{"action":"created","issue":{"url":"https://api.github.com/repos/raspberrypi/linux/issues/1216","labels_url":"https://api.github.com/repos/raspberrypi/linux/issues/1216/labels{/name}","comments_url":"https://api.github.com/repos/raspberrypi/linux/issues/1216/comments","events_url":"https://api.github.com/repos/raspberrypi/linux/issues/1216/events","html_url":"https://github.com/raspberrypi/linux/issues/1216","id":120644562,"number":1216,"title":"Change to 250hz and voluntary preemption","user":{"login":"robingroppe","id":11094654,"avatar_url":"https://avatars.githubusercontent.com/u/11094654?v=3","gravatar_id":"","url":"https://api.github.com/users/robingroppe","html_url":"https://github.com/robingroppe","followers_url":"https://api.github.com/users/robingroppe/followers","following_url":"https://api.github.com/users/robingroppe/following{/other_user}","gists_url":"https://api.github.com/users/robingroppe/gists{/gist_id}","starred_url":"https://api.github.com/users/robingroppe/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/robingroppe/subscriptions","organizations_url":"https://api.github.com/users/robingroppe/orgs","repos_url":"https://api.github.com/users/robingroppe/repos","events_url":"https://api.github.com/users/robingroppe/events{/privacy}","received_events_url":"https://api.github.com/users/robingroppe/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":8,"created_at":"2015-12-06T16:40:37Z","updated_at":"2015-12-07T13:37:43Z","closed_at":null,"body":"Please change the kernel to 250hz and voluntary preemption.\r\n\r\nIn everyday use my Pi with the modified kernel can take more work while still being responsive to all other running tasks. For example when i run the MumbleRubyPluginbot, with the stock kernel, which needs to be fed with data every 20ms or so and start an apt upgrade of some packets it quickly starts to lag.\r\nWith the modified kernel everything is fine.\r\nYou said you would need some evidence. I ran UnixBench on both kernels.\r\nI cant tell much about starting graphical apps, because my pi is running headless but i guess you guys are having crosscompilers set up and can easily build a modified kernel.\r\nBy the way these two things i am mentioning are also used in almost every stockkernel in most distributions (Debian, Ubuntu...). And in my opinion there is a reason for that.\r\n\r\nUnixbench Stock Kernel: https://robingroppe.de/media/rpi2/orig.txt\r\nUnixbench Modified Kernel: https://robingroppe.de/media/rpi2/mod.txt"},"comment":{"url":"https://api.github.com/repos/raspberrypi/linux/issues/comments/162526576","html_url":"https://github.com/raspberrypi/linux/issues/1216#issuecomment-162526576","issue_url":"https://api.github.com/repos/raspberrypi/linux/issues/1216","id":162526576,"user":{"login":"robingroppe","id":11094654,"avatar_url":"https://avatars.githubusercontent.com/u/11094654?v=3","gravatar_id":"","url":"https://api.github.com/users/robingroppe","html_url":"https://github.com/robingroppe","followers_url":"https://api.github.com/users/robingroppe/followers","following_url":"https://api.github.com/users/robingroppe/following{/other_user}","gists_url":"https://api.github.com/users/robingroppe/gists{/gist_id}","starred_url":"https://api.github.com/users/robingroppe/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/robingroppe/subscriptions","organizations_url":"https://api.github.com/users/robingroppe/orgs","repos_url":"https://api.github.com/users/robingroppe/repos","events_url":"https://api.github.com/users/robingroppe/events{/privacy}","received_events_url":"https://api.github.com/users/robingroppe/received_events","type":"User","site_admin":false},"created_at":"2015-12-07T13:37:43Z","updated_at":"2015-12-07T13:37:43Z","body":"Okay. Voluntary causes the throughput to drop slightly but full preemption\nlike you are using right now causes even more drop of throughput and\nadditionally kernel overhead.\nAm 07.12.2015 14:35 schrieb \"popcornmix\" <notifications@github.com>:\n\n> No it may help latency but it won't improve throughput.\n>\n> These new preemption points have been selected to reduce the maximum\n> latency of rescheduling, providing faster application reactions, at the\n> cost of slightly lower throughput.\n>\n> http://cateee.net/lkddb/web-lkddb/PREEMPT_VOLUNTARY.html\n>\n> —\n> Reply to this email directly or view it on GitHub\n> <https://github.com/raspberrypi/linux/issues/1216#issuecomment-162526062>.\n>\n"}}