From 2677010e7793451c20d895c477c4dc76f6e6a10e Mon Sep 17 00:00:00 2001 From: Samiullah Khawaja Date: Thu, 10 Jul 2025 21:12:03 +0000 Subject: [PATCH] Add support to set NAPI threaded for individual NAPI A net device has a threaded sysctl that can be used to enable threaded NAPI polling on all of the NAPI contexts under that device. Allow enabling threaded NAPI polling at individual NAPI level using netlink. Extend the netlink operation `napi-set` and allow setting the threaded attribute of a NAPI. This will enable the threaded polling on a NAPI context. Add a test in `nl_netdev.py` that verifies various cases of threaded NAPI being set at NAPI and at device level. Tested ./tools/testing/selftests/net/nl_netdev.py TAP version 13 1..7 ok 1 nl_netdev.empty_check ok 2 nl_netdev.lo_check ok 3 nl_netdev.page_pool_check ok 4 nl_netdev.napi_list_check ok 5 nl_netdev.dev_set_threaded ok 6 nl_netdev.napi_set_threaded ok 7 nl_netdev.nsim_rxq_reset_down # Totals: pass:7 fail:0 xfail:0 xpass:0 skip:0 error:0 Signed-off-by: Samiullah Khawaja Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20250710211203.3979655-1-skhawaja@google.com Signed-off-by: Jakub Kicinski --- Documentation/netlink/specs/netdev.yaml | 10 +++ Documentation/networking/napi.rst | 9 ++- include/linux/netdevice.h | 1 + include/uapi/linux/netdev.h | 1 + net/core/dev.c | 30 +++++++- net/core/dev.h | 7 ++ net/core/netdev-genl-gen.c | 5 +- net/core/netdev-genl.c | 14 ++++ tools/include/uapi/linux/netdev.h | 1 + tools/testing/selftests/net/nl_netdev.py | 91 +++++++++++++++++++++++- 10 files changed, 162 insertions(+), 7 deletions(-) diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlink/specs/netdev.yaml index ce4cfec82100..85d0ea6ac426 100644 --- a/Documentation/netlink/specs/netdev.yaml +++ b/Documentation/netlink/specs/netdev.yaml @@ -283,6 +283,14 @@ attribute-sets: doc: The timeout, in nanoseconds, of how long to suspend irq processing, if event polling finds events type: uint + - + name: threaded + doc: Whether the NAPI is configured to operate in threaded polling + mode. If this is set to 1 then the NAPI context operates in + threaded polling mode. + type: uint + checks: + max: 1 - name: xsk-info attributes: [] @@ -694,6 +702,7 @@ operations: - defer-hard-irqs - gro-flush-timeout - irq-suspend-timeout + - threaded dump: request: attributes: @@ -746,6 +755,7 @@ operations: - defer-hard-irqs - gro-flush-timeout - irq-suspend-timeout + - threaded - name: bind-tx doc: Bind dmabuf to netdev for TX diff --git a/Documentation/networking/napi.rst b/Documentation/networking/napi.rst index d0e3953cae6a..a15754adb041 100644 --- a/Documentation/networking/napi.rst +++ b/Documentation/networking/napi.rst @@ -444,7 +444,14 @@ dependent). The NAPI instance IDs will be assigned in the opposite order than the process IDs of the kernel threads. Threaded NAPI is controlled by writing 0/1 to the ``threaded`` file in -netdev's sysfs directory. +netdev's sysfs directory. It can also be enabled for a specific NAPI using +netlink interface. + +For example, using the script: + +.. code-block:: bash + + $ ynl --family netdev --do napi-set --json='{"id": 66, "threaded": 1}' .. rubric:: Footnotes diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index ec23cee5245d..e49d8c98d284 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -369,6 +369,7 @@ struct napi_config { u64 irq_suspend_timeout; u32 defer_hard_irqs; cpumask_t affinity_mask; + bool threaded; unsigned int napi_id; }; diff --git a/include/uapi/linux/netdev.h b/include/uapi/linux/netdev.h index 7eb9571786b8..1f3719a9a0eb 100644 --- a/include/uapi/linux/netdev.h +++ b/include/uapi/linux/netdev.h @@ -134,6 +134,7 @@ enum { NETDEV_A_NAPI_DEFER_HARD_IRQS, NETDEV_A_NAPI_GRO_FLUSH_TIMEOUT, NETDEV_A_NAPI_IRQ_SUSPEND_TIMEOUT, + NETDEV_A_NAPI_THREADED, __NETDEV_A_NAPI_MAX, NETDEV_A_NAPI_MAX = (__NETDEV_A_NAPI_MAX - 1) diff --git a/net/core/dev.c b/net/core/dev.c index 19ddc3e6990a..621a639aeba1 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6961,6 +6961,31 @@ static void napi_stop_kthread(struct napi_struct *napi) napi->thread = NULL; } +int napi_set_threaded(struct napi_struct *napi, bool threaded) +{ + if (threaded) { + if (!napi->thread) { + int err = napi_kthread_create(napi); + + if (err) + return err; + } + } + + if (napi->config) + napi->config->threaded = threaded; + + if (!threaded && napi->thread) { + napi_stop_kthread(napi); + } else { + /* Make sure kthread is created before THREADED bit is set. */ + smp_mb__before_atomic(); + assign_bit(NAPI_STATE_THREADED, &napi->state, threaded); + } + + return 0; +} + int dev_set_threaded(struct net_device *dev, bool threaded) { struct napi_struct *napi; @@ -6968,9 +6993,6 @@ int dev_set_threaded(struct net_device *dev, bool threaded) netdev_assert_locked_or_invisible(dev); - if (dev->threaded == threaded) - return 0; - if (threaded) { list_for_each_entry(napi, &dev->napi_list, dev_list) { if (!napi->thread) { @@ -7221,6 +7243,8 @@ static void napi_restore_config(struct napi_struct *n) napi_hash_add(n); n->config->napi_id = n->napi_id; } + + WARN_ON_ONCE(napi_set_threaded(n, n->config->threaded)); } static void napi_save_config(struct napi_struct *n) diff --git a/net/core/dev.h b/net/core/dev.h index e93f36b7ddf3..a603387fb566 100644 --- a/net/core/dev.h +++ b/net/core/dev.h @@ -315,6 +315,13 @@ static inline void napi_set_irq_suspend_timeout(struct napi_struct *n, WRITE_ONCE(n->irq_suspend_timeout, timeout); } +static inline bool napi_get_threaded(struct napi_struct *n) +{ + return test_bit(NAPI_STATE_THREADED, &n->state); +} + +int napi_set_threaded(struct napi_struct *n, bool threaded); + int rps_cpumask_housekeeping(struct cpumask *mask); #if defined(CONFIG_DEBUG_NET) && defined(CONFIG_BPF_SYSCALL) diff --git a/net/core/netdev-genl-gen.c b/net/core/netdev-genl-gen.c index 4fc44587f493..0994bd68a7e6 100644 --- a/net/core/netdev-genl-gen.c +++ b/net/core/netdev-genl-gen.c @@ -92,11 +92,12 @@ static const struct nla_policy netdev_bind_rx_nl_policy[NETDEV_A_DMABUF_FD + 1] }; /* NETDEV_CMD_NAPI_SET - do */ -static const struct nla_policy netdev_napi_set_nl_policy[NETDEV_A_NAPI_IRQ_SUSPEND_TIMEOUT + 1] = { +static const struct nla_policy netdev_napi_set_nl_policy[NETDEV_A_NAPI_THREADED + 1] = { [NETDEV_A_NAPI_ID] = { .type = NLA_U32, }, [NETDEV_A_NAPI_DEFER_HARD_IRQS] = NLA_POLICY_FULL_RANGE(NLA_U32, &netdev_a_napi_defer_hard_irqs_range), [NETDEV_A_NAPI_GRO_FLUSH_TIMEOUT] = { .type = NLA_UINT, }, [NETDEV_A_NAPI_IRQ_SUSPEND_TIMEOUT] = { .type = NLA_UINT, }, + [NETDEV_A_NAPI_THREADED] = NLA_POLICY_MAX(NLA_UINT, 1), }; /* NETDEV_CMD_BIND_TX - do */ @@ -193,7 +194,7 @@ static const struct genl_split_ops netdev_nl_ops[] = { .cmd = NETDEV_CMD_NAPI_SET, .doit = netdev_nl_napi_set_doit, .policy = netdev_napi_set_nl_policy, - .maxattr = NETDEV_A_NAPI_IRQ_SUSPEND_TIMEOUT, + .maxattr = NETDEV_A_NAPI_THREADED, .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DO, }, { diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c index 2afa7b2141aa..5875df372415 100644 --- a/net/core/netdev-genl.c +++ b/net/core/netdev-genl.c @@ -184,6 +184,10 @@ netdev_nl_napi_fill_one(struct sk_buff *rsp, struct napi_struct *napi, if (napi->irq >= 0 && nla_put_u32(rsp, NETDEV_A_NAPI_IRQ, napi->irq)) goto nla_put_failure; + if (nla_put_uint(rsp, NETDEV_A_NAPI_THREADED, + napi_get_threaded(napi))) + goto nla_put_failure; + if (napi->thread) { pid = task_pid_nr(napi->thread); if (nla_put_u32(rsp, NETDEV_A_NAPI_PID, pid)) @@ -322,8 +326,18 @@ netdev_nl_napi_set_config(struct napi_struct *napi, struct genl_info *info) { u64 irq_suspend_timeout = 0; u64 gro_flush_timeout = 0; + u8 threaded = 0; u32 defer = 0; + if (info->attrs[NETDEV_A_NAPI_THREADED]) { + int ret; + + threaded = nla_get_uint(info->attrs[NETDEV_A_NAPI_THREADED]); + ret = napi_set_threaded(napi, !!threaded); + if (ret) + return ret; + } + if (info->attrs[NETDEV_A_NAPI_DEFER_HARD_IRQS]) { defer = nla_get_u32(info->attrs[NETDEV_A_NAPI_DEFER_HARD_IRQS]); napi_set_defer_hard_irqs(napi, defer); diff --git a/tools/include/uapi/linux/netdev.h b/tools/include/uapi/linux/netdev.h index 7eb9571786b8..1f3719a9a0eb 100644 --- a/tools/include/uapi/linux/netdev.h +++ b/tools/include/uapi/linux/netdev.h @@ -134,6 +134,7 @@ enum { NETDEV_A_NAPI_DEFER_HARD_IRQS, NETDEV_A_NAPI_GRO_FLUSH_TIMEOUT, NETDEV_A_NAPI_IRQ_SUSPEND_TIMEOUT, + NETDEV_A_NAPI_THREADED, __NETDEV_A_NAPI_MAX, NETDEV_A_NAPI_MAX = (__NETDEV_A_NAPI_MAX - 1) diff --git a/tools/testing/selftests/net/nl_netdev.py b/tools/testing/selftests/net/nl_netdev.py index c9109627a741..c8ffade79a52 100755 --- a/tools/testing/selftests/net/nl_netdev.py +++ b/tools/testing/selftests/net/nl_netdev.py @@ -35,6 +35,91 @@ def napi_list_check(nf) -> None: ksft_eq(len(napis), 100, comment=f"queue count after reset queue {q} mode {i}") +def napi_set_threaded(nf) -> None: + """ + Test that verifies various cases of napi threaded + set and unset at napi and device level. + """ + with NetdevSimDev(queue_count=2) as nsimdev: + nsim = nsimdev.nsims[0] + + ip(f"link set dev {nsim.ifname} up") + + napis = nf.napi_get({'ifindex': nsim.ifindex}, dump=True) + ksft_eq(len(napis), 2) + + napi0_id = napis[0]['id'] + napi1_id = napis[1]['id'] + + # set napi threaded and verify + nf.napi_set({'id': napi0_id, 'threaded': 1}) + napi0 = nf.napi_get({'id': napi0_id}) + ksft_eq(napi0['threaded'], 1) + ksft_ne(napi0.get('pid'), None) + + # check it is not set for napi1 + napi1 = nf.napi_get({'id': napi1_id}) + ksft_eq(napi1['threaded'], 0) + ksft_eq(napi1.get('pid'), None) + + ip(f"link set dev {nsim.ifname} down") + ip(f"link set dev {nsim.ifname} up") + + # verify if napi threaded is still set + napi0 = nf.napi_get({'id': napi0_id}) + ksft_eq(napi0['threaded'], 1) + ksft_ne(napi0.get('pid'), None) + + # check it is still not set for napi1 + napi1 = nf.napi_get({'id': napi1_id}) + ksft_eq(napi1['threaded'], 0) + ksft_eq(napi1.get('pid'), None) + + # unset napi threaded and verify + nf.napi_set({'id': napi0_id, 'threaded': 0}) + napi0 = nf.napi_get({'id': napi0_id}) + ksft_eq(napi0['threaded'], 0) + ksft_eq(napi0.get('pid'), None) + + # set threaded at device level + system(f"echo 1 > /sys/class/net/{nsim.ifname}/threaded") + + # check napi threaded is set for both napis + napi0 = nf.napi_get({'id': napi0_id}) + ksft_eq(napi0['threaded'], 1) + ksft_ne(napi0.get('pid'), None) + napi1 = nf.napi_get({'id': napi1_id}) + ksft_eq(napi1['threaded'], 1) + ksft_ne(napi1.get('pid'), None) + + # unset threaded at device level + system(f"echo 0 > /sys/class/net/{nsim.ifname}/threaded") + + # check napi threaded is unset for both napis + napi0 = nf.napi_get({'id': napi0_id}) + ksft_eq(napi0['threaded'], 0) + ksft_eq(napi0.get('pid'), None) + napi1 = nf.napi_get({'id': napi1_id}) + ksft_eq(napi1['threaded'], 0) + ksft_eq(napi1.get('pid'), None) + + # set napi threaded for napi0 + nf.napi_set({'id': napi0_id, 'threaded': 1}) + napi0 = nf.napi_get({'id': napi0_id}) + ksft_eq(napi0['threaded'], 1) + ksft_ne(napi0.get('pid'), None) + + # unset threaded at device level + system(f"echo 0 > /sys/class/net/{nsim.ifname}/threaded") + + # check napi threaded is unset for both napis + napi0 = nf.napi_get({'id': napi0_id}) + ksft_eq(napi0['threaded'], 0) + ksft_eq(napi0.get('pid'), None) + napi1 = nf.napi_get({'id': napi1_id}) + ksft_eq(napi1['threaded'], 0) + ksft_eq(napi1.get('pid'), None) + def dev_set_threaded(nf) -> None: """ Test that verifies various cases of napi threaded @@ -56,8 +141,10 @@ def dev_set_threaded(nf) -> None: # check napi threaded is set for both napis napi0 = nf.napi_get({'id': napi0_id}) + ksft_eq(napi0['threaded'], 1) ksft_ne(napi0.get('pid'), None) napi1 = nf.napi_get({'id': napi1_id}) + ksft_eq(napi1['threaded'], 1) ksft_ne(napi1.get('pid'), None) # unset threaded @@ -65,8 +152,10 @@ def dev_set_threaded(nf) -> None: # check napi threaded is unset for both napis napi0 = nf.napi_get({'id': napi0_id}) + ksft_eq(napi0['threaded'], 0) ksft_eq(napi0.get('pid'), None) napi1 = nf.napi_get({'id': napi1_id}) + ksft_eq(napi1['threaded'], 0) ksft_eq(napi1.get('pid'), None) def nsim_rxq_reset_down(nf) -> None: @@ -156,7 +245,7 @@ def page_pool_check(nf) -> None: def main() -> None: nf = NetdevFamily() ksft_run([empty_check, lo_check, page_pool_check, napi_list_check, - dev_set_threaded, nsim_rxq_reset_down], + dev_set_threaded, napi_set_threaded, nsim_rxq_reset_down], args=(nf, )) ksft_exit() -- 2.47.2