_t framesz = adapter->framesz;
- if (!adapter->nic->hdr.valid)
+ if (unlikely(!adapter->nic->hdr.valid))
return 0;
pkts = bytes = errs = 0;
@@ -360,7 +360,7 @@ static uint16_t memnic_xmit_pkts(void *tx_queue,
struct rte_mbuf *sg;
void *ptr;
- if (pkt_len > framesz) {
+ if (unlikely(pkt_len > framesz)) {
errs++;
break;
}
@@ -379,7 +379,7 @@ retry:
goto retry;
}
- if (idx != ACCESS_ONCE(adapter->down_idx)) {
+ if (unlikely(idx != ACCESS_ONCE(adapter->down_idx))) {
/*
* host freed this and got false positive,
* need to recover the status and retry.
@@ -388,7 +388,7 @@ retry:
goto retry;
}
- if (++idx >= MEMNIC_NR_PACKET)
+ if (unlikely(++idx >= MEMNIC_NR_PACKET))
idx = 0;
adapter->down_idx = idx;