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129 lines
3.9 KiB
129 lines
3.9 KiB
.. SPDX-License-Identifier: GPL-2.0 |
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=============================================== |
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Generic networking statistics for netlink users |
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=============================================== |
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Statistic counters are grouped into structs: |
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==================== ===================== ===================== |
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Struct TLV type Description |
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==================== ===================== ===================== |
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gnet_stats_basic TCA_STATS_BASIC Basic statistics |
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gnet_stats_rate_est TCA_STATS_RATE_EST Rate estimator |
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gnet_stats_queue TCA_STATS_QUEUE Queue statistics |
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none TCA_STATS_APP Application specific |
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==================== ===================== ===================== |
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Collecting: |
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----------- |
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Declare the statistic structs you need:: |
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struct mystruct { |
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struct gnet_stats_basic bstats; |
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struct gnet_stats_queue qstats; |
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... |
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}; |
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Update statistics, in dequeue() methods only, (while owning qdisc->running):: |
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mystruct->tstats.packet++; |
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mystruct->qstats.backlog += skb->pkt_len; |
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Export to userspace (Dump): |
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--------------------------- |
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:: |
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my_dumping_routine(struct sk_buff *skb, ...) |
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{ |
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struct gnet_dump dump; |
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if (gnet_stats_start_copy(skb, TCA_STATS2, &mystruct->lock, &dump, |
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TCA_PAD) < 0) |
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goto rtattr_failure; |
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if (gnet_stats_copy_basic(&dump, &mystruct->bstats) < 0 || |
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gnet_stats_copy_queue(&dump, &mystruct->qstats) < 0 || |
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gnet_stats_copy_app(&dump, &xstats, sizeof(xstats)) < 0) |
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goto rtattr_failure; |
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if (gnet_stats_finish_copy(&dump) < 0) |
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goto rtattr_failure; |
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... |
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} |
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TCA_STATS/TCA_XSTATS backward compatibility: |
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-------------------------------------------- |
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Prior users of struct tc_stats and xstats can maintain backward |
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compatibility by calling the compat wrappers to keep providing the |
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existing TLV types:: |
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my_dumping_routine(struct sk_buff *skb, ...) |
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{ |
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if (gnet_stats_start_copy_compat(skb, TCA_STATS2, TCA_STATS, |
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TCA_XSTATS, &mystruct->lock, &dump, |
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TCA_PAD) < 0) |
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goto rtattr_failure; |
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... |
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} |
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A struct tc_stats will be filled out during gnet_stats_copy_* calls |
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and appended to the skb. TCA_XSTATS is provided if gnet_stats_copy_app |
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was called. |
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Locking: |
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-------- |
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Locks are taken before writing and released once all statistics have |
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been written. Locks are always released in case of an error. You |
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are responsible for making sure that the lock is initialized. |
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Rate Estimator: |
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--------------- |
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0) Prepare an estimator attribute. Most likely this would be in user |
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space. The value of this TLV should contain a tc_estimator structure. |
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As usual, such a TLV needs to be 32 bit aligned and therefore the |
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length needs to be appropriately set, etc. The estimator interval |
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and ewma log need to be converted to the appropriate values. |
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tc_estimator.c::tc_setup_estimator() is advisable to be used as the |
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conversion routine. It does a few clever things. It takes a time |
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interval in microsecs, a time constant also in microsecs and a struct |
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tc_estimator to be populated. The returned tc_estimator can be |
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transported to the kernel. Transfer such a structure in a TLV of type |
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TCA_RATE to your code in the kernel. |
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In the kernel when setting up: |
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1) make sure you have basic stats and rate stats setup first. |
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2) make sure you have initialized stats lock that is used to setup such |
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stats. |
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3) Now initialize a new estimator:: |
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int ret = gen_new_estimator(my_basicstats,my_rate_est_stats, |
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mystats_lock, attr_with_tcestimator_struct); |
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if ret == 0 |
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success |
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else |
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failed |
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From now on, every time you dump my_rate_est_stats it will contain |
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up-to-date info. |
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Once you are done, call gen_kill_estimator(my_basicstats, |
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my_rate_est_stats) Make sure that my_basicstats and my_rate_est_stats |
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are still valid (i.e still exist) at the time of making this call. |
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Authors: |
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-------- |
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- Thomas Graf <[email protected]> |
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- Jamal Hadi Salim <[email protected]>
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