On 05/27/13 at 10:28am, Jesse Gross wrote:
> On Saturday, May 25, 2013, Eric Dumazet wrote:
>
> > On Sat, 2013-05-25 at 08:02 +0100, Thomas Graf wrote:
> >
> > > I ran TCP_CRR to verify the SYN/ACK use case and I did not
> > > observe a difference. If you have any specific test in mind
> > > I will be glad to run that before posting the 2nd revision.
> >
> > I guess you should test with rx checksum disabled as well, Jesse seemed
> > to be concerned about that.
>
>
> I was actually thinking about the transmit side - rx checksum verification
> doesn't matter much here since the result will get thrown away. However, if
> the packet is CHECKSUM_PARTIAL then the checksum will have to get filled in
> first and that's the code path that is a little different now.
Do we actually need to complete the checksum before doing the
upcall and if so, why? Couldn't the slow path do that if needed?
The only reason I can think of where it would matter is if a
controller injects the packet into another network stack such
as RouteFlow.
On the receive side, hitting an ovs bridge connected to two
interface with ~18G of randomized flows:
3.10.0-rc2+:
+ 9.44% ksoftirqd/0 [k] csum_partial_copy_generic
+ 3.54% ovs-vswitchd [k] copy_user_enhanced_fast_string
+ 3.08% swapper [k] intel_idle
+ 2.47% ksoftirqd/0 [k] memset
+ 2.21% ksoftirqd/0 [k] memcpy
+ 1.64% ksoftirqd/0 [k] __nla_reserve
+ 1.26% ovs-vswitchd [k] netlink_recvmsg
+ 1.07% ksoftirqd/0 [k] __netif_receive_skb_core
+ 1.02% ksoftirqd/0 [k] __pskb_pull_tail
+ 0.98% swapper [k] csum_partial_copy_generic
+ 0.95% ovs-vswitchd [k] _raw_spin_lock
+ 0.94% ovs-vswitchd [k] _raw_spin_lock_irqsave
+ 0.83% ovs-vswitchd [k] memcpy
+ 0.80% ksoftirqd/0 [k] __alloc_skb
+ 0.78% ksoftirqd/0 [k] skb_copy_bits
+ 0.71% swapper [k] menu_select
+ 0.71% ksoftirqd/2 [k] csum_partial_copy_generic
3.10.0-rc2+ + zerocopy
+ 4.84% ovs-vswitchd [k] copy_user_enhanced_fast_string
+ 4.74% swapper [k] intel_idle
+ 3.14% swapper [k] memset
+ 3.04% swapper [k] memcpy
+ 2.10% swapper [k] __nla_reserve
+ 1.44% swapper [k] skb_copy_bits
+ 1.40% swapper [k] __netif_receive_skb_core
+ 1.34% swapper [k] __pskb_pull_tail
+ 1.23% ovs-vswitchd [k] _raw_spin_lock
+ 1.16% ovs-vswitchd [k] fib_table_lookup
+ 1.16% swapper [k] irq_entries_start
+ 1.09% ovs-vswitchd [k] memcpy
+ 1.05% swapper [k] __alloc_skb
+ 1.03% swapper [k] lapic_next_deadline
+ 1.02% swapper [k] build_skb
+ 0.99% swapper [k] skb_zerocopy
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