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  1. Core Server
  2. SERVER-17341

update on single doc is slower than 2.6 (both WT and mmapv1)

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Critical - P2
    • Resolution: Duplicate
    • Affects Version/s: 3.0.0-rc9
    • Fix Version/s: None
    • Component/s: Storage
    • Labels:
    • Operating System:
      ALL

      Description

      Test

      • standalone mongod
      • test with following benchRun script:

        var run = function() {
                var d = db.getSiblingDB("test");
                d.foo.insert({_id:1,a:0});
         
                res = benchRun( {
                        ops : [{
                                        ns : "test.foo",
                                        op : "update" ,
                                        query: {_id: 1},
                                        update : { $inc: {a: 1} } ,
                                        w: 1,
                                        writeCmd : true }],
                        seconds : 60,
                        totals : true,
                        writeCmd : true,
                        w: 1,
                        parallel : 40
                });
         
                return res
        }
         
        var s = db.serverStatus();
        var v = db.serverBuildInfo();
         
        print("Version: " + v.version)
        print("git version: " + v.gitVersion)
        if ( s.storageEngine !== undefined) {
            print("storageEngine: " + db.serverStatus().storageEngine.name)
        }
        print("Update RPS: " + run().update);

      Results:

      • the throughput from both WT and mmapv1 is slower than that of 2.6.7
        test rc9 + wt rc9 + mmapv1 2.6.7 + mmapv0
        contenedUpdate (update with 40 thread) 23082 22061 25975
        update with 1 thread 8947 10849 10816

      Observation

      • WT update is slow, this probably related how update is done with WT. With single thread update, it is 17.3% slower than 2.6.7, and 11.2% with 40 thread update
      • mmapv1 is slower when there is contention, and in par with mmapv0 (single thread update)

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                • Created:
                  Updated:
                  Resolved: