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Add support for generic backpressure indicator for ratelimited

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transmit queues aswell as non-ratelimited ones.

Add the required structure bits in order to support a backpressure
indication with ratelimited connections aswell as non-ratelimited
ones. The backpressure indicator is a value between zero and 65535
inclusivly, indicating if the destination transmit queue is empty or
full respectivly. Applications can use this value as a decision point
for when to stop transmitting data to avoid endless ENOBUFS error
codes upon transmitting an mbuf. This indicator is also useful to
reduce the latency for ratelimited queues.

Reviewed by:		gallatin, kib, gnn
Differential Revision:	https://reviews.freebsd.org/D11518
Sponsored by:		Mellanox Technologies
This commit is contained in:
hselasky 2017-09-06 13:56:18 +00:00
parent b2f0b570ad
commit 7c2ab1d9f6
3 changed files with 41 additions and 2 deletions
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10
sys/net/if_var.h
View File

@ -183,7 +183,8 @@ struct if_encap_req {
struct m_snd_tag;
#define IF_SND_TAG_TYPE_RATE_LIMIT 0
#define IF_SND_TAG_TYPE_MAX 1
#define IF_SND_TAG_TYPE_UNLIMITED 1
#define IF_SND_TAG_TYPE_MAX 2
struct if_snd_tag_alloc_header {
uint32_t type; /* send tag type, see IF_SND_TAG_XXX */
@ -198,19 +199,26 @@ struct if_snd_tag_alloc_rate_limit {
struct if_snd_tag_rate_limit_params {
uint64_t max_rate; /* in bytes/s */
uint32_t queue_level; /* 0 (empty) .. 65535 (full) */
#define IF_SND_QUEUE_LEVEL_MIN 0
#define IF_SND_QUEUE_LEVEL_MAX 65535
uint32_t reserved; /* padding */
};
union if_snd_tag_alloc_params {
struct if_snd_tag_alloc_header hdr;
struct if_snd_tag_alloc_rate_limit rate_limit;
struct if_snd_tag_alloc_rate_limit unlimited;
};
union if_snd_tag_modify_params {
struct if_snd_tag_rate_limit_params rate_limit;
struct if_snd_tag_rate_limit_params unlimited;
};
union if_snd_tag_query_params {
struct if_snd_tag_rate_limit_params rate_limit;
struct if_snd_tag_rate_limit_params unlimited;
};
typedef int (if_snd_tag_alloc_t)(struct ifnet *, union if_snd_tag_alloc_params *,

32
sys/netinet/in_pcb.c
View File

@ -2796,6 +2796,35 @@ in_pcbquery_txrtlmt(struct inpcb *inp, uint32_t *p_max_pacing_rate)
return (error);
}
/*
* Query existing TX queue level based on the existing
* "inp->inp_snd_tag", if any.
*/
int
in_pcbquery_txrlevel(struct inpcb *inp, uint32_t *p_txqueue_level)
{
union if_snd_tag_query_params params = { };
struct m_snd_tag *mst;
struct ifnet *ifp;
int error;
mst = inp->inp_snd_tag;
if (mst == NULL)
return (EINVAL);
ifp = mst->ifp;
if (ifp == NULL)
return (EINVAL);
if (ifp->if_snd_tag_query == NULL)
return (EOPNOTSUPP);
error = ifp->if_snd_tag_query(mst, &params);
if (error == 0 && p_txqueue_level != NULL)
*p_txqueue_level = params.rate_limit.queue_level;
return (error);
}
/*
* Allocate a new TX rate limit send tag from the network interface
* given by the "ifp" argument and save it in "inp->inp_snd_tag":
@ -2805,7 +2834,8 @@ in_pcbattach_txrtlmt(struct inpcb *inp, struct ifnet *ifp,
uint32_t flowtype, uint32_t flowid, uint32_t max_pacing_rate)
{
union if_snd_tag_alloc_params params = {
.rate_limit.hdr.type = IF_SND_TAG_TYPE_RATE_LIMIT,
.rate_limit.hdr.type = (max_pacing_rate == -1U) ?
IF_SND_TAG_TYPE_UNLIMITED : IF_SND_TAG_TYPE_RATE_LIMIT,
.rate_limit.hdr.flowid = flowid,
.rate_limit.hdr.flowtype = flowtype,
.rate_limit.max_rate = max_pacing_rate,

1
sys/netinet/in_pcb.h
View File

@ -761,6 +761,7 @@ int in_pcbattach_txrtlmt(struct inpcb *, struct ifnet *, uint32_t, uint32_t, uin
void in_pcbdetach_txrtlmt(struct inpcb *);
int in_pcbmodify_txrtlmt(struct inpcb *, uint32_t);
int in_pcbquery_txrtlmt(struct inpcb *, uint32_t *);
int in_pcbquery_txrlevel(struct inpcb *, uint32_t *);
void in_pcboutput_txrtlmt(struct inpcb *, struct ifnet *, struct mbuf *);
void in_pcboutput_eagain(struct inpcb *);
#endif