On Tue, 2013-10-15 at 16:15 +0200, Sébastien Dugué wrote:
> Hi Eric,
>
> On Tue, 15 Oct 2013 07:06:25 -0700
> Eric Dumazet <eric.duma...@gmail.com> wrote:
> > But the csum cost is both for sender and receiver ?
>
> No, it was only on the receiver side that I noticed it.
>
Yes, as Andi said, we do the csum while copying the data for the
sender : (I disabled hardware assist tx checksum using 'ethtool -K eth0
tx off')
17.21% netperf [kernel.kallsyms] [k]
csum_partial_copy_generic
|
--- csum_partial_copy_generic
|
|--97.39%-- __libc_send
|
--2.61%-- tcp_sendmsg
inet_sendmsg
sock_sendmsg
_sys_sendto
sys_sendto
system_call_fastpath
__libc_send
> Sorry, but this is 3 years old stuff and I do not have the
> setup anymore to reproduce.
And the receiver should also do the same : (ethtool -K eth0 rx off)
10.55% netserver [kernel.kallsyms] [k]
csum_partial_copy_generic
|
--- csum_partial_copy_generic
|
|--98.24%-- __libc_recv
|
--1.76%-- skb_copy_and_csum_datagram
skb_copy_and_csum_datagram_iovec
tcp_rcv_established
tcp_v4_do_rcv
|
|--73.05%-- tcp_prequeue_process
| tcp_recvmsg
| inet_recvmsg
| sock_recvmsg
| SYSC_recvfrom
| SyS_recvfrom
| system_call_fastpath
| __libc_recv
|
So I suspect something is wrong with IPoIB.
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