Date: Sun, 26 Jul 2026 01:01:10 +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: dc4a5087b160 - main - e1000: restore packet-size AIM Message-ID: <6a655c56.32e36.3041c7cc@gitrepo.freebsd.org>
index | next in thread | raw e-mail
The branch main has been updated by kbowling: URL: https://cgit.FreeBSD.org/src/commit/?id=dc4a5087b160c1a94d135ab636642defe2c71c20 commit dc4a5087b160c1a94d135ab636642defe2c71c20 Author: Kevin Bowling <kbowling@FreeBSD.org> AuthorDate: 2026-07-25 23:49:31 +0000 Commit: Kevin Bowling <kbowling@FreeBSD.org> CommitDate: 2026-07-26 01:00:02 +0000 e1000: restore packet-size AIM Restore the packet-size calculation introduced in a69ed8dfb381 and used by igb(4) until the iflib conversion in f2d6ace4a684. It derives interrupt holdoff from average packet size, so RSS queue count does not change its behavior. The calculation follows the pre-iflib code. Retain the current normal and low-latency rate caps, and keep the current setting when an interval has no usable sample. Fixes: 3e501ef89667 ("e1000: Re-add AIM") MFC after: 1 week --- sys/dev/e1000/if_em.c | 170 +++++++++++++++++++------------------------------- sys/dev/e1000/if_em.h | 11 +++- 2 files changed, 73 insertions(+), 108 deletions(-) diff --git a/sys/dev/e1000/if_em.c b/sys/dev/e1000/if_em.c index 40a5e9f75de9..e447008eafff 100644 --- a/sys/dev/e1000/if_em.c +++ b/sys/dev/e1000/if_em.c @@ -1692,12 +1692,60 @@ em_aim_tx_delta(struct tx_ring *txr, u32 *bytes, u32 *packets) txr->tx_packets_last = now_packets; } -enum itr_latency_target { - itr_latency_disabled = 0, - itr_latency_lowest = 1, - itr_latency_low = 2, - itr_latency_bulk = 3 -}; +/********************************************************************* + * + * Do Adaptive Interrupt Moderation: + * - Calculate based on average size over the last interval + * + * Returns interrupts per second rather than a register value, so that the + * caller's EM_INTS_TO_ITR()/IGB_INTS_TO_EITR() conversion applies, or zero + * if the interval carried no packet to measure. + * + *********************************************************************/ +static u32 +em_ring_itr(struct e1000_softc *sc, u32 rxbytes, u32 rxpackets, u32 txbytes, + u32 txpackets) +{ + u32 newitr = 0; + + if (txbytes && txpackets) + newitr = txbytes / txpackets; + if (rxbytes && rxpackets) + newitr = max(newitr, rxbytes / rxpackets); + + /* + * No packet was observed, so there is no size to work from. Report no + * observation and let the caller keep the rate it already has. + */ + if (newitr == 0) + return (0); + + newitr += 24; /* account for hardware frame, crc */ + /* set an upper boundary */ + newitr = min(newitr, 3000); + /* Be nice to the mid range */ + if ((newitr > 300) && (newitr < 1200)) + newitr = (newitr / 3); + else + newitr = (newitr / 2); + + /* The value above was written straight to EITR; make it a rate */ + newitr = EM_AIM_DIVIDEND / newitr; + + /* + * Cap the rate: enable_aim=1 is the normal setting, enable_aim=2 opts + * into the low latency end. The original was unbounded and would ask + * for ~95k ints/s on minimum sized frames. There is deliberately no + * floor, so jumbo traffic settles near 2.7k ints/s. + */ + if (sc->enable_aim == 1) + newitr = min(newitr, EM_INTS_20K); + else + newitr = min(newitr, EM_INTS_70K); + + return (newitr); +} + /********************************************************************* * * Helper to calculate next (E)ITR value for AIM @@ -1709,10 +1757,8 @@ em_newitr(struct e1000_softc *sc, struct em_rx_queue *que, { struct e1000_hw *hw = &sc->hw; struct em_tx_queue *tx_que; - u32 bytes, bytes_per_packet, packets; u32 ringbytes, ringpackets, rxbytes, rxpackets, txbytes, txpackets; u32 newitr; - u8 nextlatency; int i; em_aim_rx_delta(rxr, &rxbytes, &rxpackets); @@ -1736,108 +1782,22 @@ em_newitr(struct e1000_softc *sc, struct em_rx_queue *que, if (txbytes == 0 && rxbytes == 0) return; - newitr = 0; - - if (sc->enable_aim) { - nextlatency = rxr->rx_nextlatency; - + if (sc->enable_aim == 0) { + newitr = em_max_interrupt_rate; + } else if (sc->link_speed < SPEED_1000) { /* Use half default (4K) ITR if sub-gig */ - if (sc->link_speed < SPEED_1000) { - newitr = EM_INTS_4K; - goto em_set_next_itr; - } - /* Want at least enough packet buffer for two frames to AIM */ - if (sc->shared->isc_max_frame_size * 2 > (sc->pba << 10)) { - newitr = em_max_interrupt_rate; - goto em_set_next_itr; - } - - bytes = bytes_per_packet = packets = 0; - /* Get largest values from the associated tx and rx ring */ - if (txpackets != 0) { - bytes = txbytes; - bytes_per_packet = txbytes / txpackets; - packets = txpackets; - } - if (rxpackets != 0) { - bytes = lmax(bytes, rxbytes); - bytes_per_packet = - lmax(bytes_per_packet, rxbytes / rxpackets); - packets = lmax(packets, rxpackets); - } - - /* Latency state machine */ - switch (nextlatency) { - case itr_latency_disabled: /* Bootstrapping */ - nextlatency = itr_latency_low; - break; - case itr_latency_lowest: /* 70k ints/s */ - /* TSO and jumbo frames */ - if (bytes_per_packet > 8000) - nextlatency = itr_latency_bulk; - else if ((packets < 5) && (bytes > 512)) - nextlatency = itr_latency_low; - break; - case itr_latency_low: /* 20k ints/s */ - if (bytes > 10000) { - /* Handle TSO */ - if (bytes_per_packet > 8000) - nextlatency = itr_latency_bulk; - else if ((packets < 10) || - (bytes_per_packet > 1200)) - nextlatency = itr_latency_bulk; - else if (packets > 35) - nextlatency = itr_latency_lowest; - } else if (bytes_per_packet > 2000) { - nextlatency = itr_latency_bulk; - } else if (packets < 3 && bytes < 512) { - nextlatency = itr_latency_lowest; - } - break; - case itr_latency_bulk: /* 4k ints/s */ - if (bytes > 25000) { - if (packets > 35) - nextlatency = itr_latency_low; - } else if (bytes < 1500) - nextlatency = itr_latency_low; - break; - default: - nextlatency = itr_latency_low; - device_printf(sc->dev, - "Unexpected newitr transition %d\n", nextlatency); - break; - } - - /* Trim itr_latency_lowest for default AIM setting */ - if (sc->enable_aim == 1 && nextlatency == itr_latency_lowest) - nextlatency = itr_latency_low; - - /* Request new latency */ - rxr->rx_nextlatency = nextlatency; - } else { - /* We may have toggled to AIM disabled */ - nextlatency = itr_latency_disabled; - rxr->rx_nextlatency = nextlatency; - } - - /* ITR state machine */ - switch(nextlatency) { - case itr_latency_lowest: - newitr = EM_INTS_70K; - break; - case itr_latency_low: - newitr = EM_INTS_20K; - break; - case itr_latency_bulk: newitr = EM_INTS_4K; - break; - case itr_latency_disabled: - default: + } else if (sc->shared->isc_max_frame_size * 2 > (sc->pba << 10)) { + /* Want at least enough packet buffer for two frames to AIM */ newitr = em_max_interrupt_rate; - break; + } else { + newitr = em_ring_itr(sc, rxbytes, rxpackets, txbytes, + txpackets); + /* No usable observation; leave the rate where it is */ + if (newitr == 0) + return; } -em_set_next_itr: if (hw->mac.type >= igb_mac_min) { newitr = IGB_INTS_TO_EITR(newitr); diff --git a/sys/dev/e1000/if_em.h b/sys/dev/e1000/if_em.h index 594399498db3..9dfe23453428 100644 --- a/sys/dev/e1000/if_em.h +++ b/sys/dev/e1000/if_em.h @@ -258,6 +258,14 @@ #define IGB_EITR_TO_INTS(i) ((IGB_EITR_DIVIDEND << IGB_EITR_SHIFT) / \ ((i) & IGB_QVECTOR_MASK)) +/* + * The average packet size calculation in em_ring_itr() yields an EITR + * interval field value. That field is quarter microsecond granular (see + * IGB_EITR_SHIFT), so an interval of V is 1000000 / (V / 4) interrupts per + * second. + */ +#define EM_AIM_DIVIDEND (IGB_EITR_DIVIDEND << IGB_EITR_SHIFT) + #define IGB_LINK_ITR 2000 #define I210_LINK_DELAY 1000 @@ -476,9 +484,6 @@ struct rx_ring { uint64_t rx_aim_snapshot __aligned(8); u32 rx_packets_last; u32 rx_bytes_last; - - /* Next requested ITR latency */ - u8 rx_nextlatency; }; static __inline voidhome | help
Want to link to this message? Use this
URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?6a655c56.32e36.3041c7cc>