| Message ID | 20250220072940.99994-1-kerneljasonxing@gmail.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | net-timestamp: bpf extension to equip applications transparently | expand |
Jason Xing wrote: > "Timestamping is key to debugging network stack latency. With > SO_TIMESTAMPING, bugs that are otherwise incorrectly assumed to be > network issues can be attributed to the kernel." This is extracted > from the talk "SO_TIMESTAMPING: Powering Fleetwide RPC Monitoring" > addressed by Willem de Bruijn at netdevconf 0x17). > > There are a few areas that need optimization with the consideration of > easier use and less performance impact, which I highlighted and mainly > discussed at netconf 2024 with Willem de Bruijn and John Fastabend: > uAPI compatibility, extra system call overhead, and the need for > application modification. I initially managed to solve these issues > by writing a kernel module that hooks various key functions. However, > this approach is not suitable for the next kernel release. Therefore, > a BPF extension was proposed. During recent period, Martin KaFai Lau > provides invaluable suggestions about BPF along the way. Many thanks > here! > > This series adds the BPF networking timestamping infrastructure through > reusing most of the tx timestamping callback that is currently enabled > by the SO_TIMESTAMPING.. This series also adds TX timestamping support > for TCP. The RX timestamping and UDP support will be added in the future. This series addresses all my feedback. The timestamping patches all have my Reviewed-by. The BPF parts I am less qualified to review. They LGTM, but I defer to Martin as the expert reviewer.
Hello: This series was applied to bpf/bpf-next.git (net) by Martin KaFai Lau <martin.lau@kernel.org>: On Thu, 20 Feb 2025 15:29:28 +0800 you wrote: > "Timestamping is key to debugging network stack latency. With > SO_TIMESTAMPING, bugs that are otherwise incorrectly assumed to be > network issues can be attributed to the kernel." This is extracted > from the talk "SO_TIMESTAMPING: Powering Fleetwide RPC Monitoring" > addressed by Willem de Bruijn at netdevconf 0x17). > > There are a few areas that need optimization with the consideration of > easier use and less performance impact, which I highlighted and mainly > discussed at netconf 2024 with Willem de Bruijn and John Fastabend: > uAPI compatibility, extra system call overhead, and the need for > application modification. I initially managed to solve these issues > by writing a kernel module that hooks various key functions. However, > this approach is not suitable for the next kernel release. Therefore, > a BPF extension was proposed. During recent period, Martin KaFai Lau > provides invaluable suggestions about BPF along the way. Many thanks > here! > > [...] Here is the summary with links: - [bpf-next,v13,01/12] bpf: add networking timestamping support to bpf_get/setsockopt() (no matching commit) - [bpf-next,v13,02/12] bpf: prepare the sock_ops ctx and call bpf prog for TX timestamping https://git.kernel.org/bpf/bpf-next/c/df600f3b1d79 - [bpf-next,v13,03/12] bpf: prevent unsafe access to the sock fields in the BPF timestamping callback https://git.kernel.org/bpf/bpf-next/c/fd93eaffb3f9 - [bpf-next,v13,04/12] bpf: disable unsafe helpers in TX timestamping callbacks https://git.kernel.org/bpf/bpf-next/c/2958624b2530 - [bpf-next,v13,05/12] net-timestamp: prepare for isolating two modes of SO_TIMESTAMPING https://git.kernel.org/bpf/bpf-next/c/aa290f93a4af - [bpf-next,v13,06/12] bpf: add BPF_SOCK_OPS_TSTAMP_SCHED_CB callback https://git.kernel.org/bpf/bpf-next/c/6b98ec7e882a - [bpf-next,v13,07/12] bpf: add BPF_SOCK_OPS_TSTAMP_SND_SW_CB callback https://git.kernel.org/bpf/bpf-next/c/ecebb17ad818 - [bpf-next,v13,08/12] bpf: add BPF_SOCK_OPS_TSTAMP_SND_HW_CB callback https://git.kernel.org/bpf/bpf-next/c/2deaf7f42b8c - [bpf-next,v13,09/12] bpf: add BPF_SOCK_OPS_TSTAMP_ACK_CB callback https://git.kernel.org/bpf/bpf-next/c/b3b81e6b009d - [bpf-next,v13,10/12] bpf: add BPF_SOCK_OPS_TSTAMP_SENDMSG_CB callback https://git.kernel.org/bpf/bpf-next/c/c9525d240c81 - [bpf-next,v13,11/12] bpf: support selective sampling for bpf timestamping https://git.kernel.org/bpf/bpf-next/c/59422464266f - [bpf-next,v13,12/12] selftests/bpf: add simple bpf tests in the tx path for timestamping feature https://git.kernel.org/bpf/bpf-next/c/f4924aec58dd You are awesome, thank you!
On 2/20/25 7:32 AM, Willem de Bruijn wrote: > Jason Xing wrote: >> "Timestamping is key to debugging network stack latency. With >> SO_TIMESTAMPING, bugs that are otherwise incorrectly assumed to be >> network issues can be attributed to the kernel." This is extracted >> from the talk "SO_TIMESTAMPING: Powering Fleetwide RPC Monitoring" >> addressed by Willem de Bruijn at netdevconf 0x17). >> >> There are a few areas that need optimization with the consideration of >> easier use and less performance impact, which I highlighted and mainly >> discussed at netconf 2024 with Willem de Bruijn and John Fastabend: >> uAPI compatibility, extra system call overhead, and the need for >> application modification. I initially managed to solve these issues >> by writing a kernel module that hooks various key functions. However, >> this approach is not suitable for the next kernel release. Therefore, >> a BPF extension was proposed. During recent period, Martin KaFai Lau >> provides invaluable suggestions about BPF along the way. Many thanks >> here! >> >> This series adds the BPF networking timestamping infrastructure through >> reusing most of the tx timestamping callback that is currently enabled >> by the SO_TIMESTAMPING.. This series also adds TX timestamping support >> for TCP. The RX timestamping and UDP support will be added in the future. Thanks for working on this BPF feature. Applied. > This series addresses all my feedback. > > The timestamping patches all have my Reviewed-by. Thanks to Willem and other reviewers for their input in this long thread across many revisions.
On Fri, Feb 21, 2025 at 7:02 AM Martin KaFai Lau <martin.lau@linux.dev> wrote: > > On 2/20/25 7:32 AM, Willem de Bruijn wrote: > > Jason Xing wrote: > >> "Timestamping is key to debugging network stack latency. With > >> SO_TIMESTAMPING, bugs that are otherwise incorrectly assumed to be > >> network issues can be attributed to the kernel." This is extracted > >> from the talk "SO_TIMESTAMPING: Powering Fleetwide RPC Monitoring" > >> addressed by Willem de Bruijn at netdevconf 0x17). > >> > >> There are a few areas that need optimization with the consideration of > >> easier use and less performance impact, which I highlighted and mainly > >> discussed at netconf 2024 with Willem de Bruijn and John Fastabend: > >> uAPI compatibility, extra system call overhead, and the need for > >> application modification. I initially managed to solve these issues > >> by writing a kernel module that hooks various key functions. However, > >> this approach is not suitable for the next kernel release. Therefore, > >> a BPF extension was proposed. During recent period, Martin KaFai Lau > >> provides invaluable suggestions about BPF along the way. Many thanks > >> here! > >> > >> This series adds the BPF networking timestamping infrastructure through > >> reusing most of the tx timestamping callback that is currently enabled > >> by the SO_TIMESTAMPING.. This series also adds TX timestamping support > >> for TCP. The RX timestamping and UDP support will be added in the future. > > Thanks for working on this BPF feature. Applied. Thanks Martin for sharing invaluable and precious knowledge on BPF design !!! Thanks Willem for great effort on suggesting from the insightful perspective of the networking area !!! > > > This series addresses all my feedback. > > > > The timestamping patches all have my Reviewed-by. > > Thanks to Willem and other reviewers for their input in this long thread across > many revisions. Thanks everyone from the bottom of my heart :) Thanks, Jason
"Timestamping is key to debugging network stack latency. With SO_TIMESTAMPING, bugs that are otherwise incorrectly assumed to be network issues can be attributed to the kernel." This is extracted from the talk "SO_TIMESTAMPING: Powering Fleetwide RPC Monitoring" addressed by Willem de Bruijn at netdevconf 0x17). There are a few areas that need optimization with the consideration of easier use and less performance impact, which I highlighted and mainly discussed at netconf 2024 with Willem de Bruijn and John Fastabend: uAPI compatibility, extra system call overhead, and the need for application modification. I initially managed to solve these issues by writing a kernel module that hooks various key functions. However, this approach is not suitable for the next kernel release. Therefore, a BPF extension was proposed. During recent period, Martin KaFai Lau provides invaluable suggestions about BPF along the way. Many thanks here! This series adds the BPF networking timestamping infrastructure through reusing most of the tx timestamping callback that is currently enabled by the SO_TIMESTAMPING.. This series also adds TX timestamping support for TCP. The RX timestamping and UDP support will be added in the future. --- v12 Link: https://lore.kernel.org/all/20250218050125.73676-1-kerneljasonxing@gmail.com/ 1. use u8 for sk_bpf_cb_flags and adjust its position to fill a hole exactly. It will not introduce any hole. 2. rename the CB flags 3. update SK_BPF_CB_TX_TIMESTAMPING enum in tools/include/uapi/linux/bpf.h v11 Link: https://lore.kernel.org/all/20250214010038.54131-1-kerneljasonxing@gmail.com/ 1. remove the unused variable 'sk' 2. correct grammar mistakes 3. move two places where using SKBTX_HW_TSTAMP_NOBPF from patch 9 to 8. v10 Link: https://lore.kernel.org/all/20250212061855.71154-1-kerneljasonxing@gmail.com/ 1. rename hwts with hwtimestamp 2. use subtest and pid filter in selftest 3. use 'tcb->txstamp_ack |= TSTAMP_ACK_SK' v9 Link: https://lore.kernel.org/all/20250208103220.72294-1-kerneljasonxing@gmail.com/ 1. set the hwtstamp to skb when the skb enters into the hw SND case 2. fix co-existence problem in patch 9 and add corresponding check in patch 12. 3. refine some commit messages and titles v8 Link: https://lore.kernel.org/all/20250128084620.57547-1-kerneljasonxing@gmail.com/ 1. adjust some commit messages and titles 2. add sk cookie in selftests 3. handle the NULL pointer in hwstamp 4. use kfunc to do selective sampling v7 Link: https://lore.kernel.org/all/20250121012901.87763-1-kerneljasonxing@gmail.com/ 1. target bpf-next tree 2. simplely and directly stop timestamping callbacks calling a few BPF CALLS due to safety concern. 3. add more new testcases and adjust the existing testcases 4. revise some comments of new timestamping callbacks 5. remove a few BPF CGROUP locks RFC v6 In the meantime, any suggestions and reviews are welcome! Link: https://lore.kernel.org/all/20250112113748.73504-1-kerneljasonxing@gmail.com/ 1. handle those safety problem by using the correct method. 2. support bpf_getsockopt. 3. adjust the position of BPF_SOCK_OPS_TS_TCP_SND_CB 4. fix mishandling the hardware timestamp error 5. add more corresponding tests v5 Link: https://lore.kernel.org/all/20241207173803.90744-1-kerneljasonxing@gmail.com/ 1. handle the safety issus when someone tries to call unrelated bpf helpers. 2. avoid adding direct function call in the hot path like __dev_queue_xmit() 3. remove reporting the hardware timestamp and tskey since they can be fetched through the existing helper with the help of bpf_skops_init_skb(), please see the selftest. 4. add new sendmsg callback in tcp_sendmsg, and introduce tskey_bpf used by bpf program to correlate tcp_sendmsg with other hook points in patch [13/15]. v4 Link: https://lore.kernel.org/all/20241028110535.82999-1-kerneljasonxing@gmail.com/ 1. introduce sk->sk_bpf_cb_flags to let user use bpf_setsockopt() (Martin) 2. introduce SKBTX_BPF to enable the bpf SO_TIMESTAMPING feature (Martin) 3. introduce bpf map in tests (Martin) 4. I choose to make this series as simple as possible, so I only support most cases in the tx path for TCP protocol. v3 Link: https://lore.kernel.org/all/20241012040651.95616-1-kerneljasonxing@gmail.com/ 1. support UDP proto by introducing a new generation point. 2. for OPT_ID, introducing sk_tskey_bpf_offset to compute the delta between the current socket key and bpf socket key. It is desiged for UDP, which also applies to TCP. 3. support bpf_getsockopt() 4. use cgroup static key instead. 5. add one simple bpf selftest to show how it can be used. 6. remove the rx support from v2 because the number of patches could exceed the limit of one series. V2 Link: https://lore.kernel.org/all/20241008095109.99918-1-kerneljasonxing@gmail.com/ 1. Introduce tsflag requestors so that we are able to extend more in the future. Besides, it enables TX flags for bpf extension feature separately without breaking users. It is suggested by Vadim Fedorenko. 2. introduce a static key to control the whole feature. (Willem) 3. Open the gate of bpf_setsockopt for the SO_TIMESTAMPING feature in some TX/RX cases, not all the cases. Jason Xing (12): bpf: add networking timestamping support to bpf_get/setsockopt() bpf: prepare the sock_ops ctx and call bpf prog for TX timestamping bpf: prevent unsafe access to the sock fields in the BPF timestamping callback bpf: disable unsafe helpers in TX timestamping callbacks net-timestamp: prepare for isolating two modes of SO_TIMESTAMPING bpf: add BPF_SOCK_OPS_TSTAMP_SCHED_CB callback bpf: add BPF_SOCK_OPS_TSTAMP_SND_SW_CB callback bpf: add BPF_SOCK_OPS_TSTAMP_SND_HW_CB callback bpf: add BPF_SOCK_OPS_TSTAMP_ACK_CB callback bpf: add BPF_SOCK_OPS_TSTAMP_SENDMSG_CB callback bpf: support selective sampling for bpf timestamping selftests/bpf: add simple bpf tests in the tx path for timestamping feature include/linux/filter.h | 1 + include/linux/skbuff.h | 12 +- include/net/sock.h | 10 + include/net/tcp.h | 7 +- include/uapi/linux/bpf.h | 31 +++ kernel/bpf/btf.c | 1 + net/core/dev.c | 3 +- net/core/filter.c | 79 +++++- net/core/skbuff.c | 53 ++++ net/core/sock.c | 14 + net/dsa/user.c | 2 +- net/ipv4/tcp.c | 6 +- net/ipv4/tcp_input.c | 2 + net/ipv4/tcp_output.c | 2 + net/socket.c | 2 +- tools/include/uapi/linux/bpf.h | 31 +++ .../bpf/prog_tests/net_timestamping.c | 239 +++++++++++++++++ .../selftests/bpf/progs/net_timestamping.c | 248 ++++++++++++++++++ 18 files changed, 729 insertions(+), 14 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/net_timestamping.c create mode 100644 tools/testing/selftests/bpf/progs/net_timestamping.c