On Fri, Dec 04, 2020 at 07:42:56AM +0200, Julian Anastasov wrote: > > Hello, > >On Fri, 4 Dec 2020, dust.li wrote: > >> >> On 12/3/20 4:48 PM, Julian Anastasov wrote: >> > >> > - work will use spin_lock_bh(&s->lock) to protect the >> > entries, we do not want delays between /proc readers and >> > the work if using mutex. But _bh locks stop timers and >> > networking for short time :( Not sure yet if just spin_lock >> > is safe for both /proc and estimator's work. > > Here stopping BH is may be not so fatal if some >CPUs are used for networking and others for workqueues. > >> Thanks for sharing your thoughts ! >> >> >> I think it's a good idea to split the est_list into different >> >> slots, I believe it will dramatically reduce the delay brought >> >> by estimation. > > 268ms/64 => 4ms average. As the estimation with single >work does not utilize many CPUs simultaneously, this can be a >problem for 300000-400000 services but this looks crazy. Yes. Consider the largest server we use now, which has 256 HT servers with 4 NUMA nodes. Even that should not be a big problem. > >> My only concern is the cost of the estimation when the number of >> >> services is large. Splitting the est_list won't reduce the real >> >> work to do. >> >> In our case, each estimation cost at most 268ms/2000ms, which is >> >> about 13% of one CPU hyper-thread, and this should be a common case >> >> in a large K8S cluster with lots of services. >> >> Since the estimation is not needed in our environment at all, it's >> >> just a waste of CPU resource. Have you ever consider add a switch to >> >> let the user turn the estimator off ? > > No problem to add sysctl var for this, we usually add function >to check which can be used in ip_vs_in_stats, ip_vs_out_stats, >ip_vs_conn_stats. If switch can be changed at any time, what should >we do? Add/Del est entries as normally but do not start the >delayed work if flag disables stats. When flag is enabled counters >will increase and we will start delayed work. Yes, this would be perfect for me !
