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-Generic networking statistics for netlink users
-======================================================================
-
-Statistic counters are grouped into structs:
-
-Struct TLV type Description
-----------------------------------------------------------------------
-gnet_stats_basic TCA_STATS_BASIC Basic statistics
-gnet_stats_rate_est TCA_STATS_RATE_EST Rate estimator
-gnet_stats_queue TCA_STATS_QUEUE Queue statistics
-none TCA_STATS_APP Application specific
-
-
-Collecting:
------------
-
-Declare the statistic structs you need:
-struct mystruct {
- struct gnet_stats_basic bstats;
- struct gnet_stats_queue qstats;
- ...
-};
-
-Update statistics:
-mystruct->tstats.packet++;
-mystruct->qstats.backlog += skb->pkt_len;
-
-
-Export to userspace (Dump):
----------------------------
-
-my_dumping_routine(struct sk_buff *skb, ...)
-{
- struct gnet_dump dump;
-
- if (gnet_stats_start_copy(skb, TCA_STATS2, &mystruct->lock, &dump) < 0)
- goto rtattr_failure;
-
- if (gnet_stats_copy_basic(&dump, &mystruct->bstats) < 0 ||
- gnet_stats_copy_queue(&dump, &mystruct->qstats) < 0 ||
- gnet_stats_copy_app(&dump, &xstats, sizeof(xstats)) < 0)
- goto rtattr_failure;
-
- if (gnet_stats_finish_copy(&dump) < 0)
- goto rtattr_failure;
- ...
-}
-
-TCA_STATS/TCA_XSTATS backward compatibility:
---------------------------------------------
-
-Prior users of struct tc_stats and xstats can maintain backward
-compatibility by calling the compat wrappers to keep providing the
-existing TLV types.
-
-my_dumping_routine(struct sk_buff *skb, ...)
-{
- if (gnet_stats_start_copy_compat(skb, TCA_STATS2, TCA_STATS,
- TCA_XSTATS, &mystruct->lock, &dump) < 0)
- goto rtattr_failure;
- ...
-}
-
-A struct tc_stats will be filled out during gnet_stats_copy_* calls
-and appended to the skb. TCA_XSTATS is provided if gnet_stats_copy_app
-was called.
-
-
-Locking:
---------
-
-Locks are taken before writing and released once all statistics have
-been written. Locks are always released in case of an error. You
-are responsible for making sure that the lock is initialized.
-
-
-Rate Estimator:
---------------
-
-0) Prepare an estimator attribute. Most likely this would be in user
- space. The value of this TLV should contain a tc_estimator structure.
- As usual, such a TLV needs to be 32 bit aligned and therefore the
- length needs to be appropriately set, etc. The estimator interval
- and ewma log need to be converted to the appropriate values.
- tc_estimator.c::tc_setup_estimator() is advisable to be used as the
- conversion routine. It does a few clever things. It takes a time
- interval in microsecs, a time constant also in microsecs and a struct
- tc_estimator to be populated. The returned tc_estimator can be
- transported to the kernel. Transfer such a structure in a TLV of type
- TCA_RATE to your code in the kernel.
-
-In the kernel when setting up:
-1) make sure you have basic stats and rate stats setup first.
-2) make sure you have initialized stats lock that is used to setup such
- stats.
-3) Now initialize a new estimator:
-
- int ret = gen_new_estimator(my_basicstats,my_rate_est_stats,
- mystats_lock, attr_with_tcestimator_struct);
-
- if ret == 0
- success
- else
- failed
-
-From now on, every time you dump my_rate_est_stats it will contain
-up-to-date info.
-
-Once you are done, call gen_kill_estimator(my_basicstats,
-my_rate_est_stats) Make sure that my_basicstats and my_rate_est_stats
-are still valid (i.e still exist) at the time of making this call.
-
-
-Authors:
---------
-Thomas Graf <tgraf@suug.ch>
-Jamal Hadi Salim <hadi@cyberus.ca>