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Fix automatic eventtimer hardware selection when ARAT

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(APIC-Timer-always-running) is not implemented.

If machine has ncpus >= 8 and non-FSB interrupt routing from HPET,
default HPET eventtimer quality 450 is reduced by 100, i.e. it is
350. On the other hand, LAPIC default quality is 600 and it is reduced
by 200 if ARAT is not reported. We end up with HPET quality 350 <
LAPIC quality 400, despite ARAT is not set.  Then, since deep Cx
states are active by default, eventtimer fail.

E.g., on Nehalem Core i7 CPU and X58 chipset, LAPIC only works in
C0/C1/C1E and HPET does not implement FSB mode, which otherwise
requires manual switch to HPET to get working system.

Set LAPIC eventtimer quality to 100 if no ARAT.
While there, do not ignore deadlint TSC mode for LAPIC timer if ARAT
is not implemented.  If user manually selected LAPIC eventtimer on
such CPU, there is no reason to not use deadline if available and not
disabled administratively.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2016-11-26 10:33:53 +00:00
parent 6873df70b2
commit 83a288f434
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=309189
1 changed files with 3 additions and 2 deletions
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5
sys/x86/x86/local_apic.c
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@ -478,8 +478,9 @@ native_lapic_init(vm_paddr_t addr)
lapic_et.et_quality = 600;
if (!arat) {
lapic_et.et_flags |= ET_FLAGS_C3STOP;
lapic_et.et_quality -= 200;
} else if ((cpu_feature & CPUID_TSC) != 0 &&
lapic_et.et_quality = 100;
}
if ((cpu_feature & CPUID_TSC) != 0 &&
(cpu_feature2 & CPUID2_TSCDLT) != 0 &&
tsc_is_invariant && tsc_freq != 0) {
lapic_timer_tsc_deadline = 1;