----- 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,
> "camille begue" <camille.be...@openwide.fr>, "pierre lemagourou"
> <pierre.lemagou...@openwide.fr>, "jeremy rosen"
> <jeremy.ro...@openwide.fr>
> Envoyé: Vendredi 13 Juin 2014 12:29:36
> Objet: Re: [RFC PATCH V2 5/5] cpu_exec: Print to console if the guest is late
>
> Il 13/06/2014 11:40, 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 so as not to spam the console.
> >
> > Signed-off-by: Sebastian Tanase <sebastian.tan...@openwide.fr>
> > Tested-by: Camille Bégué <camille.be...@openwide.fr>
> > ---
> > cpu-exec.c | 32 +++++++++++++++++++++++++++++++-
> > 1 file changed, 31 insertions(+), 1 deletion(-)
> >
> > diff --git a/cpu-exec.c b/cpu-exec.c
> > index 5a3bc5e..a386592 100644
> > --- a/cpu-exec.c
> > +++ b/cpu-exec.c
> > @@ -216,6 +216,8 @@ static void
> > cpu_handle_debug_exception(CPUArchState *env)
> > * oscillate around 0.
> > */
> > #define VM_CLOCK_ADVANCE 3000000
> > +#define THRESHOLD_REDUCE 1.5
> > +#define MAX_DELAY_PRINT_RATE 2
> >
> > static int64_t delay_host(int64_t diff_clk)
> > {
> > @@ -257,6 +259,29 @@ static int64_t align_clocks(int64_t diff_clk,
> > int64_t *oic, CPUState *cpu)
> > return diff_clk;
> > }
> >
> > +static void print_delay(int64_t diff_clk, int64_t realtime_clock)
> > +{
> > + static float threshold_delay;
> > + static int64_t last_realtime_clock;
> > +
> > + if ((realtime_clock - last_realtime_clock) / 1000000000LL
> > + >= MAX_DELAY_PRINT_RATE) {
> > + 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);
> > + } 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);
> > + }
> > + last_realtime_clock = realtime_clock;
> > + }
> > +}
>
> Perhaps stop printing the message after the first 50-100 times?
>
> Paolo
>
Thank you very much for your feedback.
Maybe adding a monitor command (info drift) would be better ? Then
the user would not be spammed by printfs.
Sebastian Tanase
> > #endif /* CONFIG USER ONLY */
> >
> > /* main execution loop */
> > @@ -278,6 +303,8 @@ int cpu_exec(CPUArchState *env)
> > uint8_t *tc_ptr;
> > uintptr_t next_tb;
> > #if !(defined(CONFIG_USER_ONLY))
> > + /* Print delay control */
> > + static int64_t realtime_clock;
> > /* Delay algorithm */
> > int64_t diff_clk, original_instr_counter;
> > #endif
> > @@ -342,9 +369,12 @@ int cpu_exec(CPUArchState *env)
> > 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.
> > */
> > + realtime_clock = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
> > diff_clk = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) -
> > - qemu_clock_get_ns(QEMU_CLOCK_REALTIME) +
> > clocks_offset;
> > + realtime_clock + clocks_offset;
> > original_instr_counter = cpu->icount_extra +
> > cpu->icount_decr.u16.low;
> > + /* Print (every 2s max) if the guest is behind the host */
> > + print_delay(diff_clk, realtime_clock);
> > }
> > #endif
> > /* prepare setjmp context for exception handling */
> >
>
>
