gen_stats.rst (3945B)
1.. SPDX-License-Identifier: GPL-2.0 2 3=============================================== 4Generic networking statistics for netlink users 5=============================================== 6 7Statistic counters are grouped into structs: 8 9==================== ===================== ===================== 10Struct TLV type Description 11==================== ===================== ===================== 12gnet_stats_basic TCA_STATS_BASIC Basic statistics 13gnet_stats_rate_est TCA_STATS_RATE_EST Rate estimator 14gnet_stats_queue TCA_STATS_QUEUE Queue statistics 15none TCA_STATS_APP Application specific 16==================== ===================== ===================== 17 18 19Collecting: 20----------- 21 22Declare the statistic structs you need:: 23 24 struct mystruct { 25 struct gnet_stats_basic bstats; 26 struct gnet_stats_queue qstats; 27 ... 28 }; 29 30Update statistics, in dequeue() methods only, (while owning qdisc->running):: 31 32 mystruct->tstats.packet++; 33 mystruct->qstats.backlog += skb->pkt_len; 34 35 36Export to userspace (Dump): 37--------------------------- 38 39:: 40 41 my_dumping_routine(struct sk_buff *skb, ...) 42 { 43 struct gnet_dump dump; 44 45 if (gnet_stats_start_copy(skb, TCA_STATS2, &mystruct->lock, &dump, 46 TCA_PAD) < 0) 47 goto rtattr_failure; 48 49 if (gnet_stats_copy_basic(&dump, &mystruct->bstats) < 0 || 50 gnet_stats_copy_queue(&dump, &mystruct->qstats) < 0 || 51 gnet_stats_copy_app(&dump, &xstats, sizeof(xstats)) < 0) 52 goto rtattr_failure; 53 54 if (gnet_stats_finish_copy(&dump) < 0) 55 goto rtattr_failure; 56 ... 57 } 58 59TCA_STATS/TCA_XSTATS backward compatibility: 60-------------------------------------------- 61 62Prior users of struct tc_stats and xstats can maintain backward 63compatibility by calling the compat wrappers to keep providing the 64existing TLV types:: 65 66 my_dumping_routine(struct sk_buff *skb, ...) 67 { 68 if (gnet_stats_start_copy_compat(skb, TCA_STATS2, TCA_STATS, 69 TCA_XSTATS, &mystruct->lock, &dump, 70 TCA_PAD) < 0) 71 goto rtattr_failure; 72 ... 73 } 74 75A struct tc_stats will be filled out during gnet_stats_copy_* calls 76and appended to the skb. TCA_XSTATS is provided if gnet_stats_copy_app 77was called. 78 79 80Locking: 81-------- 82 83Locks are taken before writing and released once all statistics have 84been written. Locks are always released in case of an error. You 85are responsible for making sure that the lock is initialized. 86 87 88Rate Estimator: 89--------------- 90 910) Prepare an estimator attribute. Most likely this would be in user 92 space. The value of this TLV should contain a tc_estimator structure. 93 As usual, such a TLV needs to be 32 bit aligned and therefore the 94 length needs to be appropriately set, etc. The estimator interval 95 and ewma log need to be converted to the appropriate values. 96 tc_estimator.c::tc_setup_estimator() is advisable to be used as the 97 conversion routine. It does a few clever things. It takes a time 98 interval in microsecs, a time constant also in microsecs and a struct 99 tc_estimator to be populated. The returned tc_estimator can be 100 transported to the kernel. Transfer such a structure in a TLV of type 101 TCA_RATE to your code in the kernel. 102 103In the kernel when setting up: 104 1051) make sure you have basic stats and rate stats setup first. 1062) make sure you have initialized stats lock that is used to setup such 107 stats. 1083) Now initialize a new estimator:: 109 110 int ret = gen_new_estimator(my_basicstats,my_rate_est_stats, 111 mystats_lock, attr_with_tcestimator_struct); 112 113 if ret == 0 114 success 115 else 116 failed 117 118From now on, every time you dump my_rate_est_stats it will contain 119up-to-date info. 120 121Once you are done, call gen_kill_estimator(my_basicstats, 122my_rate_est_stats) Make sure that my_basicstats and my_rate_est_stats 123are still valid (i.e still exist) at the time of making this call. 124 125 126Authors: 127-------- 128- Thomas Graf <tgraf@suug.ch> 129- Jamal Hadi Salim <hadi@cyberus.ca>