{"action":"closed","issue":{"url":"https://api.github.com/repos/pandegroup/openmm/issues/1502","repository_url":"https://api.github.com/repos/pandegroup/openmm","labels_url":"https://api.github.com/repos/pandegroup/openmm/issues/1502/labels{/name}","comments_url":"https://api.github.com/repos/pandegroup/openmm/issues/1502/comments","events_url":"https://api.github.com/repos/pandegroup/openmm/issues/1502/events","html_url":"https://github.com/pandegroup/openmm/issues/1502","id":157106773,"number":1502,"title":"Massive GB performance regressions between 6.2 and 6.3","user":{"login":"jlmaccal","id":108119,"avatar_url":"https://avatars.githubusercontent.com/u/108119?v=3","gravatar_id":"","url":"https://api.github.com/users/jlmaccal","html_url":"https://github.com/jlmaccal","followers_url":"https://api.github.com/users/jlmaccal/followers","following_url":"https://api.github.com/users/jlmaccal/following{/other_user}","gists_url":"https://api.github.com/users/jlmaccal/gists{/gist_id}","starred_url":"https://api.github.com/users/jlmaccal/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/jlmaccal/subscriptions","organizations_url":"https://api.github.com/users/jlmaccal/orgs","repos_url":"https://api.github.com/users/jlmaccal/repos","events_url":"https://api.github.com/users/jlmaccal/events{/privacy}","received_events_url":"https://api.github.com/users/jlmaccal/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/pandegroup/openmm/labels/bug","name":"bug","color":"fc2929"}],"state":"closed","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":33,"created_at":"2016-05-27T00:26:26Z","updated_at":"2016-08-05T22:28:18Z","closed_at":"2016-08-05T22:28:18Z","body":"We have largely been using older versions of OpenMM with MELD, so we didn't catch this sooner.  There were **MASSIVE** performance decreases for GB simulations between 6.2 and 6.3, that persist up to the current master.\r\n\r\nRunning the test system below results in 200 ns / day with OpenMM 6.2. Running the same system with 6.3 or later results in **31 ns / day!**\r\n\r\nThe test system is here:\r\n<https://gist.github.com/ca6b08a307800f80986661075c82c432>\r\n\r\nResults are from ubuntu 14.04 with cuda 7.5.\r\nNVIDIA GTX 780\r\nCUDA 7.5\r\n\r\nWe expect similar results with Tesla 2070. I don't yet have access to newer GPUs for testing.\r\n\r\nI've spent the last few hours with `git bisect` and have identified the following culprits. Some appear to be related to changes @peastman made to implment triclinic boxes. Some appear specific to changes @swails made to gbNeck models.\r\n\r\nCommit | Description | Speed change (ns/day)\r\n-----------|-----------------|--------------------------------\r\n61458a5 | Beginning of CUDA support for triclinic boxes | 200 to 158\r\n6eb302f | Continuing to implement CUDA support for triclinic boxes | 158 to 136\r\ndafd0f9 | GBn now uses Discrete2DFunctions | 136 to 141 (this is slightly faster)\r\n4c450bf | Move to using a continuous 2D function. | 141 to 31"}}
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