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bcm47xx: revert bgmac back to the old limited max frame size

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Bumping max frame size has significantly affected network performance
and memory usage. It was done by upstream commit that first appeared in
the 5.7 release.

Allocating 512 (BGMAC_RX_RING_SLOTS) buffers, 10 k each, is clearly a
bad idea on 32 MiB devices. This commit fixes support for Linksys E1000
V2.1 which gives up after allocating ~346 such buffers running 5.15
kernel.

Ref: 230c9da963 ("bcm53xx: revert bgmac back to the old limited max frame size")
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
(cherry picked from commit 4970dd027b)
This commit is contained in:
Rafał Miłecki 2023-02-07 18:09:40 +01:00
parent 80a6b0a917
commit e17f9fd0e8
1 changed files with 33 additions and 0 deletions
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33
target/linux/bcm47xx/patches-5.10/701-net-bgmac-connect-to-PHY-even-if-it-is-BGMAC_PHY_NOR.patch Normal file
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@ -0,0 +1,33 @@
From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
Date: Fri, 10 Jun 2022 13:10:47 +0200
Subject: [PATCH] bgmac: reduce max frame size to support just MTU 1500
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
bgmac allocates new replacement buffer before handling each received
frame. Allocating & DMA-preparing 9724 B each time consumes a lot of CPU
time. Ideally bgmac should just respect currently set MTU but it isn't
the case right now. For now just revert back to the old limited frame
size.
This change bumps NAT masquarade speed by ~95%.
Ref: 8c7da63978f1 ("bgmac: configure MTU and add support for frames beyond 8192 byte size")
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
drivers/net/ethernet/broadcom/bgmac.h | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/drivers/net/ethernet/broadcom/bgmac.h
+++ b/drivers/net/ethernet/broadcom/bgmac.h
@@ -366,8 +366,7 @@
#define BGMAC_RX_FRAME_OFFSET 30 /* There are 2 unused bytes between header and real data */
#define BGMAC_RX_BUF_OFFSET (NET_SKB_PAD + NET_IP_ALIGN - \
BGMAC_RX_FRAME_OFFSET)
-/* Jumbo frame size with FCS */
-#define BGMAC_RX_MAX_FRAME_SIZE 9724
+#define BGMAC_RX_MAX_FRAME_SIZE 1536
#define BGMAC_RX_BUF_SIZE (BGMAC_RX_FRAME_OFFSET + BGMAC_RX_MAX_FRAME_SIZE)
#define BGMAC_RX_ALLOC_SIZE (SKB_DATA_ALIGN(BGMAC_RX_BUF_SIZE + BGMAC_RX_BUF_OFFSET) + \
SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))