| Message ID | 20230701063947.3422088-15-AVKrasnov@sberdevices.ru (mailing list archive) |
|---|---|
| State | RFC |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | vsock: MSG_ZEROCOPY flag support | expand |
On Sat, Jul 01, 2023 at 09:39:44AM +0300, Arseniy Krasnov wrote: >This adds description of MSG_ZEROCOPY flag support for AF_VSOCK type of >socket. > >Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> >--- > Documentation/networking/msg_zerocopy.rst | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > >diff --git a/Documentation/networking/msg_zerocopy.rst b/Documentation/networking/msg_zerocopy.rst >index b3ea96af9b49..34bc7ff411ce 100644 >--- a/Documentation/networking/msg_zerocopy.rst >+++ b/Documentation/networking/msg_zerocopy.rst >@@ -7,7 +7,8 @@ Intro > ===== > > The MSG_ZEROCOPY flag enables copy avoidance for socket send calls. >-The feature is currently implemented for TCP and UDP sockets. >+The feature is currently implemented for TCP, UDP and VSOCK (with >+virtio transport) sockets. > > > Opportunity and Caveats >@@ -174,7 +175,7 @@ read_notification() call in the previous snippet. A notification > is encoded in the standard error format, sock_extended_err. > > The level and type fields in the control data are protocol family >-specific, IP_RECVERR or IPV6_RECVERR. >+specific, IP_RECVERR or IPV6_RECVERR (for TCP or UDP socket). > > Error origin is the new type SO_EE_ORIGIN_ZEROCOPY. ee_errno is zero, > as explained before, to avoid blocking read and write system calls on >@@ -201,6 +202,7 @@ undefined, bar for ee_code, as discussed below. > > printf("completed: %u..%u\n", serr->ee_info, serr->ee_data); > >+For VSOCK socket, cmsg_level will be SOL_VSOCK and cmsg_type will be 0. Maybe better to move up, just under the previous change. By the way, should we define a valid type value for vsock (e.g. VSOCK_RECVERR)? > > Deferred copies > ~~~~~~~~~~~~~~~ >@@ -235,12 +237,15 @@ Implementation > Loopback > -------- > >+For TCP and UDP: > Data sent to local sockets can be queued indefinitely if the receive > process does not read its socket. Unbound notification latency is not > acceptable. For this reason all packets generated with MSG_ZEROCOPY > that are looped to a local socket will incur a deferred copy. This > includes looping onto packet sockets (e.g., tcpdump) and tun devices. > >+For VSOCK: >+Data path sent to local sockets is the same as for non-local sockets. > > Testing > ======= >@@ -254,3 +259,6 @@ instance when run with msg_zerocopy.sh between a veth pair across > namespaces, the test will not show any improvement. For testing, the > loopback restriction can be temporarily relaxed by making > skb_orphan_frags_rx identical to skb_orphan_frags. >+ >+For VSOCK type of socket example can be found in tools/testing/vsock/ >+vsock_test_zerocopy.c. For VSOCK socket, example can be found in tools/testing/vsock/vsock_test_zerocopy.c (we should leave the entire path on the same line) >-- >2.25.1 >
On 06.07.2023 20:06, Stefano Garzarella wrote: > On Sat, Jul 01, 2023 at 09:39:44AM +0300, Arseniy Krasnov wrote: >> This adds description of MSG_ZEROCOPY flag support for AF_VSOCK type of >> socket. >> >> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> >> --- >> Documentation/networking/msg_zerocopy.rst | 12 ++++++++++-- >> 1 file changed, 10 insertions(+), 2 deletions(-) >> >> diff --git a/Documentation/networking/msg_zerocopy.rst b/Documentation/networking/msg_zerocopy.rst >> index b3ea96af9b49..34bc7ff411ce 100644 >> --- a/Documentation/networking/msg_zerocopy.rst >> +++ b/Documentation/networking/msg_zerocopy.rst >> @@ -7,7 +7,8 @@ Intro >> ===== >> >> The MSG_ZEROCOPY flag enables copy avoidance for socket send calls. >> -The feature is currently implemented for TCP and UDP sockets. >> +The feature is currently implemented for TCP, UDP and VSOCK (with >> +virtio transport) sockets. >> >> >> Opportunity and Caveats >> @@ -174,7 +175,7 @@ read_notification() call in the previous snippet. A notification >> is encoded in the standard error format, sock_extended_err. >> >> The level and type fields in the control data are protocol family >> -specific, IP_RECVERR or IPV6_RECVERR. >> +specific, IP_RECVERR or IPV6_RECVERR (for TCP or UDP socket). >> >> Error origin is the new type SO_EE_ORIGIN_ZEROCOPY. ee_errno is zero, >> as explained before, to avoid blocking read and write system calls on >> @@ -201,6 +202,7 @@ undefined, bar for ee_code, as discussed below. >> >> printf("completed: %u..%u\n", serr->ee_info, serr->ee_data); >> >> +For VSOCK socket, cmsg_level will be SOL_VSOCK and cmsg_type will be 0. > > Maybe better to move up, just under the previous change. > > By the way, should we define a valid type value for vsock > (e.g. VSOCK_RECVERR)? Yes I think, I'll add it in the same patch which adds SOL_VSOCK. Thanks, Arseniy > >> >> Deferred copies >> ~~~~~~~~~~~~~~~ >> @@ -235,12 +237,15 @@ Implementation >> Loopback >> -------- >> >> +For TCP and UDP: >> Data sent to local sockets can be queued indefinitely if the receive >> process does not read its socket. Unbound notification latency is not >> acceptable. For this reason all packets generated with MSG_ZEROCOPY >> that are looped to a local socket will incur a deferred copy. This >> includes looping onto packet sockets (e.g., tcpdump) and tun devices. >> >> +For VSOCK: >> +Data path sent to local sockets is the same as for non-local sockets. >> >> Testing >> ======= >> @@ -254,3 +259,6 @@ instance when run with msg_zerocopy.sh between a veth pair across >> namespaces, the test will not show any improvement. For testing, the >> loopback restriction can be temporarily relaxed by making >> skb_orphan_frags_rx identical to skb_orphan_frags. >> + >> +For VSOCK type of socket example can be found in tools/testing/vsock/ >> +vsock_test_zerocopy.c. > > For VSOCK socket, example can be found in > tools/testing/vsock/vsock_test_zerocopy.c > > (we should leave the entire path on the same line) > >> -- >> 2.25.1 >> >
diff --git a/Documentation/networking/msg_zerocopy.rst b/Documentation/networking/msg_zerocopy.rst index b3ea96af9b49..34bc7ff411ce 100644 --- a/Documentation/networking/msg_zerocopy.rst +++ b/Documentation/networking/msg_zerocopy.rst @@ -7,7 +7,8 @@ Intro ===== The MSG_ZEROCOPY flag enables copy avoidance for socket send calls. -The feature is currently implemented for TCP and UDP sockets. +The feature is currently implemented for TCP, UDP and VSOCK (with +virtio transport) sockets. Opportunity and Caveats @@ -174,7 +175,7 @@ read_notification() call in the previous snippet. A notification is encoded in the standard error format, sock_extended_err. The level and type fields in the control data are protocol family -specific, IP_RECVERR or IPV6_RECVERR. +specific, IP_RECVERR or IPV6_RECVERR (for TCP or UDP socket). Error origin is the new type SO_EE_ORIGIN_ZEROCOPY. ee_errno is zero, as explained before, to avoid blocking read and write system calls on @@ -201,6 +202,7 @@ undefined, bar for ee_code, as discussed below. printf("completed: %u..%u\n", serr->ee_info, serr->ee_data); +For VSOCK socket, cmsg_level will be SOL_VSOCK and cmsg_type will be 0. Deferred copies ~~~~~~~~~~~~~~~ @@ -235,12 +237,15 @@ Implementation Loopback -------- +For TCP and UDP: Data sent to local sockets can be queued indefinitely if the receive process does not read its socket. Unbound notification latency is not acceptable. For this reason all packets generated with MSG_ZEROCOPY that are looped to a local socket will incur a deferred copy. This includes looping onto packet sockets (e.g., tcpdump) and tun devices. +For VSOCK: +Data path sent to local sockets is the same as for non-local sockets. Testing ======= @@ -254,3 +259,6 @@ instance when run with msg_zerocopy.sh between a veth pair across namespaces, the test will not show any improvement. For testing, the loopback restriction can be temporarily relaxed by making skb_orphan_frags_rx identical to skb_orphan_frags. + +For VSOCK type of socket example can be found in tools/testing/vsock/ +vsock_test_zerocopy.c.
This adds description of MSG_ZEROCOPY flag support for AF_VSOCK type of socket. Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> --- Documentation/networking/msg_zerocopy.rst | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)