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Further improve locking in xl(4):

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- Avoid an additional lock acquire/release when leaving xl_intr(), by
   changing xl_start*() to xl_start*_locked(), and calling the appropriate
   routine by chip revision (as the DMA descriptors are different).

 - Simplify the appropriate routines now that they are called with the
   lock held.

This should save a significant amount of CPU cycles spent on servicing
each interrupt for both UP and SMP whilst remaining MPSAFE.

Tested by:	rwatson
This commit is contained in:
bms 2004-07-09 02:28:23 +00:00
parent e828b3b382
commit 44bbb14b5b
1 changed files with 34 additions and 21 deletions
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55
sys/pci/if_xl.c
View File

@ -234,7 +234,9 @@ static void xl_txeof_90xB (struct xl_softc *);
static void xl_txeoc (struct xl_softc *);
static void xl_intr (void *);
static void xl_start (struct ifnet *);
static void xl_start_90xB (struct ifnet *);
static void xl_start_locked (struct ifnet *);
static void xl_start_90xB_locked
(struct ifnet *);
static int xl_ioctl (struct ifnet *, u_long, caddr_t);
static void xl_init (void *);
static void xl_init_locked (struct xl_softc *);
@ -1476,15 +1478,14 @@ xl_attach(device_t dev)
ifp->if_ioctl = xl_ioctl;
ifp->if_capabilities = IFCAP_VLAN_MTU;
if (sc->xl_type == XL_TYPE_905B) {
ifp->if_start = xl_start_90xB;
ifp->if_hwassist = XL905B_CSUM_FEATURES;
#ifdef XL905B_TXCSUM_BROKEN
ifp->if_capabilities |= IFCAP_RXCSUM;
#else
ifp->if_capabilities |= IFCAP_HWCSUM;
#endif
} else
ifp->if_start = xl_start;
}
ifp->if_start = xl_start;
ifp->if_watchdog = xl_watchdog;
ifp->if_init = xl_init;
ifp->if_baudrate = 10000000;
@ -2281,10 +2282,14 @@ xl_intr(void *arg)
}
}
XL_UNLOCK(sc);
if (!IFQ_DRV_IS_EMPTY(&ifp->if_snd)) {
if (sc->xl_type == XL_TYPE_905B)
xl_start_90xB_locked(ifp);
else
xl_start_locked(ifp);
}
if (!IFQ_DRV_IS_EMPTY(&ifp->if_snd))
(*ifp->if_start)(ifp);
XL_UNLOCK(sc);
}
/*
@ -2429,8 +2434,24 @@ xl_encap(struct xl_softc *sc, struct xl_chain *c, struct mbuf *m_head)
* copy of the pointers since the transmit list fragment pointers are
* physical addresses.
*/
static void
xl_start(struct ifnet *ifp)
{
struct xl_softc *sc = ifp->if_softc;
XL_LOCK(sc);
if (sc->xl_type == XL_TYPE_905B)
xl_start_90xB_locked(ifp);
else
xl_start_locked(ifp);
XL_UNLOCK(sc);
}
static void
xl_start_locked(struct ifnet *ifp)
{
struct xl_softc *sc = ifp->if_softc;
struct mbuf *m_head = NULL;
@ -2439,7 +2460,7 @@ xl_start(struct ifnet *ifp)
u_int32_t status;
int error;
XL_LOCK(sc);
XL_LOCK_ASSERT(sc);
/*
* Check for an available queue slot. If there are none,
@ -2450,7 +2471,6 @@ xl_start(struct ifnet *ifp)
xl_txeof(sc);
if (sc->xl_cdata.xl_tx_free == NULL) {
ifp->if_flags |= IFF_OACTIVE;
XL_UNLOCK(sc);
return;
}
}
@ -2493,10 +2513,8 @@ xl_start(struct ifnet *ifp)
/*
* If there are no packets queued, bail.
*/
if (cur_tx == NULL) {
XL_UNLOCK(sc);
if (cur_tx == NULL)
return;
}
/*
* Place the request for the upload interrupt
@ -2557,12 +2575,10 @@ xl_start(struct ifnet *ifp)
* we may as well take advantage of it. :)
*/
xl_rxeof(sc);
XL_UNLOCK(sc);
}
static void
xl_start_90xB(struct ifnet *ifp)
xl_start_90xB_locked(struct ifnet *ifp)
{
struct xl_softc *sc = ifp->if_softc;
struct mbuf *m_head = NULL;
@ -2570,10 +2586,10 @@ xl_start_90xB(struct ifnet *ifp)
struct xl_chain *prev_tx;
int error, idx;
XL_LOCK(sc);
XL_LOCK_ASSERT(sc);
if (ifp->if_flags & IFF_OACTIVE)
goto out_locked;
return;
idx = sc->xl_cdata.xl_tx_prod;
start_tx = &sc->xl_cdata.xl_tx_chain[idx];
@ -2618,7 +2634,7 @@ xl_start_90xB(struct ifnet *ifp)
* If there are no packets queued, bail.
*/
if (cur_tx == NULL)
goto out_locked;
return;
/*
* Place the request for the upload interrupt
@ -2640,9 +2656,6 @@ xl_start_90xB(struct ifnet *ifp)
* Set a timeout in case the chip goes out to lunch.
*/
ifp->if_timer = 5;
out_locked:
XL_UNLOCK(sc);
}
static void