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Miller" , "Eric Dumazet" , "Paolo Abeni" , , X-Mailer: aerc 0.21.0-threadmapfix References: <20261001-linux-mpnic-v1-0-6422ee74233a@gmail.com> <20261001-linux-mpnic-v1-4-6422ee74233a@gmail.com> In-Reply-To: On Fri Oct 2, 2026 at 8:53 PM EDT, Harshitha Ramamurthy wrote: > On Thu, Oct 1, 2026 at 9:41=E2=80=AFAM Daniel Zahka wrote: [...] > +void mpnic_napi_depletion_check(struct mpnic_net *mpn) >> +{ >> + int i, j, t; >> + >> + for (i =3D 0; i < mpn->num_napi; i++) { >> + struct mpnic_napi_vector *nv =3D mpn->napi[i]; >> + >> + for (t =3D nv->txt_count, j =3D 0; j < nv->rxt_count; j+= +, t++) { >> + /* Check if BDs posted covers a max sized frame >> + * + 1 BD held by RDE as a spare >> + * + 1 BD of extra safety margin >> + */ > > Curious how the "+ 1 BD of extra safety margin" was decided. I > understand the "+ 1 BD held by RDE as a spare" is because of HW > behaviour but wondering about the extra buffer descriptor - if it came > from testing or guarding against something specific. > The extra +1 isn't strictly necessary. The real lower bound is MPNIC_RX_HPQ_DROP_THRS + 1, which was derived from the design of the device and our napi poll implementation. I added an extra BD count because the actual bound doesn't matter as long as its conservative. Perhaps that's a bit superstitious. >> + if (mpnic_desc_used(&nv->qt[t].sub0) < >> + MPNIC_RX_HPQ_DROP_THRS + 2 || >> + mpnic_desc_used(&nv->qt[t].sub1) < >> + MPNIC_RX_PPQ_DROP_THRS + 2) { >> + mpnic_nv_irq_trigger(nv); >> + break; >> + } >> + } >> + } >> + >> + mpnic_wrfl(mpn->mpd); >> +} >> diff --git a/drivers/net/ethernet/meta/mpnic/mpnic_txrx.h b/drivers/net/= ethernet/meta/mpnic/mpnic_txrx.h >> index 9397010557eb..767d87a36c35 100644 >> --- a/drivers/net/ethernet/meta/mpnic/mpnic_txrx.h >> +++ b/drivers/net/ethernet/meta/mpnic/mpnic_txrx.h >> @@ -148,6 +148,7 @@ int mpnic_set_netif_queues(struct mpnic_net *mpn); >> void mpnic_reset_netif_queues(struct mpnic_net *mpn); >> void mpnic_napi_enable(struct mpnic_net *mpn); >> void mpnic_napi_disable(struct mpnic_net *mpn); >> +void mpnic_napi_depletion_check(struct mpnic_net *mpn); >> void mpnic_enable(struct mpnic_net *mpn); >> void mpnic_disable(struct mpnic_net *mpn); >> void mpnic_wait_all_queues_idle(struct mpnic_dev *mpd); >> >> -- >> 2.52.0 >> >>