GitHub pull request #2660 of commit c5de947040288922a8b1c9d73766029a485099ce, no merge conflicts.sha1origin/pr/2660/mergeghprbActualCommitc5de947040288922a8b1c9d73766029a485099ceghprbActualCommitAuthorghprbActualCommitAuthorEmailghprbAuthorRepoGitUrlhttps://github.com/piterpunk/bcc.gitghprbTriggerAuthorghprbTriggerAuthorEmailghprbTriggerAuthorLoginyonghong-songghprbTriggerAuthorLoginMention@yonghong-songghprbPullId2660ghprbTargetBranchmasterghprbSourceBranchmasterGIT_BRANCHmasterghprbPullAuthorEmailghprbPullAuthorLoginpiterpunkghprbPullAuthorLoginMention@piterpunkghprbPullDescriptionGitHub pull request #2660 of commit c5de947040288922a8b1c9d73766029a485099ce, no merge conflicts.ghprbPullTitleFix time going backwards on biolatency and biotopghprbPullLinkhttps://github.com/iovisor/bcc/pull/2660ghprbPullLongDescriptionSometimes the time collected in the request completion is older than the one collected in the request start. This results in enormous numbers in the measured latency. The wrong latency makes histograms from biolatency occupies a lot of screen lines and the shows very high (and impossible) numbers on biotop.\r\n\r\nThis fix adds a check if signed delta is a negative number, in this case, the time of request completion is older than the request start and the offensor request is discarded.\r\n\r\nThis is the biolatency output before this change:\r\n\r\n```\r\nTracing block device I/O... Hit Ctrl-C to end.\r\n^C\r\n usecs : count distribution\r\n 0 -> 1 : 0 | |\r\n 2 -> 3 : 0 | |\r\n 4 -> 7 : 0 | |\r\n 8 -> 15 : 0 | |\r\n 16 -> 31 : 25 | |\r\n 32 -> 63 : 32 | |\r\n 64 -> 127 : 254 | |\r\n 128 -> 255 : 2164 |* |\r\n 256 -> 511 : 5421 |*** |\r\n 512 -> 1023 : 29795 |********************|\r\n 1024 -> 2047 : 17042 |*********** |\r\n 2048 -> 4095 : 6400 |**** |\r\n 4096 -> 8191 : 4935 |*** |\r\n 8192 -> 16383 : 588 | |\r\n 16384 -> 32767 : 54 | |\r\n 32768 -> 65535 : 14 | |\r\n 65536 -> 131071 : 4 | |\r\n 131072 -> 262143 : 4 | |\r\n 262144 -> 524287 : 0 | |\r\n 524288 -> 1048575 : 0 | |\r\n 1048576 -> 2097151 : 0 | |\r\n 2097152 -> 4194303 : 0 | |\r\n 4194304 -> 8388607 : 0 | |\r\n 8388608 -> 16777215 : 0 | |\r\n 16777216 -> 33554431 : 0 | |\r\n 33554432 -> 67108863 : 0 | |\r\n 67108864 -> 134217727 : 0 | |\r\n 134217728 -> 268435455 : 0 | |\r\n 268435456 -> 536870911 : 0 | |\r\n 536870912 -> 1073741823 : 0 | |\r\n 1073741824 -> 2147483647 : 0 | |\r\n 2147483648 -> 4294967295 : 0 | |\r\n 4294967296 -> 8589934591 : 0 | |\r\n 8589934592 -> 17179869183 : 0 | |\r\n 17179869184 -> 34359738367 : 0 | |\r\n 34359738368 -> 68719476735 : 0 | |\r\n 68719476736 -> 137438953471 : 0 | |\r\n 137438953472 -> 274877906943 : 0 | |\r\n 274877906944 -> 549755813887 : 0 | |\r\n 549755813888 -> 1099511627775 : 0 | |\r\n 1099511627776 -> 2199023255551 : 0 | |\r\n 2199023255552 -> 4398046511103 : 0 | |\r\n 4398046511104 -> 8796093022207 : 0 | |\r\n 8796093022208 -> 17592186044415 : 0 | |\r\n 17592186044416 -> 35184372088831 : 0 | |\r\n 35184372088832 -> 70368744177663 : 0 | |\r\n 70368744177664 -> 140737488355327 : 0 | |\r\n 140737488355328 -> 281474976710655 : 0 | |\r\n 281474976710656 -> 562949953421311 : 0 | |\r\n 562949953421312 -> 1125899906842623 : 0 | |\r\n 1125899906842624 -> 2251799813685247 : 0 | |\r\n 2251799813685248 -> 4503599627370495 : 0 | |\r\n 4503599627370496 -> 9007199254740991 : 0 | |\r\n 9007199254740992 -> 18014398509481983 : 0 | |\r\n 18014398509481984 -> 36028797018963967 : 17 | |\r\n```\r\n\r\nAnd this one is after the bug is fixed:\r\n\r\n```\r\nTracing block device I/O... Hit Ctrl-C to end.\r\n^C\r\n usecs : count distribution\r\n 0 -> 1 : 0 | |\r\n 2 -> 3 : 0 | |\r\n 4 -> 7 : 0 | |\r\n 8 -> 15 : 0 | |\r\n 16 -> 31 : 163 | |\r\n 32 -> 63 : 339 | |\r\n 64 -> 127 : 258 | |\r\n 128 -> 255 : 2259 |** |\r\n 256 -> 511 : 5677 |****** |\r\n 512 -> 1023 : 32662 |****************************************|\r\n 1024 -> 2047 : 20252 |************************ |\r\n 2048 -> 4095 : 12544 |*************** |\r\n 4096 -> 8191 : 11006 |************* |\r\n 8192 -> 16383 : 1230 |* |\r\n 16384 -> 32767 : 201 | |\r\n 32768 -> 65535 : 544 | |\r\n 65536 -> 131071 : 746 | |\r\n 131072 -> 262143 : 881 |* |\r\n 262144 -> 524287 : 309 | |\r\n```\r\n\r\nThanks!ghprbCommentBody[buildbot, ok to test]ghprbGhRepositoryiovisor/bccghprbCredentialsId6d3daf13-69b8-48b1-9c8f-ec5353264113false<a title="Fix time going backwards on biolatency and biotop" href="https://github.com/iovisor/bcc/pull/2660">PR #2660</a>: Fix time going backwards on...#19010809777460664bcc-pr #190190false1901549SUCCESS1576998966671https://buildbot.iovisor.org/jenkins/user/davemarchevsky/my-views/view/all/job/bcc-pr/190/git190https://buildbot.iovisor.org/jenkins/user/davemarchevsky/my-views/view/all/job/bcc-pr/label=fc25/190/190https://buildbot.iovisor.org/jenkins/user/davemarchevsky/my-views/view/all/job/bcc-pr/label=fc26/190/190https://buildbot.iovisor.org/jenkins/user/davemarchevsky/my-views/view/all/job/bcc-pr/label=fc27/190/190https://buildbot.iovisor.org/jenkins/user/davemarchevsky/my-views/view/all/job/bcc-pr/label=fc28/190/190https://buildbot.iovisor.org/jenkins/user/davemarchevsky/my-views/view/all/job/bcc-pr/label=ubuntu1604/190/190https://buildbot.iovisor.org/jenkins/user/davemarchevsky/my-views/view/all/job/bcc-pr/label=ubuntu1710/190/190https://buildbot.iovisor.org/jenkins/user/davemarchevsky/my-views/view/all/job/bcc-pr/label=ubuntu1804/190/