1 Generic networking statistics for netlink users
2 ======================================================================
3
4 Statistic counters are grouped into structs:
5
6 Struct TLV type Description
7 ----------------------------------------------------------------------
8 gnet_stats_basic TCA_STATS_BASIC Basic statistics
9 gnet_stats_rate_est TCA_STATS_RATE_EST Rate estimator
10 gnet_stats_queue TCA_STATS_QUEUE Queue statistics
11 none TCA_STATS_APP Application specific
12
13
14 Collecting:
15 -----------
16
17 Declare the statistic structs you need:
18 struct mystruct {
19 struct gnet_stats_basic bstats;
20 struct gnet_stats_queue qstats;
21 ...
22 };
23
24 Update statistics:
25 mystruct->tstats.packet++;
26 mystruct->qstats.backlog += skb->pkt_len;
27
28
29 Export to userspace (Dump):
30 ---------------------------
31
32 my_dumping_routine(struct sk_buff *skb, ...)
33 {
34 struct gnet_dump dump;
35
36 if (gnet_stats_start_copy(skb, TCA_STATS2, &mystruct->lock, &dump) < 0)
37 goto rtattr_failure;
38
39 if (gnet_stats_copy_basic(&dump, &mystruct->bstats) < 0 ||
40 gnet_stats_copy_queue(&dump, &mystruct->qstats) < 0 ||
41 gnet_stats_copy_app(&dump, &xstats, sizeof(xstats)) < 0)
42 goto rtattr_failure;
43
44 if (gnet_stats_finish_copy(&dump) < 0)
45 goto rtattr_failure;
46 ...
47 }
48
49 TCA_STATS/TCA_XSTATS backward compatibility:
50 --------------------------------------------
51
52 Prior users of struct tc_stats and xstats can maintain backward
53 compatibility by calling the compat wrappers to keep providing the
54 existing TLV types.
55
56 my_dumping_routine(struct sk_buff *skb, ...)
57 {
58 if (gnet_stats_start_copy_compat(skb, TCA_STATS2, TCA_STATS,
59 TCA_XSTATS, &mystruct->lock, &dump) < 0)
60 goto rtattr_failure;
61 ...
62 }
63
64 A struct tc_stats will be filled out during gnet_stats_copy_* calls
65 and appended to the skb. TCA_XSTATS is provided if gnet_stats_copy_app
66 was called.
67
68
69 Locking:
70 --------
71
72 Locks are taken before writing and released once all statistics have
73 been written. Locks are always released in case of an error. You
74 are responsible for making sure that the lock is initialized.
75
76
77 Rate Estimator:
78 --------------
79
80 0) Prepare an estimator attribute. Most likely this would be in user
81 space. The value of this TLV should contain a tc_estimator structure.
82 As usual, such a TLV nees to be 32 bit aligned and therefore the
83 length needs to be appropriately set etc. The estimator interval
84 and ewma log need to be converted to the appropriate values.
85 tc_estimator.c::tc_setup_estimator() is advisable to be used as the
86 conversion routine. It does a few clever things. It takes a time
87 interval in microsecs, a time constant also in microsecs and a struct
88 tc_estimator to be populated. The returned tc_estimator can be
89 transported to the kernel. Transfer such a structure in a TLV of type
90 TCA_RATE to your code in the kernel.
91
92 In the kernel when setting up:
93 1) make sure you have basic stats and rate stats setup first.
94 2) make sure you have initialized stats lock that is used to setup such
95 stats.
96 3) Now initialize a new estimator:
97
98 int ret = gen_new_estimator(my_basicstats,my_rate_est_stats,
99 mystats_lock, attr_with_tcestimator_struct);
100
101 if ret == 0
102 success
103 else
104 failed
105
106 From now on, everytime you dump my_rate_est_stats it will contain
107 uptodate info.
108
109 Once you are done, call gen_kill_estimator(my_basicstats,
110 my_rate_est_stats) Make sure that my_basicstats and my_rate_est_stats
111 are still valid (i.e still exist) at the time of making this call.
112
113
114 Authors:
115 --------
116 Thomas Graf <tgraf@suug.ch>
117 Jamal Hadi Salim <hadi@cyberus.ca>
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