On 19/06/2019 14:10, Greg Troxel wrote:
THIS is the problem. The kernel has mis-identified your TSC frequency massively somehow. You have a 2.8GHz process which means the invariant TSC should be running at 2.8GHZ. There is a capability bit for invariant TSC and if your processor doesn't have that capability bit set NetBSD sets the TSC quality to a very low number (might even be negative).Patrick Welche <prlw1%cam.ac.uk@localhost> writes:On Tue, Jun 18, 2019 at 04:56:33PM -0000, Michael van Elst wrote:gdt%lexort.com@localhost (Greg Troxel) writes:-timecounter: Timecounter "ACPI-Safe" frequency 3579545 Hz quality 900 +timecounter: Timecounter "ACPI-Fast" frequency 3579545 Hz quality 1000-timecounter: Timecounter "TSC" frequency 2800071320 Hz quality 3000 +timecounter: Timecounter "TSC" frequency 3920113160 Hz quality 3000
which if accurate gives us a small window for bisecting.
Bad news is I've seen this come and go since NetBSD 6 on i386 :(
I've seen it come and go with the SAME kernel on laptop hardware which has a known to be invariant TSC. I think NetBSD might be assuming that the CPU is running at a particular speed to calculate the frequency so if your BIOS starts the CPU at a lower speed (e.g laptop on battery) you can get wild results.I will try the older kernel, and then see if I can search. I wonder if somehow with different code the cpu/tsc is being configured so that tsc doesn't do what it used to. Is anyone else seeing this problem?
I didn't use BSD on the machine where it happened very often so I went with the sysctl workround and never really chased it. Sorry. :(
Mike