| Message ID | 20210809131057.1694145-9-danielhb413@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | PMU-EBB support for PPC64 TCG | expand |
On 8/9/21 3:10 AM, Daniel Henrique Barboza wrote: > +/* > + * Set arbitrarily based on clock-frequency values used in PNV > + * and SPAPR code. > + */ > +#define PPC_CPU_FREQ 1000000000 > > static uint64_t get_cycles(uint64_t icount_delta) > { > - /* Placeholder value */ > - return icount_delta * 4; > + return muldiv64(icount_to_ns(icount_delta), PPC_CPU_FREQ, > + NANOSECONDS_PER_SECOND); So, unless you're going to do something real, you might as well just return icount_to_ns, and skip all of the no-op scaling. r~
diff --git a/target/ppc/pmu_book3s_helper.c b/target/ppc/pmu_book3s_helper.c index 6292b96db9..91bb82e699 100644 --- a/target/ppc/pmu_book3s_helper.c +++ b/target/ppc/pmu_book3s_helper.c @@ -17,11 +17,16 @@ #include "qemu/error-report.h" #include "qemu/main-loop.h" +/* + * Set arbitrarily based on clock-frequency values used in PNV + * and SPAPR code. + */ +#define PPC_CPU_FREQ 1000000000 static uint64_t get_cycles(uint64_t icount_delta) { - /* Placeholder value */ - return icount_delta * 4; + return muldiv64(icount_to_ns(icount_delta), PPC_CPU_FREQ, + NANOSECONDS_PER_SECOND); } static void update_PMC_PM_INST_CMPL(CPUPPCState *env, int sprn,
We've been considering that PM_CYC is always 4x the number of instructions sampled. This is not accurate due to several reasons, including icount shift. Replace it with a more accurate logic that returns the elapsed cycle count of the sampled period, based on what the ARM CPU already does in target/arm/helper.c, cycles_get_count(). Multiply the amount of ns passed in the icount period (which considers icount shift) with the CPU frequency. The PPC CPU clock frequency has different values depending on the CPU implementation. We're defaulting it to 1GHz since it's the same value used by PNV and pSeries CPUs. Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com> --- target/ppc/pmu_book3s_helper.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)