Jan Kiszka wrote: > Jan Kiszka wrote: >> Lauener Nathan wrote: >>> Our adminstrators have obviously changed our email address. Here is the >>> posting once more, from a new address. Sorry, if anyone should receive >>> it twice. >>> >>> --------- >>> >>> Hi, >>> >>> after switching to a new linux box I now have high latency on >>> rt_dev_recvmsg(). Instead of approximately 20us I now measure up to 1ms! >>> I use the same network card which uses the rt_natsemi driver. The >>> software is the same, only compiled it on the new box. The >>> Ethernet-package sent by the controller is immediately sent back by the >>> receiver. The response time according to our network sniffer is about 10 >>> us, so there should be something to read. Introducing a sleep of 100us >>> before reading didn't help. I also have debug symbols in the kernel log, >>> looks like a trace. Maybe the logging causes the latency, but I could >>> not turn the logging off, no matter what options or versions of the >>> kernel, xenomai or rtnet that I tried. Here is a short printout of the >>> log. >> The latency might be related to the BUG printing. The BUG itself is >> already a problem that demands to be looked at. > > Looks like a bug of rt_natsemi (dma mapping of rx buffers with wrong > size). Will come up with a patch soon. >
Here we go: please try attached patch or, alternatively, SVN head. Should solve it. Thanks for reporting, Jan
Index: drivers/rt_natsemi.c
===================================================================
--- drivers/rt_natsemi.c (revision 1050)
+++ drivers/rt_natsemi.c (working copy)
@@ -1556,7 +1556,7 @@ static void refill_rx(struct rtnet_devic
break; /* Better luck next round. */
skb->rtdev = dev; /* Mark as being used by this device.
*/
np->rx_dma[entry] = pci_map_single(np->pci_dev,
- skb->data, skb->len, PCI_DMA_FROMDEVICE);
+ skb->data, np->rx_buf_sz, PCI_DMA_FROMDEVICE);
np->rx_ring[entry].addr =
cpu_to_le32(np->rx_dma[entry]);
}
np->rx_ring[entry].cmd_status = cpu_to_le32(np->rx_buf_sz);
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