diff options
| author | Adrian Moreno <amorenoz@redhat.com> | 2024-07-04 10:56:55 +0200 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2024-07-05 17:45:47 -0700 |
| commit | 7b1b2b60c63f070e0dfbe072ccaae13168b38d01 (patch) | |
| tree | 68420e693c20aacac7c60dd3407418c29126787b | |
| parent | c35d86a23029f1186e3c7a65df7c38b762fb0434 (diff) | |
net: psample: allow using rate as probability
Although not explicitly documented in the psample module itself, the
definition of PSAMPLE_ATTR_SAMPLE_RATE seems inherited from act_sample.
Quoting tc-sample(8):
"RATE of 100 will lead to an average of one sampled packet out of every
100 observed."
With this semantics, the rates that we can express with an unsigned
32-bits number are very unevenly distributed and concentrated towards
"sampling few packets".
For example, we can express a probability of 2.32E-8% but we
cannot express anything between 100% and 50%.
For sampling applications that are capable of sampling a decent
amount of packets, this sampling rate semantics is not very useful.
Add a new flag to the uAPI that indicates that the sampling rate is
expressed in scaled probability, this is:
- 0 is 0% probability, no packets get sampled.
- U32_MAX is 100% probability, all packets get sampled.
Reviewed-by: Aaron Conole <aconole@redhat.com>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Adrian Moreno <amorenoz@redhat.com>
Link: https://patch.msgid.link/20240704085710.353845-5-amorenoz@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | include/net/psample.h | 3 | ||||
| -rw-r--r-- | include/uapi/linux/psample.h | 10 | ||||
| -rw-r--r-- | net/psample/psample.c | 3 |
3 files changed, 14 insertions, 2 deletions
diff --git a/include/net/psample.h b/include/net/psample.h index 2ac71260a546..c52e9ebd88dd 100644 --- a/include/net/psample.h +++ b/include/net/psample.h @@ -24,7 +24,8 @@ struct psample_metadata { u8 out_tc_valid:1, out_tc_occ_valid:1, latency_valid:1, - unused:5; + rate_as_probability:1, + unused:4; const u8 *user_cookie; u32 user_cookie_len; }; diff --git a/include/uapi/linux/psample.h b/include/uapi/linux/psample.h index e80637e1d97b..b765f0e81f20 100644 --- a/include/uapi/linux/psample.h +++ b/include/uapi/linux/psample.h @@ -8,7 +8,11 @@ enum { PSAMPLE_ATTR_ORIGSIZE, PSAMPLE_ATTR_SAMPLE_GROUP, PSAMPLE_ATTR_GROUP_SEQ, - PSAMPLE_ATTR_SAMPLE_RATE, + PSAMPLE_ATTR_SAMPLE_RATE, /* u32, ratio between observed and + * sampled packets or scaled probability + * if PSAMPLE_ATTR_SAMPLE_PROBABILITY + * is set. + */ PSAMPLE_ATTR_DATA, PSAMPLE_ATTR_GROUP_REFCOUNT, PSAMPLE_ATTR_TUNNEL, @@ -20,6 +24,10 @@ enum { PSAMPLE_ATTR_TIMESTAMP, /* u64, nanoseconds */ PSAMPLE_ATTR_PROTO, /* u16 */ PSAMPLE_ATTR_USER_COOKIE, /* binary, user provided data */ + PSAMPLE_ATTR_SAMPLE_PROBABILITY,/* no argument, interpret rate in + * PSAMPLE_ATTR_SAMPLE_RATE as a + * probability scaled 0 - U32_MAX. + */ __PSAMPLE_ATTR_MAX }; diff --git a/net/psample/psample.c b/net/psample/psample.c index 1c76f3e48dcd..f48b5b9cd409 100644 --- a/net/psample/psample.c +++ b/net/psample/psample.c @@ -497,6 +497,9 @@ void psample_sample_packet(struct psample_group *group, struct sk_buff *skb, md->user_cookie)) goto error; + if (md->rate_as_probability) + nla_put_flag(skb, PSAMPLE_ATTR_SAMPLE_PROBABILITY); + genlmsg_end(nl_skb, data); genlmsg_multicast_netns(&psample_nl_family, group->net, nl_skb, 0, PSAMPLE_NL_MCGRP_SAMPLE, GFP_ATOMIC); |