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Code Issues Releases Activity

- Use m_collapse(9) instead of m_defrag(9) if possible. This results

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in a noticeable reduction in system time spent.
- If bus_dmamap_load_mbuf_sg(9) fails with EFBIG and we already have
  defragmented the mbuf chain, don't bother to defragment and load it
  a second time just yet as it's likely to fail again anyway.

MFC after:	3 days
This commit is contained in:
Marius Strobl 2008-08-23 20:57:48 +00:00
parent 6adb632eeb
commit 993a741ac6
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=182079
1 changed files with 27 additions and 18 deletions
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45
sys/dev/dc/if_dc.c
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@ -3138,7 +3138,7 @@ dc_encap(struct dc_softc *sc, struct mbuf **m_head)
bus_dma_segment_t segs[DC_MAXFRAGS];
struct dc_desc *f;
struct mbuf *m;
int chainlen, cur, error, first, frag, i, idx, nseg;
int cur, defragged, error, first, frag, i, idx, nseg;
/*
* If there's no way we can send any packets, return now.
@ -3146,22 +3146,30 @@ dc_encap(struct dc_softc *sc, struct mbuf **m_head)
if (DC_TX_LIST_CNT - sc->dc_cdata.dc_tx_cnt <= DC_TX_LIST_RSVD)
return (ENOBUFS);
/*
* Count the number of frags in this chain to see if
* we need to m_defrag. Since the descriptor list is shared
* by all packets, we'll m_defrag long chains so that they
* do not use up the entire list, even if they would fit.
*/
chainlen = 0;
for (m = *m_head; m != NULL; m = m->m_next)
chainlen++;
m = NULL;
if ((sc->dc_flags & DC_TX_COALESCE && ((*m_head)->m_next != NULL ||
sc->dc_flags & DC_TX_ALIGN)) || (chainlen > DC_TX_LIST_CNT / 4) ||
(DC_TX_LIST_CNT - (chainlen + sc->dc_cdata.dc_tx_cnt) <=
DC_TX_LIST_RSVD)) {
defragged = 0;
if (sc->dc_flags & DC_TX_COALESCE &&
((*m_head)->m_next != NULL || sc->dc_flags & DC_TX_ALIGN)) {
m = m_defrag(*m_head, M_DONTWAIT);
defragged = 1;
} else {
/*
* Count the number of frags in this chain to see if we
* need to m_collapse. Since the descriptor list is shared
* by all packets, we'll m_collapse long chains so that they
* do not use up the entire list, even if they would fit.
*/
i = 0;
for (m = *m_head; m != NULL; m = m->m_next)
i++;
if (i > DC_TX_LIST_CNT / 4 ||
DC_TX_LIST_CNT - i + sc->dc_cdata.dc_tx_cnt <=
DC_TX_LIST_RSVD) {
m = m_collapse(*m_head, M_DONTWAIT, DC_MAXFRAGS);
defragged = 1;
}
}
if (defragged != 0) {
if (m == NULL) {
m_freem(*m_head);
*m_head = NULL;
@ -3169,15 +3177,16 @@ dc_encap(struct dc_softc *sc, struct mbuf **m_head)
}
*m_head = m;
}
idx = sc->dc_cdata.dc_tx_prod;
error = bus_dmamap_load_mbuf_sg(sc->dc_mtag,
sc->dc_cdata.dc_tx_map[idx], *m_head, segs, &nseg, 0);
if (error == EFBIG) {
m = m_defrag(*m_head, M_DONTWAIT);
if (m == NULL) {
if (defragged != 0 || (m = m_collapse(*m_head, M_DONTWAIT,
DC_MAXFRAGS)) == NULL) {
m_freem(*m_head);
*m_head = NULL;
return (ENOBUFS);
return (defragged != 0 ? error : ENOBUFS);
}
*m_head = m;
error = bus_dmamap_load_mbuf_sg(sc->dc_mtag,