Re: [PATCH 4/9] net/igb: Fix interrupt throttling interval calculation

[Akihiko Odaki <akihiko.odaki@daynix.com>]

On 2025/01/18 2:03, Nicholas Piggin wrote:
> IGB throttling granularity is 1us, and interval field is in bits 2..14
> of the EITRx registers.
> 
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

Please add Fixes: as described in docs/devel/submitting-a-patch.rst

> ---
>   hw/net/igb_regs.h | 3 +++
>   hw/net/igb_core.c | 7 ++++---
>   2 files changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/net/igb_regs.h b/hw/net/igb_regs.h
> index 4dc4c31da27..1ed5ee5039a 100644
> --- a/hw/net/igb_regs.h
> +++ b/hw/net/igb_regs.h
> @@ -146,6 +146,9 @@ union e1000_adv_rx_desc {
>   #define IGB_82576_VF_DEV_ID        0x10CA
>   #define IGB_I350_VF_DEV_ID         0x1520
>   
> +/* Delay increments in nanoseconds for interrupt throttling registers */
> +#define IGB_INTR_THROTTLING_NS_RES (1000)
> +
>   /* VLAN info */
>   #define IGB_TX_FLAGS_VLAN_MASK     0xffff0000
>   #define IGB_TX_FLAGS_VLAN_SHIFT    16
> diff --git a/hw/net/igb_core.c b/hw/net/igb_core.c
> index 39e3ce1c8fe..94f9785749a 100644
> --- a/hw/net/igb_core.c
> +++ b/hw/net/igb_core.c
> @@ -142,8 +142,9 @@ static void igb_msix_notify(IGBCore *core, unsigned int cause)
>   static inline void
>   igb_intrmgr_rearm_timer(IGBIntrDelayTimer *timer)
>   {
> -    int64_t delay_ns = (int64_t) timer->core->mac[timer->delay_reg] *
> -                                 timer->delay_resolution_ns;
> +    int64_t delay_ns =
> +            (int64_t)((timer->core->mac[timer->delay_reg] & 0x7FFC) >> 2) *
> +                     timer->delay_resolution_ns;
>   
>       trace_e1000e_irq_rearm_timer(timer->delay_reg << 2, delay_ns);
>   
> @@ -180,7 +181,7 @@ igb_intrmgr_initialize_all_timers(IGBCore *core, bool create)
>       for (i = 0; i < IGB_INTR_NUM; i++) {
>           core->eitr[i].core = core;
>           core->eitr[i].delay_reg = EITR0 + i;
> -        core->eitr[i].delay_resolution_ns = E1000_INTR_DELAY_NS_RES;
> +        core->eitr[i].delay_resolution_ns = IGB_INTR_THROTTLING_NS_RES;
>       }
>   
>       if (!create) {