----- Mail original -----
> De: "Paolo Bonzini" <pbonz...@redhat.com>
> À: "Sebastian Tanase" <sebastian.tan...@openwide.fr>, qemu-devel@nongnu.org
> Cc: aligu...@amazon.com, afaer...@suse.de, r...@twiddle.net, "peter maydell"
> <peter.mayd...@linaro.org>,
> mich...@walle.cc, a...@alex.org.uk, stefa...@redhat.com,
> lcapitul...@redhat.com, crobi...@redhat.com,
> arm...@redhat.com, wenchaoq...@gmail.com, quint...@redhat.com,
> kw...@redhat.com, m...@tls.msk.ru, m...@redhat.com
> Envoyé: Lundi 30 Juin 2014 19:11:41
> Objet: Re: [RFC PATCH V3 5/6] cpu_exec: Print to console if the guest is late
>
> Il 30/06/2014 15:59, Sebastian Tanase ha scritto:
> > If the align option is enabled, we print to the user whenever
> > the guest clock is behind the host clock in order for he/she
> > to have a hint about the actual performance. The maximum
> > print interval is 2s and we limit the number of messages to 100.
> > If desired, this can be changed in cpu-exec.c
> >
> > Signed-off-by: Sebastian Tanase <sebastian.tan...@openwide.fr>
> > Tested-by: Camille Bégué <camille.be...@openwide.fr>
> > ---
> > cpu-exec.c | 94
> > +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
> > 1 file changed, 90 insertions(+), 4 deletions(-)
> >
> > diff --git a/cpu-exec.c b/cpu-exec.c
> > index ac741b7..4a4533d 100644
> > --- a/cpu-exec.c
> > +++ b/cpu-exec.c
> > @@ -24,12 +24,21 @@
> > #include "sysemu/qtest.h"
> > #include "qemu/timer.h"
> >
> > -/* Structs and function pointers for delaying the host */
> > +/* Structs and function pointers for delaying the host
> > + and printing the clock difference between the guest
> > + and the host. */
> > typedef struct SyncClocks SyncClocks;
> > +typedef struct InformDelay InformDelay;
> > typedef void (*init_delay_func)(SyncClocks *sc,
> > + int64_t realtime_clock_value,
> > const CPUState *cpu);
> > typedef void (*perform_align_func)(SyncClocks *sc,
> > const CPUState *cpu);
> > +typedef void (*init_inform_delay_func)(InformDelay *indl,
> > + int64_t
> > realtime_clock_value);
> > +typedef void (*perform_print_func)(InformDelay *indl,
> > + int64_t diff_clk);
> > +
> > struct SyncClocks {
> > int64_t diff_clk;
> > int64_t original_instr_counter;
> > @@ -37,12 +46,22 @@ struct SyncClocks {
> > perform_align_func perform_align;
> > };
> >
> > +struct InformDelay {
> > + int64_t realtime_clock;
> > + unsigned int nb_prints;
> > + init_inform_delay_func init_inform_delay;
> > + perform_print_func perform_print;
> > +};
>
> I think these structs can be unified.
>
> > #if !defined(CONFIG_USER_ONLY)
> > /* Allow the guest to have a max 3ms advance.
> > * The difference between the 2 clocks could therefore
> > * oscillate around 0.
> > */
> > #define VM_CLOCK_ADVANCE 3000000
> > +#define THRESHOLD_REDUCE 1.5
> > +#define MAX_DELAY_PRINT_RATE 2
> > +#define MAX_NB_PRINTS 100
> >
> > static int64_t delay_host(int64_t diff_clk)
> > {
> > @@ -82,10 +101,11 @@ static void align_clocks(SyncClocks *sc, const
> > CPUState *cpu)
> > }
> >
> > static void init_delay_params(SyncClocks *sc,
> > + int64_t realtime_clock_value,
> > const CPUState *cpu)
> > {
> > static int64_t clocks_offset = -1;
> > - int64_t realtime_clock_value, virtual_clock_value;
> > + int64_t virtual_clock_value;
> > if (!icount_align_option) {
> > return;
> > }
> > @@ -97,7 +117,6 @@ static void init_delay_params(SyncClocks *sc,
> > Therefore we impose that the first time we run the cpu
> > the host and virtual clocks should be aligned; we don't
> > alter any of
> > the clocks, we just calculate the difference between them.
> > */
> > - realtime_clock_value = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
> > virtual_clock_value = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
> > if (clocks_offset == -1) {
> > clocks_offset = realtime_clock_value -
> > virtual_clock_value;
> > @@ -105,6 +124,47 @@ static void init_delay_params(SyncClocks *sc,
> > sc->diff_clk = virtual_clock_value - realtime_clock_value +
> > clocks_offset;
> > sc->original_instr_counter = cpu->icount_extra +
> > cpu->icount_decr.u16.low;
> > }
> > +static void print_delay(InformDelay *indl, int64_t diff_clk)
> > +{
> > + static float threshold_delay;
> > + static int64_t last_realtime_clock;
> > + if (icount_align_option &&
> > + (indl->realtime_clock - last_realtime_clock) /
> > 1000000000LL
> > + >= MAX_DELAY_PRINT_RATE && indl->nb_prints <
> > MAX_NB_PRINTS) {
> > + if (-diff_clk / (float)1000000000LL > threshold_delay) {
> > + threshold_delay = (-diff_clk / 1000000000LL) + 1;
> > + printf("Warning: The guest is late by %.1f to %.1f
> > seconds\n",
> > + threshold_delay - 1,
> > + threshold_delay);
> > + indl->nb_prints++;
> > + } else if (-diff_clk / (float)1000000000LL <
> > + (threshold_delay - THRESHOLD_REDUCE)) {
> > + threshold_delay = (-diff_clk / 1000000000LL) + 1;
> > + printf("Warning: The guest has reduced the delay and
> > is now "
> > + "late by %.1f to %.1f seconds\n",
> > + threshold_delay - 1,
> > + threshold_delay);
> > + indl->nb_prints++;
> > + }
> > + last_realtime_clock = indl->realtime_clock;
> > + }
> > +}
> > +
> > +static void init_inform(InformDelay *indl, int64_t
> > realtime_clock_value)
> > +{
> > + if (!icount_align_option) {
> > + return;
> > + }
> > + indl->realtime_clock = realtime_clock_value;
> > +}
> > +
> > +static void compute_value_of_rtc(int64_t *realtime_clock_value)
> > +{
> > + if (!icount_align_option) {
> > + return;
> > + }
> > + *realtime_clock_value =
> > qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
> > +}
> > #else
> > /* We don't use the align feature for User emulation
> > thus we add empty functions which shall be ignored
> > @@ -114,9 +174,21 @@ static void align_clocks(SyncClocks *sc, const
> > CPUState *cpu)
> > }
> >
> > static void init_delay_params(SyncClocks *sc,
> > + int64_t realtime_clock_value,
> > const CPUState *cpu)
> > {
> > }
> > +static void print_delay(InformDelay *indl, int64_t diff_clk)
> > +{
> > +}
> > +
> > +static void init_inform(InformDelay *indl, int64_t
> > realtime_clock_value)
> > +{
> > +}
> > +
> > +static void compute_value_of_rtc(int64_t *realtime_clock_value)
> > +{
> > +}
> > #endif /* CONFIG USER ONLY */
> >
> > void cpu_loop_exit(CPUState *cpu)
> > @@ -324,10 +396,16 @@ int cpu_exec(CPUArchState *env)
> > uint8_t *tc_ptr;
> > uintptr_t next_tb;
> > /* Delay algorithm */
> > + int64_t realtime_clock_value;
> > static SyncClocks sc = {
> > .init_delay = init_delay_params,
> > .perform_align = align_clocks
> > };
> > + /* Print delay control */
> > + static InformDelay inform_delay = {
> > + .init_inform_delay = init_inform,
> > + .perform_print = print_delay
> > + };
> > /* This must be volatile so it is not trashed by longjmp() */
> > volatile bool have_tb_lock = false;
> >
> > @@ -384,11 +462,19 @@ int cpu_exec(CPUArchState *env)
> > #endif
> > cpu->exception_index = -1;
> >
> > + /* Calculating the realtime is expensive so we do it once here
> > + and then pass this value around. */
> > + compute_value_of_rtc(&realtime_clock_value);
>
> Can this (and compute_clocks_offset) all remain part of
> init_delay_params?
>
> > /* Calculate difference between guest clock and host clock.
> > This delay includes the delay of the last cycle, so
> > what we have to do is sleep until it is 0. As for the
> > advance/delay we gain here, we try to fix it next time. */
> > - sc.init_delay(&sc, cpu);
> > + inform_delay.init_inform_delay(&inform_delay,
> > realtime_clock_value);
> > + sc.init_delay(&sc, realtime_clock_value, cpu);
> > + /* Print every 2s max if the guest is late. We limit the
> > number
> > + of printed messages to NB_PRINT_MAX(currently 100) */
> > + inform_delay.perform_print(&inform_delay, sc.diff_clk);
>
> This, too.
>
> Paolo
>
Unifying the 2 structs will certainly make this possible.
Sebastian
> > +
> > /* prepare setjmp context for exception handling */
> > for(;;) {
> > if (sigsetjmp(cpu->jmp_env, 0) == 0) {
> >
>
>
>
