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Performance regression across all 4 build variants for single threaded performance on Mongo-Perf. Slightly more pronounced on 1 node repl set over stand-alone, but present in both cases. Update.MmsIncShallow1 is the largest offender. Regression seems to be over time. Between 3.0.6, and 3.1.0, 3.1.3, and 3.1.4. Regression in WiredTiger Standalone (cumulative 11-13% degradation) and in MMAP (cumulative 13-17% degradation). Can be reproduced with var setupMMS = function( collection ) { collection.drop(); var base = { _id: 0, a: 0, h: {}, z: 0 }; for (var i = 0; i < 24; i++) { base.h[i] = {}; for (var j = 0; j < 60; j++) { base.h[i][j] = { n: 0, t: 0, v: 0 }; } } collection.insert(base); }; use test0 setupMMS(db.Update_MmsIncShallow10) benchRun({"ops":[{"op":"update","query":{"_id":0},"update":{"$inc":{"a":1}},"ns":"test0.Update_MmsIncShallow10","safe":false,"w":0,"j":false,"writeCmd":true}],"seconds":5,"host":"127.0.0.1:27017","parallel":1})

Top User Comments

craig.homa commented on Mon, 5 Aug 2019 15:41:41 +0000: Closing as future perf work should be based on a broad view of system perf instead of targeting old reports of perf regressions. eddie.louie commented on Wed, 6 Sep 2017 17:46:23 +0000: This seems like a very old ticket. Should we close this? david.daly commented on Mon, 30 Nov 2015 16:44:19 +0000: This has gotten a couple percent faster (8% regression) since this ticket was filed, but still worth investigating. Here are more recent WT results xgen-internal-githook commented on Tue, 27 Oct 2015 17:45:57 +0000: Author: {u'username': u'ksuarz', u'name': u'Kyle Suarez', u'email': u'ksuarz@gmail.com'} Message: SERVER-20786 overrides for singleThreaded Closes #1040 Signed-off-by: dalyd Branch: master https://github.com/mongodb/mongo/commit/70a6c8b04b1b3250db7b4a982217ec9a7d4e1e15 xgen-internal-githook commented on Thu, 22 Oct 2015 13:48:52 +0000: Author: {u'username': u'dalyd', u'name': u'David', u'email': u'david.daly@mongodb.com'} Message: Merge pull request #1032 from ksuarz/master SERVER-20786 override singleThreaded regression Branch: master https://github.com/mongodb/mongo/commit/30efc2300ad8740023ebb432723a1e662d16ef89 xgen-internal-githook commented on Thu, 22 Oct 2015 13:48:51 +0000: Author: {u'username': u'ksuarz', u'name': u'Kyle Suarez', u'email': u'ksuarz@gmail.com'} Message: SERVER-20786 override singleThreaded regression Branch: master https://github.com/mongodb/mongo/commit/46690d94e3f1350788226c2af3ecbb92020cc351 martin.bligh commented on Thu, 8 Oct 2015 21:16:30 +0000: OK, I backed out some logging changes I had in my dev view - now I get 27500 ops/s with either 3.0.6 or master. martin.bligh commented on Thu, 8 Oct 2015 20:27:00 +0000: Oops. Previous seems to be bleed-through from something else, not sure how perf attributed it to mongod. Old profile: + 2.49% mongod mongod [.] operator new(unsigned long) � + 2.14% mongod mongod [.] mongo::validateBSON(char const*, unsigned long) � + 1.73% mongod libpthread-2.19.so [.] pthread_spin_trylock � + 1.68% mongod mongod [.] operator delete(void*) � + 1.42% mongod [vdso] [.] 0x0000000000000f08 � + 1.04% mongod [kernel.kallsyms] [k] _raw_spin_lock_irqsave � + 1.02% mongod mongod [.] mongo::BSONElement::size() const Sometimes (on new version) I get __log_wrlsn_server traffic, sometimes I don't - 5.23% mongod [kernel.kallsyms] [k] update_blocked_averages � - update_blocked_averages � - 97.55% idle_balance � __schedule � - schedule � + 51.64% schedule_hrtimeout_range_clock � - 48.36% futex_wait_queue_me � futex_wait � do_futex � sys_futex � system_call_fastpath � - pthread_cond_timedwait@@GLIBC_2.3.2 � + 94.81% __log_wrlsn_server � + 5.19% __log_server � + 2.45% __schedule � + 4.67% mongod mongod [.] __wt_log_wrlsn � + 3.83% mongod [kernel.kallsyms] [k] update_cfs_rq_blocked_load � + 3.78% mongod libc-2.19.so [.] __clock_gettime � + 3.44% mongod [kernel.kallsyms] [k] futex_wait_queue_me � + 3.44% mongod [kernel.kallsyms] [k] futex_wait_setup � + 3.03% mongod [kernel.kallsyms] [k] update_curr � + 2.61% mongod [vdso] [.] 0x0000000000000802 Sometimes I get this too (FTDC) - 4.90% mongod mongod [.] mongo::MetricTree::appendTo(mongo::BSONObjBuilder&) cons� - mongo::MetricTree::appendTo(mongo::BSONObjBuilder&) const � - mongo::MetricTree::appendTo(mongo::BSONObjBuilder&) const � - 78.34% mongo::MetricTree::appendTo(mongo::BSONObjBuilder&) const � - 56.87% mongo::CmdServerStatus::run(mongo::OperationContext*, std::string const&, mongo::� mongo::(anonymous namespace)::FTDCSimpleInternalCommandCollector::collect(mongo::Oper� mongo::FTDCCollectorCollection::collect(mongo::Client*) � mongo::FTDCController::doLoop() � execute_native_thread_routine � + 43.13% mongo::MetricTree::appendTo(mongo::BSONObjBuilder&) const � + 21.66% mongo::CmdServerStatus::run(mongo::OperationContext*, std::string const&, mongo::BSO� david.daly commented on Tue, 6 Oct 2015 15:32:15 +0000: I did some profiling comparing between 3.1.0 and a recent master. The largest differences I was able to pull out were malloc related. new delete tcmalloc

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