qemu/target
Greg Kurz 9cbcfb5924 target/ppc/kvm: Cache timebase frequency
Each vCPU core exposes its timebase frequency in the DT. When running
under KVM, this means parsing /proc/cpuinfo in order to get the timebase
frequency of the host CPU.

The parsing appears to slow down the boot quite a bit with higher number
of cores:

# of cores     seconds spent in spapr_dt_cpus()
      8                  0.550122
     16                  1.342375
     32                  2.850316
     64                  5.922505
     96                  9.109224
    128                 12.245504
    256                 24.957236
    384                 37.389113

The timebase frequency of the host CPU is identical for all
cores and it is an invariant for the VM lifetime. Cache it
instead of doing the same expensive parsing again and again.

Rename kvmppc_get_tbfreq() to kvmppc_get_tbfreq_procfs() and
rename the 'retval' variable to make it clear it is used as
fallback only. Come up with a new version of kvmppc_get_tbfreq()
that calls kvmppc_get_tbfreq_procfs() only once and keep the
value in a static.

Zero is certainly not a valid value for the timebase frequency.
Treat atoi() returning zero as another parsing error and return
the fallback value instead. This allows kvmppc_get_tbfreq() to
use zero as an indicator that kvmppc_get_tbfreq_procfs() hasn't
been called yet.

With this patch applied:

    384                 0.518382

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <161600382766.1780699.6787739229984093959.stgit@bahia.lan>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2021-03-31 11:10:50 +11:00
..
alpha cpu: tcg_ops: move to tcg-cpu-ops.h, keep a pointer in CPUClass 2021-02-05 10:24:15 -10:00
arm target/arm: Make number of counters in PMCR follow the CPU 2021-03-30 14:05:33 +01:00
avr target/avr: Fix interrupt execution 2021-03-15 00:39:52 +01:00
cris target/cris: Plug leakage of TCG temporaries 2021-02-22 09:04:58 +01:00
hexagon target/hexagon/gen_tcg_funcs: Fix a typo 2021-03-09 21:31:34 +01:00
hppa exec: Use cpu_untagged_addr in g2h; split out g2h_untagged 2021-02-16 11:04:53 +00:00
i386 i386: Make migration fail when Hyper-V reenlightenment was enabled but 'user_tsc_khz' is unset 2021-03-19 08:48:18 -04:00
lm32 semihosting: Move include/hw/semihosting/ -> include/semihosting/ 2021-03-10 15:34:12 +00:00
m68k Prepare MacOS ROM support: 2021-03-12 18:56:56 +00:00
microblaze cpu: tcg_ops: move to tcg-cpu-ops.h, keep a pointer in CPUClass 2021-02-05 10:24:15 -10:00
mips target/mips/mxu_translate.c: Fix array overrun for D16MIN/D16MAX 2021-03-22 15:05:41 +01:00
moxie exec: Move TranslationBlock typedef to qemu/typedefs.h 2021-02-18 08:19:08 +00:00
nios2 semihosting: Move include/hw/semihosting/ -> include/semihosting/ 2021-03-10 15:34:12 +00:00
openrisc cpu: tcg_ops: move to tcg-cpu-ops.h, keep a pointer in CPUClass 2021-02-05 10:24:15 -10:00
ppc target/ppc/kvm: Cache timebase frequency 2021-03-31 11:10:50 +11:00
riscv target/riscv: Prevent lost illegal instruction exceptions 2021-03-22 21:54:40 -04:00
rx cpu: tcg_ops: move to tcg-cpu-ops.h, keep a pointer in CPUClass 2021-02-05 10:24:15 -10:00
s390x s390x: move S390_ADAPTER_SUPPRESSIBLE 2021-03-26 09:33:50 +01:00
sh4 target/sh4: Remove unused definitions 2021-03-06 16:18:42 +01:00
sparc cpu: tcg_ops: move to tcg-cpu-ops.h, keep a pointer in CPUClass 2021-02-05 10:24:15 -10:00
tricore target/tricore: Fix OPC2_32_RRPW_EXTR for width=0 2021-03-14 14:49:01 +01:00
unicore32 semihosting: Move include/hw/semihosting/ -> include/semihosting/ 2021-03-10 15:34:12 +00:00
xtensa semihosting: Move include/hw/semihosting/ -> include/semihosting/ 2021-03-10 15:34:12 +00:00
meson.build Remove deprecated target tilegx 2021-03-09 11:26:32 +01:00