[PATCH iwl-next v6 2/2] i40e: add devlink parameter for Flow Director ATR sample rate
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From: <hidden>
Date: 2026-10-11 13:50:27
Also in:
intel-wired-lan
Subsystem:
documentation, intel ethernet drivers, networking drivers, networking [general], the rest · Maintainers:
Jonathan Corbet, Tony Nguyen, Przemek Kitszel, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: Mohammad Heib <redacted> The i40e driver uses Flow Director ATR to periodically update flow steering information for active TCP flows. The update frequency is currently controlled by I40E_DEFAULT_ATR_SAMPLE_RATE and is fixed at driver build time. On systems with a large number of queues and high-rate TCP workloads, the default sampling interval can result in frequent Flow Director reprogramming for long-lived flows. The amount of TCP packet reordering observed on some systems is sensitive to the ATR sampling interval. Increasing the interval reduces Flow Director programming activity and can significantly reduce the associated reordering. Since the optimal sampling interval depends on the workload and system configuration, a single fixed value is not suitable for all deployments. Add a devlink parameter to allow administrators to tune the ATR sample rate at runtime without rebuilding the driver or disabling ATR functionality entirely. Signed-off-by: Mohammad Heib <redacted> --- Documentation/networking/devlink/i40e.rst | 21 +++++++++ .../net/ethernet/intel/i40e/i40e_devlink.c | 46 +++++++++++++++++++ 2 files changed, 67 insertions(+)
diff --git a/Documentation/networking/devlink/i40e.rst b/Documentation/networking/devlink/i40e.rst
index 51c887f0dc83..d280c17fe987 100644
--- a/Documentation/networking/devlink/i40e.rst
+++ b/Documentation/networking/devlink/i40e.rst@@ -40,6 +40,27 @@ Parameters The default value is ``0`` (internal calculation is used). +.. list-table:: Driver specific parameters implemented + :widths: 5 5 90 + + * - Name + - Mode + - Notes + * - ``atr_sample_rate`` + - runtime + - Controls how frequently Flow Director ATR updates flow steering + information for active TCP flows. + + ATR programs Flow Director entries based on sampled TCP packets + per Tx queue. The sampling interval is the number of TCP packets + transmitted on each queue between ATR updates. + + Lower values increase Flow Director programming activity, while + higher values reduce the update frequency. + + Setting to ``0`` disables ATR sampling (no filters will be programmed). + + The default value is ``20``. Info versions =============
diff --git a/drivers/net/ethernet/intel/i40e/i40e_devlink.c b/drivers/net/ethernet/intel/i40e/i40e_devlink.c
index 229179ccc131..8af2487776f2 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_devlink.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_devlink.c@@ -33,12 +33,58 @@ static int i40e_max_mac_per_vf_get(struct devlink *devlink, return 0; } +static int i40e_atr_sample_rate_set(struct devlink *devlink, + u32 id, + struct devlink_param_gset_ctx *ctx, + struct netlink_ext_ack *extack) +{ + struct i40e_pf *pf = devlink_priv(devlink); + u32 sample_rate = ctx->val.vu32; + + WRITE_ONCE(pf->atr_sample_rate, sample_rate); + + /* Setting rate to 0 disables sampling but does not remove + * existing ATR entries. Flush them so stale filters do not + * persist on devices without HW ATR eviction. + */ + if (!sample_rate) { + set_bit(__I40E_FD_ATR_AUTO_DISABLED, pf->state); + set_bit(__I40E_FD_FLUSH_REQUESTED, pf->state); + } + + return 0; +} + +static int i40e_atr_sample_rate_get(struct devlink *devlink, + u32 id, + struct devlink_param_gset_ctx *ctx, + struct netlink_ext_ack *extack) +{ + struct i40e_pf *pf = devlink_priv(devlink); + + ctx->val.vu32 = READ_ONCE(pf->atr_sample_rate); + + return 0; +} + +enum i40e_dl_param_id { + I40E_DEVLINK_PARAM_ID_BASE = DEVLINK_PARAM_GENERIC_ID_MAX, + I40E_DEVLINK_PARAM_ID_ATR_SAMPLE_RATE, +}; + static const struct devlink_param i40e_dl_params[] = { DEVLINK_PARAM_GENERIC(MAX_MAC_PER_VF, BIT(DEVLINK_PARAM_CMODE_RUNTIME), i40e_max_mac_per_vf_get, i40e_max_mac_per_vf_set, NULL), + DEVLINK_PARAM_DRIVER(I40E_DEVLINK_PARAM_ID_ATR_SAMPLE_RATE, + "atr_sample_rate", + DEVLINK_PARAM_TYPE_U32, + BIT(DEVLINK_PARAM_CMODE_RUNTIME), + i40e_atr_sample_rate_get, + i40e_atr_sample_rate_set, + NULL), }; static void i40e_info_get_dsn(struct i40e_pf *pf, char *buf, size_t len)
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2.56.0