On 2016/4/12 10:59, Yang Yingliang wrote:
On 2016/4/11 20:13, Eric Dumazet wrote:
On Mon, 2016-04-11 at 19:57 +0800, Yang Yingliang wrote:
On 2016/4/8 22:44, Eric Dumazet wrote:
On Fri, 2016-04-08 at 19:18 +0800, Yang Yingliang wrote:
I expand tcp_adv_win_scale and tcp_rmem. It has no effect.
Try :
echo -2 >/proc/sys/net/ipv4/tcp_adv_win_scale
And restart your flows.
cat /proc/sys/net/ipv4/tcp_rmem
10240 2097152 10485760
What about leaving the default values ?
I tried, it did not work.
$ cat /proc/sys/net/ipv4/tcp_rmem
4096 87380 6291456
echo 102400 20971520 104857600 > /proc/sys/net/ipv4/tcp_rmem
echo -2 >/proc/sys/net/ipv4/tcp_adv_win_scale
It seems has not effect.
I have no idea what you did on the sender side to allow it to send more
than 1.5 MB then.
We are doing performance test. The sender send 256KB per-block with 128
threads to one socket. And the receiver uses 10Gb NIC to handle the
data on ARM64. The data flow is driver->ip layer->tcp layer->iscsi.
I added some debug messages and found handling backlog packets in
__release_sock() cost about 11ms at most. This can cause backlog queue
overflow. The sk_data_ready is re-assigned, it may cost time in our
program. I will check it out.
I traced the cost cycles of handling backlog packets in
__release_sock().
16.97 ms to handling about 12MB backlog packets, of which 13.66ms to do
sk_data_ready.
The speed of handling packets in TCP is 5.65Gb/s which is smaller than
the NIC's bandwidth. So the packets will be dropped.
If the cost of sk_data_read cannot be reduced, do we have other choice
exclude dropping packets ?
