linux/include/net/psample.h
Adrian Moreno 7b1b2b60c6 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>
2024-07-05 17:45:47 -07:00

55 lines
1.1 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __NET_PSAMPLE_H
#define __NET_PSAMPLE_H
#include <uapi/linux/psample.h>
#include <linux/list.h>
struct psample_group {
struct list_head list;
struct net *net;
u32 group_num;
u32 refcount;
u32 seq;
struct rcu_head rcu;
};
struct psample_metadata {
u32 trunc_size;
int in_ifindex;
int out_ifindex;
u16 out_tc;
u64 out_tc_occ; /* bytes */
u64 latency; /* nanoseconds */
u8 out_tc_valid:1,
out_tc_occ_valid:1,
latency_valid:1,
rate_as_probability:1,
unused:4;
const u8 *user_cookie;
u32 user_cookie_len;
};
struct psample_group *psample_group_get(struct net *net, u32 group_num);
void psample_group_take(struct psample_group *group);
void psample_group_put(struct psample_group *group);
struct sk_buff;
#if IS_ENABLED(CONFIG_PSAMPLE)
void psample_sample_packet(struct psample_group *group, struct sk_buff *skb,
u32 sample_rate, const struct psample_metadata *md);
#else
static inline void psample_sample_packet(struct psample_group *group,
struct sk_buff *skb, u32 sample_rate,
const struct psample_metadata *md)
{
}
#endif
#endif /* __NET_PSAMPLE_H */