On Mon, Jul 24, 2023 at 04:54:22PM +0800, Evanzhang wrote:
> under heavy workloads,irq_coalesced could up to 30+,
> after modification EXTERNAL_INTERRUPT reduce by 40%
>
> before:
> Analyze events for all VMs, all VCPUs:
> VM-EXIT Samples Samples% Time%
>
> EPT_VIOLATION 9833984 63.41% 15.96%
> IO_INSTRUCTION 2160843 13.93% 50.07%
> EXTERNAL_INTERRUPT 1949267 12.57% 0.89%
> APIC_WRITE 767795 4.95% 0.55%
> EOI_INDUCED 615308 3.97% 0.30%
> HLT 130821 0.84% 31.77%
>
> after:
> Analyze events for all VMs, all VCPUs:
> VM-EXIT Samples Samples% Time%
>
> EPT_VIOLATION 5238031 50.91% 6.44%
> IO_INSTRUCTION 2257658 21.94% 54.88%
> EXTERNAL_INTERRUPT 1160086 11.28% 0.61%
> APIC_WRITE 780454 7.59% 0.54%
> EOI_INDUCED 615309 5.98% 0.28%
> HLT 179703 1.75% 36.87%
>
> Signed-off-by: Evanzhang <evanzh...@archeros.com>
Paolo do you mind picking this old patch up?
Reviewed-by: Michael S. Tsirkin <m...@redhat.com>
> ---
> hw/rtc/mc146818rtc.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/hw/rtc/mc146818rtc.c b/hw/rtc/mc146818rtc.c
> index c27c362..2995078 100644
> --- a/hw/rtc/mc146818rtc.c
> +++ b/hw/rtc/mc146818rtc.c
> @@ -96,8 +96,8 @@ static void rtc_coalesced_timer_update(MC146818RtcState *s)
> if (s->irq_coalesced == 0) {
> timer_del(s->coalesced_timer);
> } else {
> - /* divide each RTC interval to 2 - 8 smaller intervals */
> - int c = MIN(s->irq_coalesced, 7) + 1;
> + /* divide each RTC interval to 2 - 32 smaller intervals */
> + int c = MIN(s->irq_coalesced, 31) + 1;
> int64_t next_clock = qemu_clock_get_ns(rtc_clock) +
> periodic_clock_to_ns(s->period / c);
> timer_mod(s->coalesced_timer, next_clock);
> --
> 2.9.5
