{"action":"opened","issue":{"url":"https://api.github.com/repos/BVLC/caffe/issues/4287","repository_url":"https://api.github.com/repos/BVLC/caffe","labels_url":"https://api.github.com/repos/BVLC/caffe/issues/4287/labels{/name}","comments_url":"https://api.github.com/repos/BVLC/caffe/issues/4287/comments","events_url":"https://api.github.com/repos/BVLC/caffe/issues/4287/events","html_url":"https://github.com/BVLC/caffe/issues/4287","id":159715075,"number":4287,"title":"Backward compatibility for NVIDIA GPUs (CUDA capability <= 2.x)","user":{"login":"cepiross","id":6228108,"avatar_url":"https://avatars.githubusercontent.com/u/6228108?v=3","gravatar_id":"","url":"https://api.github.com/users/cepiross","html_url":"https://github.com/cepiross","followers_url":"https://api.github.com/users/cepiross/followers","following_url":"https://api.github.com/users/cepiross/following{/other_user}","gists_url":"https://api.github.com/users/cepiross/gists{/gist_id}","starred_url":"https://api.github.com/users/cepiross/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/cepiross/subscriptions","organizations_url":"https://api.github.com/users/cepiross/orgs","repos_url":"https://api.github.com/users/cepiross/repos","events_url":"https://api.github.com/users/cepiross/events{/privacy}","received_events_url":"https://api.github.com/users/cepiross/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2016-06-10T20:21:28Z","updated_at":"2016-06-10T20:21:28Z","closed_at":null,"body":"Hi.\r\n\r\nWhile investigating source codes, I recognize that the current version cannot correctly support some NVIDIA GPUs, especially at CUDA capability <= 2.x, because of limitation of maximum grid blocks.\r\nAs stated in https://groups.google.com/forum/#!topic/caffe-users/DWsH35-6HWA, their maximum number of grid blocks is 65535.\r\n\r\nAn old pull request (https://github.com/BVLC/caffe/pull/727) tried to resolve this problem. However, unfortunately, since the pull request dealt with support of Windows at the same time, it was ignored.\r\n\r\nIn these days, the previous solution would not be exactly adapted because Caffe needs to support the usage of multiple GPUs. However, at least following items are inevitable:\r\n- Caffe instance should contain the maximum number of grid blocks for each GPU.\r\n- Whenever calling [CAFFE_GET_BLOCKS](https://github.com/BVLC/caffe/blob/master/include/caffe/util/device_alternate.hpp#L87-90), we need to compare the number of blocks for threads to the maximum number.\r\n\r\nEven though I would like to modify source codes following https://github.com/BVLC/caffe/pull/727 so as to create a pull request by myself, I do not exactly know where to start because of consideration of multiple GPUs. Would you mind to give me some advice? Otherwise, it is also okay if you can deal with this issue.\r\n\r\nThanks."}}
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