Hello, Posting v3 (not final yet). New patch 5 just for debugging, do not apply if not needed. This patchset implements stats estimation in kthread context. Simple tests do not show any problem. Overview of the basic concepts. More in the commit messages... RCU Locking: - As stats are now RCU-locked, tot_stats, svc and dest which hold estimator structures are now always freed from RCU callback. This ensures RCU grace period after the ip_vs_stop_estimator() call. Kthread data: - every kthread works over its own data structure and all such structures are attached to array - even while there can be a kthread structure, its task may not be running, eg. before first service is added or while the sysctl var is set to an empty cpulist or when run_estimation is 0. - a task and its structure may be released if all estimators are unlinked from its chains, leaving the slot in the array empty - every kthread data structure allows limited number of estimators - to add new estimators we use the last added kthread context (est_add_ktid). The new estimators are linked to the chains just before the estimated one, based on add_row. This ensures their estimation will start after 2 seconds. If estimators are added in bursts, common case if all services and dests are initially configured, we may spread the estimators to more chains. This will reduce the chain imbalance. Not done yet: * start kthread to calculate chain_max_len and IPVS_EST_TICK_CHAINS suitable for 100us cond_resched rate and 10% of 40ms. Current value of IPVS_EST_TICK_CHAINS=48 determines tick time of 4.8ms (i.e. in units of 100us) which is 12% of max tick time of 40ms. The question is how valid will be such test. For example, we can add all ests in temp list until the calculation is done and then to requeue all estimators into the chains. Changes in v3: * calculate chain_max_len (was IPVS_EST_CHAIN_DEPTH) but it needs further tuning based on real estimation test * est_max_threads set from rlimit(RLIMIT_NPROC). I don't see analog to get_ucounts_value() to get the max value. * the atomic bitop for td->present is not needed, remove it * start filling based on est_row after 2 ticks are fully allocated. As 2/50 is 4% this can be increased more. Changes in v2: Patch 2: * kd->mutex is gone, cond_resched rate determined by IPVS_EST_CHAIN_DEPTH * IPVS_EST_MAX_COUNT is a hard limit now * kthread data is now 1-50 allocated tick structures, each containing heads for limited chains. Bitmaps should allow faster access. We avoid large allocations for structs. * as the td->present bitmap is shared, use atomic bitops * ip_vs_start_estimator now returns error code * _bh locking removed from stats->lock * bump arg is gone from ip_vs_est_reload_start * prepare for upcoming changes that remove _irq from u64_stats_fetch_begin_irq/u64_stats_fetch_retry_irq * est_add_ktid is now always valid Patch 3: * use .. in est_nice docs Julian Anastasov (5): ipvs: add rcu protection to stats ipvs: use kthreads for stats estimation ipvs: add est_cpulist and est_nice sysctl vars ipvs: run_estimation should control the kthread tasks ipvs: debug the tick time Documentation/networking/ipvs-sysctl.rst | 24 +- include/net/ip_vs.h | 125 +++++- net/netfilter/ipvs/ip_vs_core.c | 10 +- net/netfilter/ipvs/ip_vs_ctl.c | 367 ++++++++++++++--- net/netfilter/ipvs/ip_vs_est.c | 487 +++++++++++++++++++---- 5 files changed, 883 insertions(+), 130 deletions(-) -- 2.37.3
