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ionic: Shorten a Tx hotpath

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Perf was showing some hot spots in ionic_tx_descs_needed()
for TSO traffic.  Rework the function to return sooner where
possible.

Signed-off-by: Brett Creeley <brett.creeley@amd.com>
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Brett Creeley 2024-02-29 11:39:26 -08:00 committed by David S. Miller
parent 4d140402c6
commit 97085cda12
1 changed files with 10 additions and 5 deletions
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15
drivers/net/ethernet/pensando/ionic/ionic_txrx.c
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@ -1669,7 +1669,7 @@ static int ionic_tx(struct ionic_queue *q, struct sk_buff *skb)
static int ionic_tx_descs_needed(struct ionic_queue *q, struct sk_buff *skb)
{
struct ionic_tx_stats *stats = q_to_tx_stats(q);
int nr_frags = skb_shinfo(skb)->nr_frags;
bool too_many_frags = false;
skb_frag_t *frag;
int desc_bufs;
@ -1685,17 +1685,20 @@ static int ionic_tx_descs_needed(struct ionic_queue *q, struct sk_buff *skb)
/* Each desc is mss long max, so a descriptor for each gso_seg */
if (skb_is_gso(skb)) {
ndescs = skb_shinfo(skb)->gso_segs;
if (!nr_frags)
return ndescs;
} else {
ndescs = 1;
if (skb_shinfo(skb)->nr_frags > q->max_sg_elems) {
if (!nr_frags)
return ndescs;
if (unlikely(nr_frags > q->max_sg_elems)) {
too_many_frags = true;
goto linearize;
}
}
/* If non-TSO, or no frags to check, we're done */
if (!skb_is_gso(skb) || !skb_shinfo(skb)->nr_frags)
return ndescs;
}
/* We need to scan the skb to be sure that none of the MTU sized
* packets in the TSO will require more sgs per descriptor than we
@ -1743,6 +1746,8 @@ static int ionic_tx_descs_needed(struct ionic_queue *q, struct sk_buff *skb)
linearize:
if (too_many_frags) {
struct ionic_tx_stats *stats = q_to_tx_stats(q);
err = skb_linearize(skb);
if (err)
return err;