* [PATCH] work around 5701 misalignment
@ 2004-10-13 20:54 Jesse Barnes
2004-10-13 20:57 ` Jeff Garzik
0 siblings, 1 reply; 3+ messages in thread
From: Jesse Barnes @ 2004-10-13 20:54 UTC (permalink / raw)
To: jgarzik, netdev
[-- Attachment #1: Type: text/plain, Size: 367 bytes --]
This patch helps deal with 5701s running in PCI-X mode on platforms (like
ia64) where unaligned accesses are very expensive. It was made a config
option at davem's request, afaik, and only affects 5701s when enabled. Patch
originally by John Partridge.
Signed-off-by: Jesse Barnes <jbarnes@sgi.com>
Signed-off-by: John Partridge <johnip@sgi.com>
Thanks,
Jesse
[-- Attachment #2: tg3-unaligned-expensive.patch --]
[-- Type: text/x-diff, Size: 1328 bytes --]
===========================================================================
linux/drivers/net/Kconfig
===========================================================================
--- a/linux/drivers/net/Kconfig 2004-10-13 15:25:03.000000000 -0500
+++ b/linux/drivers/net/Kconfig 2004-10-13 15:22:39.000000000 -0500
@@ -2062,6 +2062,15 @@
endmenu
+config UNALIGNED_EXPENSIVE
+ depends on TIGON3
+ bool "Do aligned kernel buffers for PCI-X 5701 Cards"
+ help
+ This aligns kernel buffers for PCI-X 5701
+ other cards do not have this problem.
+ This will help performance on 5701 cards
+ and not adversly affect any other cards.
+
#
# 10 Gigabit Ethernet
#
===========================================================================
linux/drivers/net/tg3.c
===========================================================================
--- a/linux/drivers/net/tg3.c 2004-10-13 15:25:03.000000000 -0500
+++ b/linux/drivers/net/tg3.c 2004-10-13 15:14:45.000000000 -0500
@@ -2352,7 +2352,12 @@
len = ((desc->idx_len & RXD_LEN_MASK) >> RXD_LEN_SHIFT) - 4; /* omit crc */
- if (len > RX_COPY_THRESHOLD) {
+ if (len > RX_COPY_THRESHOLD
+#if defined(CONFIG_UNALIGNED_EXPENSIVE)
+ && tp->rx_offset == 2
+#endif
+)
+{
int skb_size;
skb_size = tg3_alloc_rx_skb(tp, opaque_key,
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] work around 5701 misalignment
2004-10-13 20:54 [PATCH] work around 5701 misalignment Jesse Barnes
@ 2004-10-13 20:57 ` Jeff Garzik
2004-10-20 6:15 ` David S. Miller
0 siblings, 1 reply; 3+ messages in thread
From: Jeff Garzik @ 2004-10-13 20:57 UTC (permalink / raw)
To: Jesse Barnes; +Cc: netdev, David S. Miller
Jesse Barnes wrote:
> --- a/linux/drivers/net/tg3.c 2004-10-13 15:25:03.000000000 -0500
> +++ b/linux/drivers/net/tg3.c 2004-10-13 15:14:45.000000000 -0500
> @@ -2352,7 +2352,12 @@
>
> len = ((desc->idx_len & RXD_LEN_MASK) >> RXD_LEN_SHIFT) - 4; /* omit crc */
>
> - if (len > RX_COPY_THRESHOLD) {
> + if (len > RX_COPY_THRESHOLD
> +#if defined(CONFIG_UNALIGNED_EXPENSIVE)
> + && tp->rx_offset == 2
> +#endif
hmmm, the normal solution is to give RX_COPY_THRESHOLD a per-arch value.
Grep for 'rx_copybreak' in bunches of net drivers.
DaveM might squirm a bit but IMHO RX_COPY_THRESHOLD really is
platform-dependent.
Jeff
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] work around 5701 misalignment
2004-10-13 20:57 ` Jeff Garzik
@ 2004-10-20 6:15 ` David S. Miller
0 siblings, 0 replies; 3+ messages in thread
From: David S. Miller @ 2004-10-20 6:15 UTC (permalink / raw)
To: Jeff Garzik; +Cc: jbarnes, netdev, davem
On Wed, 13 Oct 2004 16:57:28 -0400
Jeff Garzik <jgarzik@pobox.com> wrote:
> DaveM might squirm a bit but IMHO RX_COPY_THRESHOLD really is
> platform-dependent.
I'm not totally against such an idea.
We have something similar already in the form
of NET_IP_ALIGN which ppc64 overrides.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2004-10-13 20:54 [PATCH] work around 5701 misalignment Jesse Barnes
2004-10-13 20:57 ` Jeff Garzik
2004-10-20 6:15 ` David S. Miller
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