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- no need to set the TXCMD_TXINT bit against the last enqueued TX packet 

because TX_EMPTY interrupt is enough to serve it on TX completion
- start TX right after each TX packet has been prepared

A quick ttcp(1) test shows ~5% improvements.
This commit is contained in:
tsutsui 2008-08-10 18:43:55 +00:00
parent ac5c3a5a8a
commit 8eb2877b11
1 changed files with 5 additions and 14 deletions
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19
sys/arch/sgimips/mace/if_mec.c
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@ -1,4 +1,4 @@
/* $NetBSD: if_mec.c,v 1.24 2008/08/10 16:21:28 tsutsui Exp $ */
/* $NetBSD: if_mec.c,v 1.25 2008/08/10 18:43:55 tsutsui Exp $ */
/*-
* Copyright (c) 2004 Izumi Tsutsui. All rights reserved.
@ -61,7 +61,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if_mec.c,v 1.24 2008/08/10 16:21:28 tsutsui Exp $");
__KERNEL_RCSID(0, "$NetBSD: if_mec.c,v 1.25 2008/08/10 18:43:55 tsutsui Exp $");
#include "opt_ddb.h"
#include "bpfilter.h"
@ -1046,6 +1046,9 @@ mec_start(struct ifnet *ifp)
MEC_TXDESCSYNC(sc, nexttx,
BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);
/* start TX */
bus_space_write_8(st, sh, MEC_TX_RING_PTR, MEC_NEXTTX(nexttx));
/* advance the TX pointer. */
sc->sc_txpending++;
sc->sc_txlast = nexttx;
@ -1057,18 +1060,6 @@ mec_start(struct ifnet *ifp)
}
if (sc->sc_txpending != opending) {
/*
* Cause a TX interrupt to happen on the last packet
* we enqueued.
*/
sc->sc_txdesc[sc->sc_txlast].txd_cmd |= MEC_TXCMD_TXINT;
MEC_TXCMDSYNC(sc, sc->sc_txlast,
BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);
/* start TX */
bus_space_write_8(st, sh, MEC_TX_RING_PTR,
MEC_NEXTTX(sc->sc_txlast));
/*
* If the transmitter was idle,
* reset the txdirty pointer and re-enable TX interrupt.