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Message-ID: <2839f04c-8d7b-b010-f7c4-540359037d38@gmail.com>
Date: Tue, 7 Sep 2021 08:03:14 +0200
From: Heiner Kallweit <hkallweit1@...il.com>
To: Kai-Heng Feng <kai.heng.feng@...onical.com>, nic_swsd@...ltek.com,
bhelgaas@...gle.com
Cc: davem@...emloft.net, kuba@...nel.org, anthony.wong@...onical.com,
netdev@...r.kernel.org, linux-pci@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [RFC] [PATCH net-next v4] [PATCH 2/2] r8169: Implement dynamic
ASPM mechanism
On 27.08.2021 19:14, Kai-Heng Feng wrote:
> r8169 NICs on some platforms have abysmal speed when ASPM is enabled.
> Same issue can be observed with older vendor drivers.
>
> The issue is however solved by the latest vendor driver. There's a new
> mechanism, which disables r8169's internal ASPM when the NIC traffic has
> more than 10 packets, and vice versa. The possible reason for this is
> likely because the buffer on the chip is too small for its ASPM exit
> latency.
>
> Realtek confirmed that all their PCIe LAN NICs, r8106, r8168 and r8125
> use dynamic ASPM under Windows. So implement the same mechanism here to
> resolve the issue.
>
> Because ASPM control may not be granted by BIOS while ASPM is enabled,
> remove aspm_manageable and use pcie_aspm_capable() instead. If BIOS
> enables ASPM for the device, we want to enable dynamic ASPM on it.
>
> In addition, since PCIe ASPM can be switched via sysfs, enable/disable
> dynamic ASPM accordingly by checking pcie_aspm_enabled().
>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> ---
> v4:
> - Squash two patches
> - Remove aspm_manageable and use pcie_aspm_capable()
> pcie_aspm_enabled() accordingly
>
> v3:
> - Use msecs_to_jiffies() for delay time
> - Use atomic_t instead of mutex for bh
> - Mention the buffer size and ASPM exit latency in commit message
>
> v2:
> - Use delayed_work instead of timer_list to avoid interrupt context
> - Use mutex to serialize packet counter read/write
> - Wording change
> drivers/net/ethernet/realtek/r8169_main.c | 77 ++++++++++++++++++++---
> 1 file changed, 69 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
> index 46a6ff9a782d7..97dba8f437b78 100644
> --- a/drivers/net/ethernet/realtek/r8169_main.c
> +++ b/drivers/net/ethernet/realtek/r8169_main.c
> @@ -623,7 +623,10 @@ struct rtl8169_private {
> } wk;
>
> unsigned supports_gmii:1;
> - unsigned aspm_manageable:1;
> + unsigned rtl_aspm_enabled:1;
> + struct delayed_work aspm_toggle;
> + atomic_t aspm_packet_count;
> +
> dma_addr_t counters_phys_addr;
> struct rtl8169_counters *counters;
> struct rtl8169_tc_offsets tc_offset;
> @@ -698,6 +701,20 @@ static bool rtl_is_8168evl_up(struct rtl8169_private *tp)
> tp->mac_version <= RTL_GIGA_MAC_VER_53;
> }
>
> +static int rtl_supports_aspm(struct rtl8169_private *tp)
> +{
> + switch (tp->mac_version) {
> + case RTL_GIGA_MAC_VER_02 ... RTL_GIGA_MAC_VER_31:
> + case RTL_GIGA_MAC_VER_37:
> + case RTL_GIGA_MAC_VER_39:
> + case RTL_GIGA_MAC_VER_43:
> + case RTL_GIGA_MAC_VER_47:
> + return 0;
> + default:
> + return 1;
> + }
Why is this needed now that you have pcie_aspm_capable()?
> +}
> +
> static bool rtl_supports_eee(struct rtl8169_private *tp)
> {
> return tp->mac_version >= RTL_GIGA_MAC_VER_34 &&
> @@ -2699,8 +2716,15 @@ static void rtl_enable_exit_l1(struct rtl8169_private *tp)
>
> static void rtl_hw_aspm_clkreq_enable(struct rtl8169_private *tp, bool enable)
> {
> + struct pci_dev *pdev = tp->pci_dev;
> +
> + if (!pcie_aspm_enabled(pdev) && enable)
> + return;
> +
> + tp->rtl_aspm_enabled = enable;
> +
> /* Don't enable ASPM in the chip if OS can't control ASPM */
> - if (enable && tp->aspm_manageable) {
> + if (enable) {
> RTL_W8(tp, Config5, RTL_R8(tp, Config5) | ASPM_en);
> RTL_W8(tp, Config2, RTL_R8(tp, Config2) | ClkReqEn);
> } else {
> @@ -4440,6 +4464,7 @@ static void rtl_tx(struct net_device *dev, struct rtl8169_private *tp,
>
> dirty_tx = tp->dirty_tx;
>
> + atomic_add(tp->cur_tx - dirty_tx, &tp->aspm_packet_count);
> while (READ_ONCE(tp->cur_tx) != dirty_tx) {
> unsigned int entry = dirty_tx % NUM_TX_DESC;
> u32 status;
> @@ -4584,6 +4609,8 @@ static int rtl_rx(struct net_device *dev, struct rtl8169_private *tp, int budget
> rtl8169_mark_to_asic(desc);
> }
>
> + atomic_add(count, &tp->aspm_packet_count);
> +
> return count;
> }
>
> @@ -4691,8 +4718,39 @@ static int r8169_phy_connect(struct rtl8169_private *tp)
> return 0;
> }
>
> +#define ASPM_PACKET_THRESHOLD 10
> +#define ASPM_TOGGLE_INTERVAL 1000
> +
> +static void rtl8169_aspm_toggle(struct work_struct *work)
> +{
> + struct rtl8169_private *tp = container_of(work, struct rtl8169_private,
> + aspm_toggle.work);
> + int packet_count;
> + bool enable;
> +
> + packet_count = atomic_xchg(&tp->aspm_packet_count, 0);
> +
> + if (pcie_aspm_enabled(tp->pci_dev)) {
> + enable = packet_count <= ASPM_PACKET_THRESHOLD;
> +
> + if (tp->rtl_aspm_enabled != enable) {
> + rtl_unlock_config_regs(tp);
This looks racy. Another unlock_config_regs/do_something/lock_config_regs
can run in parallel. And if such a parallel lock_config_regs is executed
exactly here, then rtl_hw_aspm_clkreq_enable() may fail.
> + rtl_hw_aspm_clkreq_enable(tp, enable);
> + rtl_lock_config_regs(tp);
> + }
> + } else if (tp->rtl_aspm_enabled) {
> + rtl_unlock_config_regs(tp);
> + rtl_hw_aspm_clkreq_enable(tp, false);
> + rtl_lock_config_regs(tp);
> + }
> +
> + schedule_delayed_work(&tp->aspm_toggle, msecs_to_jiffies(ASPM_TOGGLE_INTERVAL));
> +}
> +
> static void rtl8169_down(struct rtl8169_private *tp)
> {
> + cancel_delayed_work_sync(&tp->aspm_toggle);
> +
> /* Clear all task flags */
> bitmap_zero(tp->wk.flags, RTL_FLAG_MAX);
>
> @@ -4719,6 +4777,11 @@ static void rtl8169_up(struct rtl8169_private *tp)
> rtl_reset_work(tp);
>
> phy_start(tp->phydev);
> +
> + /* pcie_aspm_capable may change after system resume */
> + if (pcie_aspm_support_enabled() && pcie_aspm_capable(tp->pci_dev) &&
> + rtl_supports_aspm(tp))
> + schedule_delayed_work(&tp->aspm_toggle, 0);
> }
>
> static int rtl8169_close(struct net_device *dev)
> @@ -5306,12 +5369,6 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
> if (rc)
> return rc;
>
> - /* Disable ASPM L1 as that cause random device stop working
> - * problems as well as full system hangs for some PCIe devices users.
> - */
> - rc = pci_disable_link_state(pdev, PCIE_LINK_STATE_L1);
> - tp->aspm_manageable = !rc;
> -
> /* enable device (incl. PCI PM wakeup and hotplug setup) */
> rc = pcim_enable_device(pdev);
> if (rc < 0) {
> @@ -5378,6 +5435,10 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
>
> INIT_WORK(&tp->wk.work, rtl_task);
>
> + INIT_DELAYED_WORK(&tp->aspm_toggle, rtl8169_aspm_toggle);
> +
> + atomic_set(&tp->aspm_packet_count, 0);
> +
> rtl_init_mac_address(tp);
>
> dev->ethtool_ops = &rtl8169_ethtool_ops;
>
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