Date: Sat, 25 Jul 2026 21:29:44 +0000 From: Kevin Bowling <kbowling@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 941113a0097e - main - e1000: fix 82574 MSI-X interrupt throttling Message-ID: <6a652ac8.43823.679927a9@gitrepo.freebsd.org>
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The branch main has been updated by kbowling: URL: https://cgit.FreeBSD.org/src/commit/?id=941113a0097ea047bd493f7f78b384718249779d commit 941113a0097ea047bd493f7f78b384718249779d Author: Kevin Bowling <kbowling@FreeBSD.org> AuthorDate: 2026-07-25 10:43:28 +0000 Commit: Kevin Bowling <kbowling@FreeBSD.org> CommitDate: 2026-07-25 21:27:51 +0000 e1000: fix 82574 MSI-X interrupt throttling em_newitr() and the per-queue interrupt_rate sysctl both tested que->msix to decide whether an 82574 is running in MSI-X mode. 0 is a valid MSI-X vector so queue 0 was misclassified as legacy/MSI. Test sc->intr_type == IFLIB_INTR_MSIX instead. While here, index the tx EITR read by tque->msix rather than tque->me so it matches the register em_newitr() actually writes; the two differ once tx_num_queues exceeds rx_num_queues. Also seed que->itr_setting in em_initialize_receive_unit() with the rate the hardware was just programmed with. Otherwise an itr_setting left over from AIM across an interface re-init makes the change detection in em_newitr() suppress the write that would restore it, leaving the hardware at the default rate while software believes otherwise. Fixes: 3e501ef89667 ("e1000: Re-add AIM") MFC after: 3 days --- sys/dev/e1000/if_em.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/sys/dev/e1000/if_em.c b/sys/dev/e1000/if_em.c index 5547c4ec8614..1e54d5ea998d 100644 --- a/sys/dev/e1000/if_em.c +++ b/sys/dev/e1000/if_em.c @@ -1792,7 +1792,8 @@ em_set_next_itr: if (newitr != que->itr_setting) { que->itr_setting = newitr; - if (hw->mac.type == e1000_82574 && que->msix) { + if (hw->mac.type == e1000_82574 && + sc->intr_type == IFLIB_INTR_MSIX) { E1000_WRITE_REG(hw, E1000_EITR_82574(que->msix), que->itr_setting); @@ -3834,6 +3835,19 @@ em_initialize_receive_unit(if_ctx_t ctx) /* Set the default interrupt throttling rate */ E1000_WRITE_REG(hw, E1000_ITR, EM_INTS_TO_ITR(em_max_interrupt_rate)); + + /* + * The 82574 MSI-X EITR registers are programmed + * with the same value further below. Either way + * the hardware now holds the default rate, so seed + * the software copy to match; otherwise a stale + * itr_setting left over from AIM makes em_newitr() + * skip the write that would restore it. + */ + for (i = 0, que = sc->rx_queues; i < sc->rx_num_queues; + i++, que++) + que->itr_setting = + EM_INTS_TO_ITR(em_max_interrupt_rate); } /* XXX TEMPORARY WORKAROUND: on some systems with 82573 @@ -4957,8 +4971,9 @@ em_sysctl_interrupt_rate_handler(SYSCTL_HANDLER_ARGS) hw = &tque->sc->hw; if (hw->mac.type >= igb_mac_min) reg = E1000_READ_REG(hw, E1000_EITR(tque->me)); - else if (hw->mac.type == e1000_82574 && tque->msix) - reg = E1000_READ_REG(hw, E1000_EITR_82574(tque->me)); + else if (hw->mac.type == e1000_82574 && + tque->sc->intr_type == IFLIB_INTR_MSIX) + reg = E1000_READ_REG(hw, E1000_EITR_82574(tque->msix)); else reg = E1000_READ_REG(hw, E1000_ITR); } else { @@ -4966,7 +4981,8 @@ em_sysctl_interrupt_rate_handler(SYSCTL_HANDLER_ARGS) hw = &rque->sc->hw; if (hw->mac.type >= igb_mac_min) reg = E1000_READ_REG(hw, E1000_EITR(rque->msix)); - else if (hw->mac.type == e1000_82574 && rque->msix) + else if (hw->mac.type == e1000_82574 && + rque->sc->intr_type == IFLIB_INTR_MSIX) reg = E1000_READ_REG(hw, E1000_EITR_82574(rque->msix)); elsehome | help
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