HPET vs other timers
nate at root.org
Sun Jun 3 00:30:41 UTC 2007
Poul-Henning Kamp wrote:
> Nate Lawson wrote:
>>> Anyone able to speculate why though? HPET only reads 32 bits from a
>>> memory mapped region. No locking or other requirements. ACPI_timer
>>> does multiple IO ops, which according to bde@ are much slower than
>>> memory reads.
> HPET needs to do metastability mitigation and is not "just a read
> from a memory mapped region".
If it does, then it's not implemented yet:
hpet_get_timecount(struct timecounter *tc)
struct acpi_hpet_softc *sc;
sc = tc->tc_priv;
return (bus_read_4(sc->mem_res, HPET_OFFSET_VALUE));
Are you sure you're not thinking of ACPI-safe?
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