kernel/linux.git/net/core/gen_estimator.c, branch v4.9.331

net: sched: do not acquire qdisc spinlock in qdisc/class stats dump

2016-06-07T23:37:14+00:00

Large tc dumps (tc -s {qdisc|class} sh dev ethX) done by Google BwE host agent [1] are problematic at scale : For each qdisc/class found in the dump, we currently lock the root qdisc spinlock in order to get stats. Sampling stats every 5 seconds from thousands of HTB classes is a challenge when the root qdisc spinlock is under high pressure. Not only the dumps take time, they also slow down the fast path (queue/dequeue packets) by 10 % to 20 % in some cases. An audit of existing qdiscs showed that sch_fq_codel is the only qdisc that might need the qdisc lock in fq_codel_dump_stats() and fq_codel_dump_class_stats() In v2 of this patch, I now use the Qdisc running seqcount to provide consistent reads of packets/bytes counters, regardless of 32/64 bit arches. I also changed rate estimators to use the same infrastructure so that they no longer need to lock root qdisc lock. [1] http://static.googleusercontent.com/media/research.google.com/en//pubs/archive/43838.pdf Signed-off-by: Eric Dumazet Cc: Cong Wang Cc: Jamal Hadi Salim Cc: John Fastabend Cc: Kevin Athey Cc: Xiaotian Pei Signed-off-by: David S. Miller

net: sched: Add description for cpu_bstats argument

2016-03-20T20:48:07+00:00

Commit 22e0f8b9322c ("net: sched: make bstats per cpu and estimator RCU safe") added the argument cpu_bstats to functions gen_new_estimator and gen_replace_estimator and now the descriptions of these are missing for the documentation. Adding them. Signed-off-by: Luis de Bethencourt Signed-off-by: David S. Miller

net_sched: gen_estimator: extend pps limit

2015-07-08T20:59:20+00:00

rate estimators are limited to 4 Mpps, which was fine years ago, but too small with current hardware generation. Lets use 2^5 scaling instead of 2^10 to get 128 Mpps new limit. On 64bit arch, use an "unsigned long" for temp storage and remove limit. (We do not expect 32bit arches to be able to reach this point) Tested: tc -s -d filter sh dev eth0 parent ffff: filter protocol ip pref 1 u32 filter protocol ip pref 1 u32 fh 800: ht divisor 1 filter protocol ip pref 1 u32 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:15 match 07000000/ff000000 at 12 action order 1: gact action drop random type none pass val 0 index 1 ref 1 bind 1 installed 166 sec Action statistics: Sent 39734251496 bytes 863788076 pkt (dropped 863788117, overlimits 0 requeues 0) rate 4067Mbit 11053596pps backlog 0b 0p requeues 0 Signed-off-by: Eric Dumazet Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller

net: sched: make bstats per cpu and estimator RCU safe

2014-09-30T05:02:26+00:00

In order to run qdisc's without locking statistics and estimators need to be handled correctly. To resolve bstats make the statistics per cpu. And because this is only needed for qdiscs that are running without locks which is not the case for most qdiscs in the near future only create percpu stats when qdiscs set the TCQ_F_CPUSTATS flag. Next because estimators use the bstats to calculate packets per second and bytes per second the estimator code paths are updated to use the per cpu statistics. Signed-off-by: John Fastabend Signed-off-by: David S. Miller

net: treewide: Fix typo found in DocBook/networking.xml

2014-09-06T00:35:28+00:00

This patch fix spelling typo found in DocBook/networking.xml. It is because the neworking.xml is generated from comments in the source, I have to fix typo in comments within the source. Signed-off-by: Masanari Iida Acked-by: Randy Dunlap Signed-off-by: David S. Miller

net_sched: add 64bit rate estimators

2013-06-11T09:51:03+00:00

struct gnet_stats_rate_est contains u32 fields, so the bytes per second field can wrap at 34360Mbit. Add a new gnet_stats_rate_est64 structure to get 64bit bps/pps fields, and switch the kernel to use this structure natively. This structure is dumped to user space as a new attribute : TCA_STATS_RATE_EST64 Old tc command will now display the capped bps (to 34360Mbit), instead of wrapped values, and updated tc command will display correct information. Old tc command output, after patch : eric:~# tc -s -d qd sh dev lo qdisc pfifo 8001: root refcnt 2 limit 1000p Sent 80868245400 bytes 1978837 pkt (dropped 0, overlimits 0 requeues 0) rate 34360Mbit 189696pps backlog 0b 0p requeues 0 This patch carefully reorganizes "struct Qdisc" layout to get optimal performance on SMP. Signed-off-by: Eric Dumazet Cc: Ben Hutchings Signed-off-by: David S. Miller

Remove all #inclusions of asm/system.h

2012-03-28T17:30:03+00:00

Remove all #inclusions of asm/system.h preparatory to splitting and killing it. Performed with the following command: perl -p -i -e 's!^#\s*include\s*.*\n!!' `grep -Irl '^#\s*include\s*' *` Signed-off-by: David Howells

net,rcu: convert call_rcu(__gen_kill_estimator) to kfree_rcu()

2011-05-08T05:50:57+00:00

The rcu callback __gen_kill_estimator() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(__gen_kill_estimator). Signed-off-by: Lai Jiangshan Acked-by: David S. Miller Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett

pkt_sched: remov unnecessary bh_disable

2010-09-10T19:47:59+00:00

Now that est_tree_lock is acquired with BH protection, the other call is unnecessary. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller

pkt_sched: Fix lockdep warning on est_tree_lock in gen_estimator

2010-09-02T20:22:11+00:00

This patch fixes a lockdep warning: [ 516.287584] ========================================================= [ 516.288386] [ INFO: possible irq lock inversion dependency detected ] [ 516.288386] 2.6.35b #7 [ 516.288386] --------------------------------------------------------- [ 516.288386] swapper/0 just changed the state of lock: [ 516.288386] (&qdisc_tx_lock){+.-...}, at: [] est_timer+0x62/0x1b4 [ 516.288386] but this lock took another, SOFTIRQ-unsafe lock in the past: [ 516.288386] (est_tree_lock){+.+...} [ 516.288386] [ 516.288386] and interrupts could create inverse lock ordering between them. ... So, est_tree_lock needs BH protection because it's taken by qdisc_tx_lock, which is used both in BH and process contexts. (Full warning with this patch at netdev, 02 Sep 2010.) Fixes commit: ae638c47dc040b8def16d05dc6acdd527628f231 ("pkt_sched: gen_estimator: add a new lock") Signed-off-by: Jarek Poplawski Signed-off-by: David S. Miller