{"action":"created","issue":{"url":"https://api.github.com/repos/gcp/leela-zero/issues/901","repository_url":"https://api.github.com/repos/gcp/leela-zero","labels_url":"https://api.github.com/repos/gcp/leela-zero/issues/901/labels{/name}","comments_url":"https://api.github.com/repos/gcp/leela-zero/issues/901/comments","events_url":"https://api.github.com/repos/gcp/leela-zero/issues/901/events","html_url":"https://github.com/gcp/leela-zero/issues/901","id":299135540,"number":901,"title":"Multi GPU scalibility","user":{"login":"bjiyxo","id":30645842,"avatar_url":"https://avatars2.githubusercontent.com/u/30645842?v=4","gravatar_id":"","url":"https://api.github.com/users/bjiyxo","html_url":"https://github.com/bjiyxo","followers_url":"https://api.github.com/users/bjiyxo/followers","following_url":"https://api.github.com/users/bjiyxo/following{/other_user}","gists_url":"https://api.github.com/users/bjiyxo/gists{/gist_id}","starred_url":"https://api.github.com/users/bjiyxo/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/bjiyxo/subscriptions","organizations_url":"https://api.github.com/users/bjiyxo/orgs","repos_url":"https://api.github.com/users/bjiyxo/repos","events_url":"https://api.github.com/users/bjiyxo/events{/privacy}","received_events_url":"https://api.github.com/users/bjiyxo/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":12,"created_at":"2018-02-21T21:29:47Z","updated_at":"2018-02-23T14:47:32Z","closed_at":null,"author_association":"NONE","body":"I'm testing the scalibility of 2 GPUs. The results are tested under 7900X(without hyper-threading) & 2 1080Ti and the OS is Ubuntu 17.10. Here are the results.\r\n\r\n1GPU \r\nthreads            2       | 3       | 4\r\n1st  move(n/s) 3941 | 4792 | 3239\r\n2nd move(n/s) 3343 | 4184 | 2819\r\n\r\n2GPUs\r\nthreads            4       | 5       | 6       | 7       | 8      | 9       | 10\r\n1st  move(n/s) 3410 | 3832 | 5186 | 5630 | 6611 | 6692 | 6827\r\n2nd move(n/s) 2961 | 3258 | 4137 | 4668 | 5721 | 5867 | 5747\r\n\r\nIt looks like the speed is close over 8 threads, so I tested it twice.\r\n2GPUs\r\nthreads            8       | 9       | 10\r\n1st  move(n/s) 6668 | 6889 | 7093\r\n2nd move(n/s) 5953 | 6010 | 6244\r\n\r\nSo is there any optimization problems in 2GPUs system?\r\n\r\nPS:\r\nUsing x thread(s). is broken when x >= 10."},"comment":{"url":"https://api.github.com/repos/gcp/leela-zero/issues/comments/368029137","html_url":"https://github.com/gcp/leela-zero/issues/901#issuecomment-368029137","issue_url":"https://api.github.com/repos/gcp/leela-zero/issues/901","id":368029137,"user":{"login":"ihavnoid","id":33939814,"avatar_url":"https://avatars3.githubusercontent.com/u/33939814?v=4","gravatar_id":"","url":"https://api.github.com/users/ihavnoid","html_url":"https://github.com/ihavnoid","followers_url":"https://api.github.com/users/ihavnoid/followers","following_url":"https://api.github.com/users/ihavnoid/following{/other_user}","gists_url":"https://api.github.com/users/ihavnoid/gists{/gist_id}","starred_url":"https://api.github.com/users/ihavnoid/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/ihavnoid/subscriptions","organizations_url":"https://api.github.com/users/ihavnoid/orgs","repos_url":"https://api.github.com/users/ihavnoid/repos","events_url":"https://api.github.com/users/ihavnoid/events{/privacy}","received_events_url":"https://api.github.com/users/ihavnoid/received_events","type":"User","site_admin":false},"created_at":"2018-02-23T14:47:32Z","updated_at":"2018-02-23T14:47:32Z","author_association":"CONTRIBUTOR","body":"To comment on the scalability - Your observation seems to be similar to what I observed while writing the initial multi-GPU code.  The more powerful the GPU is, the more threads it takes to exploit the full potential of the GPU.  I won't go into too much detail here, but it has to do with thread synchronization overhead and OpenCL stack overhead.  The anticipation was that the overhead will turn into a smaller portion as we move to bigger networks.\r\n\r\nI think there are some other optimizations that can be made but since I don't have two 1080ti GPUs I can't really tweak the thread implementation for your specific setup."}}
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