Summary: | Enable option TCPHPTS in the kernel causes a large % of interruptions if there is no HPET eventtimer in the system | ||
---|---|---|---|
Product: | Base System | Reporter: | Vladyslav V. Prodan <admin> |
Component: | kern | Assignee: | Michael Tuexen <tuexen> |
Status: | Closed FIXED | ||
Severity: | Affects Some People | CC: | chris, emaste, markj, net, rgrimes, rozhuk.im, rrs, thj, tuexen |
Priority: | --- | Keywords: | performance |
Version: | 12.1-RELEASE | Flags: | koobs:
mfc-stable12+
|
Hardware: | amd64 | ||
OS: | Any |
Description
Vladyslav V. Prodan
2019-11-13 23:27:00 UTC
CC rrs Is this a problem on HEAD as well? I'm not sure if some of the recent TCP changes might have fixed this. rrs is working on it. On VBox even with hpet - same strange CPU load, especially with 4+ cores. I think I can reproduce this on 12-stable (r362275) With options TCPHPTS, I see a consistent interrupt load on a bhyve vm on a 12.1 host. CPU: 0.0% user, 0.0% nice, 0.0% system, 8.0% interrupt, 91.9% idle Without TCPHPTS the vm is almost completely idle and there is no interrupt load. Meant to add: root@freebsd-stable:~ # sysctl kern.eventtimer kern.eventtimer.periodic: 0 kern.eventtimer.timer: LAPIC kern.eventtimer.idletick: 0 kern.eventtimer.singlemul: 4 kern.eventtimer.choice: LAPIC(600) HPET(550) i8254(100) RTC(0) kern.eventtimer.et.HPET.quality: 550 kern.eventtimer.et.HPET.frequency: 16777216 kern.eventtimer.et.HPET.flags: 7 kern.eventtimer.et.i8254.quality: 100 kern.eventtimer.et.i8254.frequency: 1193182 kern.eventtimer.et.i8254.flags: 1 kern.eventtimer.et.RTC.quality: 0 kern.eventtimer.et.RTC.frequency: 32768 kern.eventtimer.et.RTC.flags: 17 kern.eventtimer.et.LAPIC.quality: 600 kern.eventtimer.et.LAPIC.frequency: 67695695 kern.eventtimer.et.LAPIC.flags: 7 I could reproduce the problem using the settings of tjh@. More precisely, r362879, in a bhyve VM using a GENERIC kernel with TCPHPTS added, I observe a 5% to 6% interrupt load. Using r362880 this does not happen anymore. Also I don't observe an interrupt load on VBox with an up-to-date stable/12 machine. I think the issue is already solved by https://svnweb.freebsd.org/changeset/base/362880 and therefore I'm closing this issue. If the problem can still be reproduced on a system with r362880 or higher, please reopen. |