Currently udp sender my send whenever it has data and if it does
this faster than packets can be transmitted we will run out of memory.
This patch limits how much outstanding data each native udp channel may
have.
L4 will provide the callback to be called by L3 after the packet is
handled to lower layers for transmission. L4 will know that it can queue
more data from user at this point. The patch also change send function
that can no longer block to return void instead of future<>.
The current shared_ptr implementation is efficient, but does not support
polymorphic types.
Rename it in order to make room for a polymorphic shared_ptr.
Instead of forward() deciding packet destination make it collect input
for RSS hash function depending on packet type. After data is collected
use toeplitz hash function to calculate packet's destination.
This patch uses the NIC's capability to calculate in hardware the IP, TCP
and UDP checksums on outgoing packets, instead of us doing this on the
sending CPU. This can save us quite a bit of calculations (especially for
the TCP/UDP checksum of full-sized packets), and avoid cache-polution on
the CPU when sending cold data.
On my setup this patch improves the performance of a single-cpu memcached
by 6%. Together with the recent patch for receive-side checksum offloading,
the total improvement is 10%.
This patch is somewhat complicated by the fact we have so many different
combinations of checksum-offloading capabilities; While virtio can only
offload layer-4 checksumming (tcp/udp), dpdk lets us offload both ip and
layer-4 checksum. Moreover, some packets are just IP but not TCP/UDP
(e.g., ICMP), and some packets are not even IP (e.g., ARP), so this
patch modifies a few of the hardware-features flags and the per-packet
offload-information flags to fit our new needs.
Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Some packets, like arp replies, are broadcast to all cpus for handling,
but only packet structure is copied for each cpu, the actual packet data
is the same for all of them. Currently networking stack mangles a
packet data during its travel up the stack while doing ntoh()
translations which cannot obviously work for broadcaster packets. This
patches fixes the code to not modify packet data while doing ntoh(), but
do it in a stack allocated copy of a data instead.
It's too easy to shoot yourself in the foot when trying to call
get_src() after packet data was moved.
Reported-by: Asias He <asias@cloudius-systems.com>
Classifier returns what cpu a packets should be processed on. It may
return special broadcast identifier. The patch includes classifier for
tcp, udp and arp. Arp classifier broadcasts arp reply to all cpus. Default
classifier does not forward packet.
