Module Name: src
Committed By: knakahara
Date: Wed Mar 22 08:44:41 UTC 2017
Modified Files:
src/sys/dev/pci: if_wm.c
Log Message:
add comments about transmit context descriptor
To generate a diff of this commit:
cvs rdiff -u -r1.499 -r1.500 src/sys/dev/pci/if_wm.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/dev/pci/if_wm.c
diff -u src/sys/dev/pci/if_wm.c:1.499 src/sys/dev/pci/if_wm.c:1.500
--- src/sys/dev/pci/if_wm.c:1.499 Wed Mar 22 02:56:12 2017
+++ src/sys/dev/pci/if_wm.c Wed Mar 22 08:44:41 2017
@@ -1,4 +1,4 @@
-/* $NetBSD: if_wm.c,v 1.499 2017/03/22 02:56:12 knakahara Exp $ */
+/* $NetBSD: if_wm.c,v 1.500 2017/03/22 08:44:41 knakahara Exp $ */
/*
* Copyright (c) 2001, 2002, 2003, 2004 Wasabi Systems, Inc.
@@ -84,7 +84,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_wm.c,v 1.499 2017/03/22 02:56:12 knakahara Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_wm.c,v 1.500 2017/03/22 08:44:41 knakahara Exp $");
#ifdef _KERNEL_OPT
#include "opt_net_mpsafe.h"
@@ -6575,6 +6575,13 @@ wm_tx_offload(struct wm_softc *sc, struc
WTX_TCPIP_TUCSE(0) /* rest of packet */;
}
+ /*
+ * We don't have to write context descriptor for every packet
+ * except for 82574. For 82574, we must write context descriptor
+ * for every packet when we use two descriptor queues.
+ * It would be overhead to write context descriptor for every packet,
+ * however it does not cause problems.
+ */
/* Fill in the context descriptor. */
t = (struct livengood_tcpip_ctxdesc *)
&txq->txq_descs[txq->txq_next];
@@ -7176,6 +7183,14 @@ wm_nq_tx_offload(struct wm_softc *sc, st
*fieldsp |= NQTXD_FIELDS_TUXSM;
}
+ /*
+ * We don't have to write context descriptor for every packet to
+ * NEWQUEUE controllers, that is 82575, 82576, 82580, I350, I354,
+ * I210 and I211. It is enough to write once per a Tx queue for these
+ * controllers.
+ * It would be overhead to write context descriptor for every packet,
+ * however it does not cause problems.
+ */
/* Fill in the context descriptor. */
txq->txq_nq_descs[txq->txq_next].nqrx_ctx.nqtxc_vl_len =
htole32(vl_len);
