Author: np
Date: Sat Mar 5 03:54:37 2011
New Revision: 219292
URL: http://svn.freebsd.org/changeset/base/219292
Log:
Calculate how many descriptors can be reclaimed before calling
reclaim_tx_descs
Modified:
head/sys/dev/cxgbe/t4_sge.c
Modified: head/sys/dev/cxgbe/t4_sge.c
==============================================================================
--- head/sys/dev/cxgbe/t4_sge.c Sat Mar 5 03:46:24 2011 (r219291)
+++ head/sys/dev/cxgbe/t4_sge.c Sat Mar 5 03:54:37 2011 (r219292)
@@ -135,6 +135,7 @@ static inline void write_ulp_cpl_sgl(str
static int write_sgl_to_txd(struct sge_eq *, struct sgl *, caddr_t *);
static inline void copy_to_txd(struct sge_eq *, caddr_t, caddr_t *, int);
static inline void ring_tx_db(struct adapter *, struct sge_eq *);
+static inline int reclaimable(struct sge_eq *);
static int reclaim_tx_descs(struct sge_eq *, int, int);
static void write_eqflush_wr(struct sge_eq *);
static __be64 get_flit(bus_dma_segment_t *, int, int);
@@ -753,22 +754,21 @@ t4_eth_tx(struct ifnet *ifp, struct sge_
struct sge_eq *eq = &txq->eq;
struct buf_ring *br = eq->br;
struct mbuf *next;
- int rc, coalescing;
+ int rc, coalescing, can_reclaim;
struct txpkts txpkts;
struct sgl sgl;
TXQ_LOCK_ASSERT_OWNED(txq);
KASSERT(m, ("%s: called with nothing to do.", __func__));
+ prefetch(&eq->desc[eq->pidx]);
+ prefetch(&eq->sdesc[eq->pidx]);
+
txpkts.npkt = 0;/* indicates there's nothing in txpkts */
coalescing = 0;
- prefetch(&eq->sdesc[eq->pidx]);
- prefetch(&eq->desc[eq->pidx]);
- prefetch(&eq->maps[eq->map_pidx]);
-
if (eq->avail < 8)
- reclaim_tx_descs(eq, 1, 8);
+ reclaim_tx_descs(eq, 0, 8);
for (; m; m = next ? next : drbr_dequeue(ifp, br)) {
@@ -824,7 +824,7 @@ t4_eth_tx(struct ifnet *ifp, struct sge_
coalescing = 0;
if (eq->avail < 8)
- reclaim_tx_descs(eq, 1, 8);
+ reclaim_tx_descs(eq, 0, 8);
rc = write_txpkt_wr(pi, txq, m, &sgl);
if (rc != 0) {
@@ -851,7 +851,10 @@ doorbell:
/* Fewer and fewer doorbells as the queue fills up */
if (eq->pending >= (1 << (fls(eq->qsize - eq->avail) / 2)))
ring_tx_db(sc, eq);
- reclaim_tx_descs(eq, 16, 32);
+
+ can_reclaim = reclaimable(eq);
+ if (can_reclaim >= 32)
+ reclaim_tx_descs(eq, can_reclaim, 32);
}
if (txpkts.npkt > 0)
@@ -874,7 +877,9 @@ doorbell:
if (eq->pending)
ring_tx_db(sc, eq);
- reclaim_tx_descs(eq, 16, eq->qsize);
+ can_reclaim = reclaimable(eq);
+ if (can_reclaim >= 32)
+ reclaim_tx_descs(eq, can_reclaim, 128);
return (0);
}
@@ -2271,32 +2276,40 @@ ring_tx_db(struct adapter *sc, struct sg
eq->pending = 0;
}
-static int
-reclaim_tx_descs(struct sge_eq *eq, int atleast, int howmany)
+static inline int
+reclaimable(struct sge_eq *eq)
{
- struct tx_sdesc *txsd;
- struct tx_map *txm, *next_txm;
- unsigned int cidx, can_reclaim, reclaimed, maps, next_map_cidx;
-
- EQ_LOCK_ASSERT_OWNED(eq);
+ unsigned int cidx;
cidx = eq->spg->cidx; /* stable snapshot */
cidx = be16_to_cpu(cidx);
if (cidx >= eq->cidx)
- can_reclaim = cidx - eq->cidx;
+ return (cidx - eq->cidx);
else
- can_reclaim = cidx + eq->cap - eq->cidx;
+ return (cidx + eq->cap - eq->cidx);
+}
+
+/*
+ * There are "can_reclaim" tx descriptors ready to be reclaimed. Reclaim as
+ * many as possible but stop when there are around "n" mbufs to free.
+ *
+ * The actual number reclaimed is provided as the return value.
+ */
+static int
+reclaim_tx_descs(struct sge_eq *eq, int can_reclaim, int n)
+{
+ struct tx_sdesc *txsd;
+ struct tx_map *txm;
+ unsigned int reclaimed, maps;
- if (can_reclaim < atleast)
- return (0);
+ EQ_LOCK_ASSERT_OWNED(eq);
- next_map_cidx = eq->map_cidx;
- next_txm = txm = &eq->maps[next_map_cidx];
- prefetch(txm);
+ if (can_reclaim == 0)
+ can_reclaim = reclaimable(eq);
maps = reclaimed = 0;
- do {
+ while (can_reclaim && maps < n) {
int ndesc;
txsd = &eq->sdesc[eq->cidx];
@@ -2308,15 +2321,18 @@ reclaim_tx_descs(struct sge_eq *eq, int
__func__, can_reclaim, ndesc));
maps += txsd->map_used;
+
reclaimed += ndesc;
+ can_reclaim -= ndesc;
eq->cidx += ndesc;
- if (eq->cidx >= eq->cap)
+ if (__predict_false(eq->cidx >= eq->cap))
eq->cidx -= eq->cap;
+ }
- can_reclaim -= ndesc;
-
- } while (can_reclaim && reclaimed < howmany);
+ txm = &eq->maps[eq->map_cidx];
+ if (maps)
+ prefetch(txm->m);
eq->avail += reclaimed;
KASSERT(eq->avail < eq->cap, /* avail tops out at (cap - 1) */
@@ -2326,22 +2342,22 @@ reclaim_tx_descs(struct sge_eq *eq, int
KASSERT(eq->map_avail <= eq->map_total,
("%s: too many maps available", __func__));
- prefetch(txm->m);
while (maps--) {
- next_txm++;
- if (++next_map_cidx == eq->map_total) {
- next_map_cidx = 0;
- next_txm = eq->maps;
- }
- prefetch(next_txm->m);
+ struct tx_map *next;
+
+ next = txm + 1;
+ if (__predict_false(eq->map_cidx + 1 == eq->map_total))
+ next = eq->maps;
+ prefetch(next->m);
bus_dmamap_unload(eq->tx_tag, txm->map);
m_freem(txm->m);
txm->m = NULL;
- txm = next_txm;
+ txm = next;
+ if (__predict_false(++eq->map_cidx == eq->map_total))
+ eq->map_cidx = 0;
}
- eq->map_cidx = next_map_cidx;
return (reclaimed);
}
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