Lines Matching +full:auto +full:- +full:poll
1 .. SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
16 interrupts first (:ref:`busy polling<poll>`).
29 and the associated poll method. struct napi_struct holds the state
30 of the NAPI instance while the method is the driver-specific event
37 -----------
45 A disabled NAPI can't be scheduled and its poll method is guaranteed
55 ------------
57 napi_schedule() is the basic method of scheduling a NAPI poll.
62 Later, after NAPI is scheduled, the driver's poll method will be
64 argument - drivers can process completions for any number of Tx
69 packets driver can process in a single poll. Rx specific APIs like page
79 The poll method returns the amount of work done. If the driver still
81 the poll method should return exactly ``budget``. In that case,
86 processed) the poll method should call napi_complete_done()
96 or return ``budget - 1``.
101 -------------
104 of calls. The poll method may be called without the driver scheduling
106 it's not guaranteed that the poll method will be called, even
109 As mentioned in the :ref:`drv_ctrl` section - napi_disable() and subsequent
110 calls to the poll method only wait for the ownership of the instance
111 to be released, not for the poll method to exit. This means that
118 --------------------------
121 the NAPI instance - until NAPI polling finishes any further
125 to IRQ being auto-masked by the device) should use the napi_schedule_prep()
128 .. code-block:: c
130 if (napi_schedule_prep(&v->napi)) {
131 mydrv_mask_rxtx_irq(v->idx);
133 __napi_schedule(&v->napi);
138 .. code-block:: c
140 if (budget && napi_complete_done(&v->napi, work_done)) {
141 mydrv_unmask_rxtx_irq(v->idx);
142 return min(work_done, budget - 1);
151 -------------------------
156 abstraction without specific user-facing semantics. That said, most networking
182 -----------------------
195 The above parameters can also be set on a per-NAPI basis using netlink via
196 netdev-genl. When used with netlink and configured on a per-NAPI basis, the
198 ``gro-flush-timeout`` and ``napi-defer-hard-irqs``.
200 Per-NAPI configuration can be done programmatically in a user application
206 .. code-block:: bash
208 $ kernel-source/tools/net/ynl/pyynl/cli.py \
209 --spec Documentation/netlink/specs/netdev.yaml \
210 --do napi-set \
211 --json='{"id": 345,
212 "defer-hard-irqs": 111,
213 "gro-flush-timeout": 11111}'
215 Similarly, the parameter ``irq-suspend-timeout`` can be set using netlink
216 via netdev-genl. There is no global sysfs parameter for this value.
218 ``irq-suspend-timeout`` is used to determine how long an application can
220 which can be set on a per-epoll context basis with ``EPIOCSPARAMS`` ioctl.
225 ------------
237 epoll-based busy polling
238 ------------------------
258 loop waiting for events. This is a system-wide setting and will cause all
259 epoll-based applications to busy poll when they call epoll_wait. This may
260 not be desirable as many applications may not have the need to busy poll.
266 .. code-block:: c
278 ---------------
283 Very high request-per-second applications (especially routing/forwarding
292 if ``gro_flush_timeout`` passes without any busy poll call. For epoll-based
300 with the ``SO_BUSY_POLL_BUDGET`` socket option. For epoll-based busy polling
309 attempting to busy poll by device IRQs and softirq processing. This value
310 should be chosen carefully with these tradeoffs in mind. epoll-based busy
318 --------------
334 1. The per-NAPI config parameter ``irq-suspend-timeout`` should be set to the
343 2. The sysfs parameter or per-NAPI config parameters ``gro_flush_timeout``
345 to defer IRQs after busy poll has found no data.
354 userland, the ``irq-suspend-timeout`` is deferred and IRQs are disabled. This
361 It is expected that ``irq-suspend-timeout`` will be set to a value much larger
362 than ``gro_flush_timeout`` as ``irq-suspend-timeout`` should suspend IRQs for
370 irq-driven packet delivery. During busy periods, ``irq-suspend-timeout``
378 1) hardirq -> softirq -> napi poll; basic interrupt delivery
379 2) timer -> softirq -> napi poll; deferred irq processing
380 3) epoll -> busy-poll -> napi poll; busy looping
388 During busy periods, ``irq-suspend-timeout`` is used as timer in Loop 2,
395 the recommended usage, because otherwise setting ``irq-suspend-timeout``
401 -------------
407 thread (called ``napi/${ifc-name}-${napi-id}``).