{"action":"created","issue":{"url":"https://api.github.com/repos/iovisor/bcc/issues/437","repository_url":"https://api.github.com/repos/iovisor/bcc","labels_url":"https://api.github.com/repos/iovisor/bcc/issues/437/labels{/name}","comments_url":"https://api.github.com/repos/iovisor/bcc/issues/437/comments","events_url":"https://api.github.com/repos/iovisor/bcc/issues/437/events","html_url":"https://github.com/iovisor/bcc/issues/437","id":141134415,"number":437,"title":"offwaketime userspace stack","user":{"login":"ceeaspb","id":7397675,"avatar_url":"https://avatars.githubusercontent.com/u/7397675?v=3","gravatar_id":"","url":"https://api.github.com/users/ceeaspb","html_url":"https://github.com/ceeaspb","followers_url":"https://api.github.com/users/ceeaspb/followers","following_url":"https://api.github.com/users/ceeaspb/following{/other_user}","gists_url":"https://api.github.com/users/ceeaspb/gists{/gist_id}","starred_url":"https://api.github.com/users/ceeaspb/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/ceeaspb/subscriptions","organizations_url":"https://api.github.com/users/ceeaspb/orgs","repos_url":"https://api.github.com/users/ceeaspb/repos","events_url":"https://api.github.com/users/ceeaspb/events{/privacy}","received_events_url":"https://api.github.com/users/ceeaspb/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":1,"created_at":"2016-03-16T00:18:46Z","updated_at":"2016-03-16T00:36:12Z","closed_at":null,"body":"Would it be possible to get the userspace stack? \r\neg. I can't see where these calls are coming from in the java runtime. \r\n\r\n```\r\n    waker:           java\r\n    ffffffff8181c832 entry_SYSCALL_64_fastpath\r\n    ffffffff81101861 sys_futex\r\n    ffffffff8110162e do_futex\r\n    ffffffff810ffa2c futex_wake_op\r\n    -                -\r\n    ffffffff81818755 schedule\r\n    ffffffff810fe902 futex_wait_queue_me\r\n    ffffffff810fec16 futex_wait\r\n    ffffffff81101400 do_futex\r\n    ffffffff81101861 sys_futex\r\n    ffffffff8181c832 entry_SYSCALL_64_fastpath\r\n    target:          java\r\n        19974615\r\n```"},"comment":{"url":"https://api.github.com/repos/iovisor/bcc/issues/comments/197085767","html_url":"https://github.com/iovisor/bcc/issues/437#issuecomment-197085767","issue_url":"https://api.github.com/repos/iovisor/bcc/issues/437","id":197085767,"user":{"login":"brendangregg","id":1101211,"avatar_url":"https://avatars.githubusercontent.com/u/1101211?v=3","gravatar_id":"","url":"https://api.github.com/users/brendangregg","html_url":"https://github.com/brendangregg","followers_url":"https://api.github.com/users/brendangregg/followers","following_url":"https://api.github.com/users/brendangregg/following{/other_user}","gists_url":"https://api.github.com/users/brendangregg/gists{/gist_id}","starred_url":"https://api.github.com/users/brendangregg/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/brendangregg/subscriptions","organizations_url":"https://api.github.com/users/brendangregg/orgs","repos_url":"https://api.github.com/users/brendangregg/repos","events_url":"https://api.github.com/users/brendangregg/events{/privacy}","received_events_url":"https://api.github.com/users/brendangregg/received_events","type":"User","site_admin":false},"created_at":"2016-03-16T00:36:12Z","updated_at":"2016-03-16T00:36:12Z","body":"Soon; this functionality should come with #231 , which also means kernel support and a newer kernel. @4ast has already coded it (stackmap) which made it into net-next, and hopefully the kernel very soon. So that will probably mean 4.6.\r\n\r\nThe trick here is that we're in kernel context with kernel regs, but we want to start walking the user-level frame pointer. So BPF needs task_pt_regs() or an equivalent. Anyway, it's coming.\r\n\r\nAs for the use case -- yes, I've seen this exact Java futex() stack, and want the Java methods to see which lock it is. :)"}}