Re: b44: regression in 2.6.22 (resend)

Maximilian Engelhardt
2007-05-27T22:16:35Z

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On Sunday 27 May 2007, Michael Buesch wrote:
> On Sunday 27 May 2007 21:25:17 Maximilian Engelhardt wrote:
> > 2.6.21.1:
> > [ 5] local 192.168.1.2 port 58414 connected with 192.168.1.1 port 5001
> > [ 5] 0.0-60.6 sec 1.13 MBytes 157 Kbits/sec
> > [ 4] local 192.168.1.2 port 5001 connected with 192.168.1.1 port 57837
> > [ 4] 0.0-63.1 sec 2.82 MBytes 375 Kbits/sec
> >
> > 2.6.22-rc3:
> > [ 5] local 192.168.1.2 port 46557 connected with 192.168.1.1 port 5001
> > [ 5] 0.0-60.4 sec 58.9 MBytes 8.18 Mbits/sec
> > [ 4] local 192.168.1.2 port 5001 connected with 192.168.1.1 port 51633
> > [ 4] 0.0-63.1 sec 7.27 MBytes 967 Kbits/sec
>
> This is the diff between these two kernels.
> I'm not sure why you see a much better TX throughput here.
>
> Can you re-check to make sure it's not just some test-jitter?
>
2.6.21.1:

[ 5] local 192.168.1.2 port 54423 connected with 192.168.1.1 port 5001
[ 5] 0.0-60.3 sec 3.06 MBytes 426 Kbits/sec
[ 4] local 192.168.1.2 port 5001 connected with 192.168.1.1 port 41053
[ 4] 0.0-163.0 sec 130 MBytes 6.67 Mbits/sec

2.6.22-rc3:

[ 5] local 192.168.1.2 port 46002 connected with 192.168.1.1 port 5001
[ 5] 0.0-61.5 sec 84.0 MBytes 11.5 Mbits/sec
[ 4] local 192.168.1.2 port 5001 connected with 192.168.1.1 port 44379
[ 4] 0.0-93.8 sec 30.6 MBytes 2.74 Mbits/sec

For TX the iperf server reports the same values as the client (all values are
from the client) but for RX they are differen:

2.6.21.1: (iperf server log):

[ 5] local 192.168.1.1 port 5001 connected with 192.168.1.2 port 54423
[ 5] 0.0-60.5 sec 3.06 MBytes 425 Kbits/sec
[ 5] local 192.168.1.1 port 41053 connected with 192.168.1.2 port 5001
[ 5] 0.0-63.1 sec 130 MBytes 17.2 Mbits/sec

2.6.22-rc3 (iperf server log):

[ 4] local 192.168.1.1 port 5001 connected with 192.168.1.2 port 46002
[ 4] 0.0-61.6 sec 84.0 MBytes 11.5 Mbits/sec
[ 4] local 192.168.1.1 port 44379 connected with 192.168.1.2 port 5001
[ 4] 0.0-63.3 sec 30.6 MBytes 4.06 Mbits/sec

I have no idea how iperf internally works and what can cause such different
results here.

>
> --- linux-2.6.21.1/drivers/net/b44.c 2007-05-27 22:58:01.000000000 +0200
> +++ linux-2.6.22-rc3/drivers/net/b44.c 2007-05-27 23:01:44.000000000 +0200
> @@ -825,12 +825,11 @@
> if (copy_skb == NULL)
> goto drop_it_no_recycle;
>
> - copy_skb->dev = bp->dev;
> skb_reserve(copy_skb, 2);
> skb_put(copy_skb, len);
> /* DMA sync done above, copy just the actual packet
> */ - memcpy(copy_skb->data, skb->data+bp->rx_offset,
> len); -
> + skb_copy_from_linear_data_offset(skb,
> bp->rx_offset, +
> copy_skb->data, len); skb = copy_skb;
> }
> skb->ip_summed = CHECKSUM_NONE;
> @@ -1007,7 +1006,8 @@
> goto err_out;
> }
>
> - memcpy(skb_put(bounce_skb, len), skb->data, skb->len);
> + skb_copy_from_linear_data(skb, skb_put(bounce_skb, len),
> + skb->len);
> dev_kfree_skb_any(skb);
> skb = bounce_skb;
> }

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