From edeaeac8e8580a76e5adcaaae420cd0f24191443 Mon Sep 17 00:00:00 2001 From: Thomas Scheiblauer <tom@sharkbay.at> Date: Thu, 17 Oct 2013 13:14:43 -0500 Subject: [PATCH] imx6q: work around fec tx-queue timeouts when SATA/SD + ethernet is active with high throughput When data is transferred from SATA or is SD-card tx-queue timeouts occur on the ethernet leading to network bandwidth drops to zero every few seconds lasting for about 2-3 seconds (NETDEV WATCHDOG timeout?). This issue gets more apparent the higher the throughput on on all of the mentioned data channels becomes. To reproduce it ethernet throughput should be beyond 40MB/s and SATA or SD at least 35MB/s. Below these values the problem may not be experienced. According to Duan Fugang-B38611 <B38611 <at> freescale.com> it is an SMP related problem that does not appear to happen when running on only one CPU. His proposed work around (fix?) was to increase TX_RING_SIZE in drivers/net/ethernet/freescale/fec.h to 64. In my tests this helped a lot though it didn't completely remedy the issue. I was now able to run at least a couple of minutes with high throughput not having tx-queue timeouts but they still happened now and then. I'm submitting this patch based on Duan Fugang's findings for review and possible further improvement since it doesn't seem like this issue will be explored further by the Freescale(?) people judging by Duan Fugang's most recent email he sent to me and I'm not sure which further consequences the TX_RING_SIZE change will have (increased network latency?). Signed-off-by: Thomas Scheiblauer <tom@sharkbay.at> Signed-off-by: Robert Nelson <robertcnelson@gmail.com> --- drivers/net/ethernet/freescale/fec.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h index 0120217..ee9a1da 100644 --- a/drivers/net/ethernet/freescale/fec.h +++ b/drivers/net/ethernet/freescale/fec.h @@ -246,7 +246,7 @@ struct bufdesc_ex { #define RX_RING_SIZE (FEC_ENET_RX_FRPPG * FEC_ENET_RX_PAGES) #define FEC_ENET_TX_FRSIZE 2048 #define FEC_ENET_TX_FRPPG (PAGE_SIZE / FEC_ENET_TX_FRSIZE) -#define TX_RING_SIZE 16 /* Must be power of two */ +#define TX_RING_SIZE 64 /* Must be power of two */ #define TX_RING_MOD_MASK 15 /* for this to work */ #define BD_ENET_RX_INT 0x00800000 -- 1.8.4.rc3