Date: Wed, 21 Aug 2002 07:51:45 -0700 From: Luigi Rizzo <rizzo@icir.org> To: Andre Song <song@rdsk.net> Cc: freebsd-net@FreeBSD.ORG Subject: fxp performance (was Re: m_getcl and end-to-end performance) Message-ID: <20020821075145.B57063@iguana.icir.org> In-Reply-To: <3D63A3C2.26A938D4@rdsk.net>; from song@rdsk.net on Wed, Aug 21, 2002 at 10:29:22PM %2B0800 References: <15714.27671.533860.408996@grasshopper.cs.duke.edu> <20020820093939.B48541@iguana.icir.org> <15714.39494.661931.882244@grasshopper.cs.duke.edu> <20020820132957.B49141@iguana.icir.org> <15714.43504.493596.791872@grasshopper.cs.duke.edu> <20020820135736.A50369@iguana.icir.org> <3D63A3C2.26A938D4@rdsk.net>
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On Wed, Aug 21, 2002 at 10:29:22PM +0800, Andre Song wrote:
> Hi, Luigi
>
> Do you have any plan to publish these improvments (extended and
> simplified
> TxCB)? I'm very interesting in them.
excended TxCB are already used by the driver in -current and -stable, if
they are available on the hardware (apparently old chip revisions do
not support them).
The "simplified TxCB" is really just a trick to look good in benchmarks,
but i do not plan to commit it -- it is just ugly and in the end
it does not really help much, because the hardware seems unable to
reach line speed anyways (and no, i am not running out of cpu, an
"em" card on the same machine can push out almost 650kpps).
Anyways, the code below should do -- you can enable/disable it at
runtime with
sysctl hw.fxp_tx_copy=1
cheers
luigi
> Regards,
> song
>
> Luigi Rizzo wrote:
> >
>
> > which gets you close to the max throughput for the chip (not the driver!)
> > used by the "fxp" driver, which is:
> >
> > 103kpps with standard TxCB
> > 113kpps with extended TxCB
> > 127kpps if you know the above problem, so do not use buffer
> > descriptors and copy (small) packets into the TxCB
> >
> > don't ask me why, i have no docs and no idea
--- if_fxp.c Sun Aug 11 11:25:43 2002
+++ if_fxp.c.fast Fri Aug 9 03:50:47 2002
@@ -97,6 +97,9 @@
* (1536 bytes), if an underrun occurs.
*/
static int tx_threshold = 64;
+static int tx_copy;
+SYSCTL_INT(_hw, OID_AUTO, fxp_tx_copy, CTLFLAG_RW,
+ &tx_copy, 0, "fxp copy small bufs");
/*
* The configuration byte map has several undefined fields which
@@ -1046,6 +1051,22 @@
* the transmit buffer descriptors with the physical address
* and size of the mbuf.
*/
+#if 1
+ /*
+ * if it is small, use simple mode and put everything in
+ * the TxCB
+ */
+ if (tx_copy && mb_head->m_next == NULL && mb_head->m_len < 128) {
+ int i = sc->flags & FXP_FLAG_EXT_TXCB ? 2 : 0;
+
+ bcopy(mtod(mb_head, char *),
+ (char *)&(txp->tbd[i]), mb_head->m_len);
+ txp->byte_count = mb_head->m_len;
+ segment = 0;
+ txp->tbd_array_addr = 0xffffffff;
+ goto got_it;
+ }
+#endif
tbdinit:
for (m = mb_head, segment = 0; m != NULL; m = m->m_next) {
if (m->m_len != 0) {
@@ -1086,16 +1107,24 @@
goto tbdinit;
}
+ if (sc->flags & FXP_FLAG_EXT_TXCB)
+ txp->tbd_array_addr = vtophys(&txp->tbd[2]);
+ else
+ txp->tbd_array_addr = vtophys(&txp->tbd[0]);
+ txp->byte_count = 0;
+got_it:
txp->tbd_number = segment;
txp->mb_head = mb_head;
txp->cb_status = 0;
if (sc->tx_queued != FXP_CXINT_THRESH - 1) {
txp->cb_command =
- FXP_CB_COMMAND_XMIT | FXP_CB_COMMAND_SF |
+ FXP_CB_COMMAND_XMIT |
+ (segment ? FXP_CB_COMMAND_SF:0) |
FXP_CB_COMMAND_S;
} else {
txp->cb_command =
- FXP_CB_COMMAND_XMIT | FXP_CB_COMMAND_SF |
+ FXP_CB_COMMAND_XMIT |
+ (segment ? FXP_CB_COMMAND_SF:0) |
FXP_CB_COMMAND_S | FXP_CB_COMMAND_I;
/*
* Set a 5 second timer just in case we don't hear
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