January 2023 - dev

[PATCH v2 00/18] RFC: Unify and simplify tap send path
by David Gibson 05 Jan '23

05 Jan '23

Although we have an abstraction for the "slow path" (DHCP, NDP) guest bound packets, the TCP and UDP forwarding paths write directly to the tap fd. However, it turns out how they send frames to the tap device is more similar than it originally appears. This series unifies the low-level tap send functions for TCP and UDP, and makes some clean ups along the way. This is based on my earlier outstanding series. Changes since v1: * Abstract tap header construction as well as frame send (a number of new patches) * Remove unneeded flags buf_bytes globals as well * Fix bug where we weren't correctly setting iov_len after the move to giving variable sized iovecs to send_frames(). David Gibson (18): pcap: Introduce pcap_frame() helper pcap: Replace pcapm() with pcap_multiple() tcp: Combine two parts of passt tap send path together tcp: Don't keep compute total bytes in a message until we need it tcp: Improve interface to tcp_l2_buf_flush() tcp: Combine two parts of pasta tap send path together tap, tcp: Move tap send path to tap.c util: Introduce hton*_constant() in place of #ifdefs tcp, udp: Use named field initializers in iov_init functions util: Parameterize ethernet header initializer macro tcp: Remove redundant and incorrect initialization from *_iov_init() tcp: Consolidate calculation of total frame size tap: Add "tap headers" abstraction tcp: Use abstracted tap header tap: Use different io vector bases depending on tap type udp: Use abstracted tap header udp: Use tap_send_frames() tap: Improve handling of partial frame sends dhcpv6.c | 50 +++-------- pcap.c | 78 +++++------------ pcap.h | 3 +- tap.c | 123 +++++++++++++++++++++++++++ tap.h | 54 ++++++++++++ tcp.c | 254 +++++++++++++------------------------------------------ udp.c | 213 ++++++---------------------------------------- udp.h | 2 +- util.h | 47 ++-------- 9 files changed, 303 insertions(+), 521 deletions(-) -- 2.38.1

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[PATCH] tcp: Explicitly check option length field values in tcp_opt_get()
by Stefano Brivio 05 Jan '23

05 Jan '23

Reported by Coverity (CWE-606, Untrusted loop bound), and actually harmless because we'll exit the option-scanning loop if the remaining length is not enough for a new option, instead of reading past the header. In any case, it looks like a good idea to explicitly check for reasonable values of option lengths. Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com> --- tcp.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/tcp.c b/tcp.c index 26037b3..1e0a338 100644 --- a/tcp.c +++ b/tcp.c @@ -1117,6 +1117,10 @@ static int tcp_opt_get(const char *opts, size_t len, uint8_t type_find, break; default: type = *(opts++); + + if (*(uint8_t *)opts < 2 || *(uint8_t *)opts > len) + return -1; + optlen = *(opts++) - 2; len -= 2; -- 2.35.1

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[PATCH v3 0/8] Don't use additional sockets for receiving "spliced" UDP communications
by David Gibson 05 Jan '23

05 Jan '23

At present, the UDP "splice" and "tap" paths are quite separate. We have separate sockets to receive packets bound for the tap and splice paths. This leads to some code duplication, and extra open sockets. This series partially unifies the two paths, allowing us to use a single (host side) socket, bound to 0.0.0.0 or :: to receive packets for both cases. Changes since v2: * Don't receive multiple packets at once for pasta mode - seems to hurt throughput on balance. * Add some comments clarifying reasoning here. Changes since v1: * Renamed udp_localname[46] to udp[46]_localname * Allow handling of UDP port 0 * Fix a bug which could misidentify certain v6 packets as v4-spliceable * Some minor cosmetic fixes to code and commit messages David Gibson (8): udp: Move sending pasta tap frames to the end of udp_sock_handler() udp: Split sending to passt tap interface into separate function udp: Split receive from preparation and send in udp_sock_handler() udp: Don't handle tap receive batch size calculation within a #define udp: Pre-populate msg_names with local address udp: Unify udp_sock_handler_splice() with udp_sock_handler() udp: Decide whether to "splice" per datagram rather than per socket udp: Don't use separate sockets to listen for spliced packets udp.c | 389 ++++++++++++++++++++++++++++++--------------------------- udp.h | 2 +- util.h | 7 ++ 3 files changed, 214 insertions(+), 184 deletions(-) -- 2.39.0

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[PATCH] test/perf/pasta_tcp: Add host to namespace cases for traffic via tap
by Stefano Brivio 05 Jan '23

05 Jan '23

Similarly to UDP cases, these were missing as it wasn't clear, when the other tests were introduced, if using the global address of a namespace, from the host, should have resulted in connections being routed via the tap interface. Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com> --- test/perf/pasta_tcp | 57 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) diff --git a/test/perf/pasta_tcp b/test/perf/pasta_tcp index 1847c83..8ebb25c 100644 --- a/test/perf/pasta_tcp +++ b/test/perf/pasta_tcp @@ -240,4 +240,61 @@ nsout LAT tcp_crr --nolog -P 10003 -C 10013 -4 -c -H __GW__ | sed -n 's/^through hostw lat __LAT__ 1500 500 + +tr TCP throughput over IPv6: host to ns +nsout IFNAME ip -j link show | jq -rM '.[] | select(.link_type == "ether").ifname' +nsout ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.scope == "global" and .prefixlen == 64).local' +bw - +bw - +bw - +iperf3 BW host ns __ADDR6__ 100${i}2 __THREADS__ __TIME__ __OPTS__ +bw __BW__ 8.0 10.0 + +tl TCP RR latency over IPv6: host to ns +lat - +lat - +lat - +nsb tcp_rr --nolog -P 10002 -C 10012 -6 +hout LAT tcp_rr --nolog -P 10002 -C 10012 -6 -c -H __ADDR6__ | sed -n 's/^throughput=$.*$/\1/p' +nsw +lat __LAT__ 150 100 + +tl TCP CRR latency over IPv6: host to ns +lat - +lat - +lat - +sleep 1 +nsb tcp_crr --nolog -P 10002 -C 10012 -6 +hout LAT tcp_crr --nolog -P 10002 -C 10012 -6 -c -H __ADDR6__ | sed -n 's/^throughput=$.*$/\1/p' +nsw +lat __LAT__ 5000 10000 + + +tr TCP throughput over IPv4: host to ns +nsout ADDR ip -j -4 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[0].local' +bw - +bw - +bw - +iperf3 BW host ns __ADDR__ 100${i}2 __THREADS__ __TIME__ __OPTS__ +bw __BW__ 8.0 10.0 + +tl TCP RR latency over IPv4: host to ns +lat - +lat - +lat - +nsb tcp_rr --nolog -P 10002 -C 10012 -4 +hout LAT tcp_rr --nolog -P 10002 -C 10012 -4 -c -H __ADDR__ | sed -n 's/^throughput=$.*$/\1/p' +nsw +lat __LAT__ 150 100 + +tl TCP CRR latency over IPv4: host to ns +lat - +lat - +lat - +sleep 1 +nsb tcp_crr --nolog -P 10002 -C 10012 -4 +hout LAT tcp_crr --nolog -P 10002 -C 10012 -4 -c -H __ADDR__ | sed -n 's/^throughput=$.*$/\1/p' +nsw +lat __LAT__ 5000 10000 + te -- 2.35.1

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[PATCH 0/8] Don't use additional sockets for receiving "spliced" UDP communications
by David Gibson 04 Jan '23

04 Jan '23

At present, the UDP "splice" and "tap" paths are quite separate. We have separate sockets to receive packets bound for the tap and splice paths. This leads to some code duplication, and extra open sockets. This series partially unifies the two paths, allowing us to use a single (host side) socket, bound to 0.0.0.0 or :: to receive packets for both cases. This is based on my earlier series with some fixes for the tap path. David Gibson (8): udp: Move sending pasta tap frames to the end of udp_sock_handler() udp: Split sending to passt tap interface into separate function udp: Split receive from preparation and send in udp_sock_handler() udp: Receive multiple datagrams at once on the pasta sock->tap path udp: Pre-populate msg_names with local address udp: Unify udp_sock_handler_splice() with udp_sock_handler() udp: Decide whether to "splice" per datagram rather than per socket udp: Don't use separate sockets to listen for spliced packets udp.c | 382 ++++++++++++++++++++++++++++++--------------------------- udp.h | 2 +- util.h | 7 ++ 3 files changed, 207 insertions(+), 184 deletions(-) -- 2.38.1

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[PATCH] test/perf/pasta_udp: Add host to namespace cases for traffic via tap
by Stefano Brivio 04 Jan '23

04 Jan '23

These were missing as it wasn't clear, when the other tests were introduced, if using the global address of a namespace, from the host, should have resulted in traffic being routed via the tap interface (as opposed to the loopback interface). We now clarified that's actually the case. Use same values and thresholds as the tests for loopback traffic, as throughput figures currently indicate there isn't much difference. Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com> --- Contrary to what I stated a while ago, there's actually no need to adapt the "code" writing the JavaScript snippets for performance reports -- the trick is simply to keep those ordered like the previous ones, and we'll get the right output. test/perf/pasta_udp | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/test/perf/pasta_udp b/test/perf/pasta_udp index 27ea724..112d70d 100644 --- a/test/perf/pasta_udp +++ b/test/perf/pasta_udp @@ -179,4 +179,41 @@ nsout LAT udp_rr --nolog -P 10003 -C 10013 -4 -c -H __GW__ | sed -n 's/^throughp hostw lat __LAT__ 200 150 + +tr UDP throughput over IPv6: host to ns +nsout IFNAME ip -j link show | jq -rM '.[] | select(.link_type == "ether").ifname' +nsout ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.scope == "global" and .prefixlen == 64).local' +bw - +bw - +bw - +iperf3 BW host ns __ADDR6__ 100${i}2 __THREADS__ __TIME__ __OPTS__ -b 15G +bw __BW__ 7.0 9.0 + +tl UDP RR latency over IPv6: host to ns +lat - +lat - +lat - +nsb udp_rr --nolog -P 10002 -C 10012 -6 +hout LAT udp_rr --nolog -P 10002 -C 10012 -6 -c -H __ADDR6__ | sed -n 's/^throughput=$.*$/\1/p' +nsw +lat __LAT__ 200 150 + + +tr UDP throughput over IPv4: host to ns +nsout ADDR ip -j -4 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[0].local' +bw - +bw - +bw - +iperf3 BW host ns __ADDR__ 100${i}2 __THREADS__ __TIME__ __OPTS__ -b 15G +bw __BW__ 7.0 9.0 + +tl UDP RR latency over IPv4: host to ns +lat - +lat - +lat - +nsb udp_rr --nolog -P 10002 -C 10012 -4 +hout LAT udp_rr --nolog -P 10002 -C 10012 -4 -c -H __ADDR__ | sed -n 's/^throughput=$.*$/\1/p' +nsw +lat __LAT__ 200 150 + te -- 2.35.1

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