On 19.02.2022 13:23, Konstantin Belousov wrote:
On Sat, Feb 19, 2022 at 12:14:16PM -0500, Alexander Motin wrote:
On 19.02.2022 12:02, Mike Karels wrote:
On 18 Feb 2022, at 20:55, Tomoaki AOKI wrote:
Just a thought, but can it be the reason with timing (e.g., rendezvous
within (i)threads, hardware controlls without using hardware timer)
problem?
On FreeBSD, IIUC, multi processor (multi core) implementation assumes
SMP (differs only clock speed) and end up with difference of
performance at same clock speed within P-core and E-core, possibly.
Another possibility is that the system is confused by having hyperthreading
on the P cores but not the E cores.
No, I've tried to disable SMT and different number of cores to make it look
identical and uniform for the scheduler. The only thing I could not test is
disabling all P cores to test only E, the motherboard does not allow that,
requiring at least one P core enabled.
Does the kernel select MWAIT as the idle method? If you set idle to spin,
is anything change?
By default kernel selects ACPI, using MWAIT:
machdep.idle: acpi
dev.cpu.0.cx_method: C1/mwait/hwc C2/mwait/hwc C3/mwait/hwc
I've tried to do in loader:
set machdep.idle_mwait=0
set machdep.idle="spin" (also tried "hlt")
, but without visible positive effects.
--
Alexander Motin
