From: Ammar Yasser
This work is based on the original v2 RFC by Eugenio Perez:
Link:
https://archives.passt.top/passt-dev/20250709174748.3514693-1-eperezma@redha...
It is the first finished patch series for vhost-kernel support after a
third RFC was submitted:
Link:
https://archives.passt.top/passt-dev/20260802132155.870796-1-aerosound161@gm...
vhost-net is a kernel device that allows reading and writing packets to a
tap device using virtqueues instead of read(2), write(2), and their
vectored counterparts. Frames are handed over through a shared descriptor
ring, so several of them can be passed to the kernel at once rather than
issuing a syscall per frame.
The changes reliably yield a roughly 2x speedup on the TX path (container
to host).
Numbers were obtained through iperf3 with the following methodology and
results:
Pasta command:
./pasta -f --runas 0:0 --map-guest-addr 192.168.0.5
--vhost-kernel on --config-net 2729785
Host:
iperf3 -s1J
Container:
iperf3 -c 192.168.0.5 -t 10 -P4 -l 1M -w 32M -i1
With --vhost-kernel on:
[SUM] 0.00-10.00 sec 1.36 GBytes 1.17 Gbits/sec 3643 sender
[SUM] 0.00-10.00 sec 1.16 GBytes 999 Mbits/sec receiver
With --vhost-kernel off:
[SUM] 0.00-10.00 sec 700 MBytes 587 Mbits/sec 3556 sender
[SUM] 0.00-10.10 sec 495 MBytes 411 Mbits/sec receiver
v2:
- removed all use of epoll_ctl in vhost_setup_eventfds in favor of epoll_add
- prevent all functions that register memory regions into the vhost_memory
object from overflowing
- remove the unions with flexible array members in vring_avail_pasta and
vring_used_pasta in favor of hardcoding the ring array to have VHOST_NDESCS
entries to avoid having to ignore Wpedantic
- remove the && operator with TCP_CURR_IDX when computing no_csum
- make desc_id in tx_reap a uint32_t
- don't make vhost-kernel a required argument
Ammar Yasser (7):
tap: Move the tap_hdr file to a separate file
conf: Add context fields, epoll types and --vhost-kernel flag to pasta
virtio: Add the pasta vhost-net interface and implementation
tap: Implement the pasta vhost-net from-guest path
tap, tcp, udp: Prepare the to-guest path for vhost-net
tap: Implement the pasta vhost-net to-guest path
tap/tcp: Replace tcp_payload_used with a ring buffer style index
Makefile | 2 +-
conf.c | 19 +++
epoll_type.h | 4 +
passt.c | 9 ++
passt.h | 79 ++++++++++-
tap.c | 368 +++++++++++++++++++++++++++++++++++++++++++++------
tap.h | 47 ++-----
tap_hdr.h | 23 ++++
tcp_buf.c | 149 ++++++++++++++++-----
tcp_buf.h | 4 +
udp.c | 47 +++++--
udp.h | 3 +
util.c | 18 +++
util.h | 2 +
vhost.c | 295 +++++++++++++++++++++++++++++++++++++++++
vhost.h | 91 +++++++++++++
16 files changed, 1036 insertions(+), 124 deletions(-)
create mode 100644 tap_hdr.h
create mode 100644 vhost.c
create mode 100644 vhost.h
--
2.39.5 (Apple Git-154)