On Sat, Feb 19, 2022 at 07:26:24PM -0500, Alexander Motin wrote:
> 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.
I was only interested in spin, for hlt there is no chance if spin did not
worked.
Ok, the next step is to get the CPU feature reports from P- vs. E- cores.
Patch below should work, with verbose boot.
diff --git a/sys/x86/x86/identcpu.c b/sys/x86/x86/identcpu.c
index 849f532dbf8b..9e4da4722f77 100644
--- a/sys/x86/x86/identcpu.c
+++ b/sys/x86/x86/identcpu.c
@@ -246,7 +246,7 @@ printcpuinfo(void)
u_int regs[4], i;
char *brand;
- printf("CPU: ");
+ printf("CPU %d: ", PCPU_GET(cpuid));
#ifdef __i386__
cpu_class = cpus[cpu].cpu_class;
strncpy(cpu_model, cpus[cpu].cpu_name, sizeof (cpu_model));
diff --git a/sys/x86/x86/mp_x86.c b/sys/x86/x86/mp_x86.c
index 3b0e25172d0d..4299eb5348e6 100644
--- a/sys/x86/x86/mp_x86.c
+++ b/sys/x86/x86/mp_x86.c
@@ -1089,7 +1089,7 @@ init_secondary_tail(void)
load_es(_udatasel);
load_fs(_ufssel);
#endif
-
+printcpuinfo();
mtx_unlock_spin(&ap_boot_mtx);
/* Wait until all the AP's are up. */
