Memory reservations done using the APIs provided by rte_malloc are also backed by pages from the hugetlbfs filesystem.
-Xen Dom0 support without hugetbls
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-The existing memory management implementation is based on the Linux kernel hugepage mechanism.
-However, Xen Dom0 does not support hugepages, so a new Linux kernel module rte_dom0_mm is added to workaround this limitation.
-
-The EAL uses IOCTL interface to notify the Linux kernel module rte_dom0_mm to allocate memory of specified size,
-and get all memory segments information from the module,
-and the EAL uses MMAP interface to map the allocated memory.
-For each memory segment, the physical addresses are contiguous within it but actual hardware addresses are contiguous within 2MB.
-
PCI Access
~~~~~~~~~~
CPU Feature Identification
~~~~~~~~~~~~~~~~~~~~~~~~~~
-The EAL can query the CPU at runtime (using the rte_cpu_get_feature() function) to determine which CPU features are available.
+The EAL can query the CPU at runtime (using the rte_cpu_get_features() function) to determine which CPU features are available.
User Space Interrupt Event
~~~~~~~~~~~~~~~~~~~~~~~~~~
.. note::
- In DPDK PMD, the only interrupts handled by the dedicated host thread are those for link status change,
- i.e. link up and link down notification.
+ In DPDK PMD, the only interrupts handled by the dedicated host thread are those for link status change
+ (link up and link down notification) and for sudden device removal.
+ RX Interrupt Event
The RX interrupt are controlled/enabled/disabled by ethdev APIs - 'rte_eth_dev_rx_intr_*'. They return failure if the PMD
hasn't support them yet. The intr_conf.rxq flag is used to turn on the capability of RX interrupt per device.
++ Device Removal Event
+
+This event is triggered by a device being removed at a bus level. Its
+underlying resources may have been made unavailable (i.e. PCI mappings
+unmapped). The PMD must make sure that on such occurrence, the application can
+still safely use its callbacks.
+
+This event can be subscribed to in the same way one would subscribe to a link
+status change event. The execution context is thus the same, i.e. it is the
+dedicated interrupt host thread.
+
+Considering this, it is likely that an application would want to close a
+device having emitted a Device Removal Event. In such case, calling
+``rte_eth_dev_close()`` can trigger it to unregister its own Device Removal Event
+callback. Care must be taken not to close the device from the interrupt handler
+context. It is necessary to reschedule such closing operation.
+
Blacklisting
~~~~~~~~~~~~
The rte_mempool uses a per-lcore cache inside the mempool.
For non-EAL pthreads, ``rte_lcore_id()`` will not return a valid number.
- So for now, when rte_mempool is used with non-EAL pthreads, the put/get operations will bypass the mempool cache and there is a performance penalty because of this bypass.
- Support for non-EAL mempool cache is currently being enabled.
+ So for now, when rte_mempool is used with non-EAL pthreads, the put/get operations will bypass the default mempool cache and there is a performance penalty because of this bypass.
+ Only user-owned external caches can be used in a non-EAL context in conjunction with ``rte_mempool_generic_put()`` and ``rte_mempool_generic_get()`` that accept an explicit cache parameter.
+ rte_ring
be preempted by another pthread doing a multi-consumer dequeue on
the same ring.
- Bypassing this constraint it may cause the 2nd pthread to spin until the 1st one is scheduled again.
+ Bypassing this constraint may cause the 2nd pthread to spin until the 1st one is scheduled again.
Moreover, if the 1st pthread is preempted by a context that has an higher priority, it may even cause a dead lock.
This does not mean it cannot be used, simply, there is a need to narrow down the situation when it is used by multi-pthread on the same core.
3. It MUST not be used by multi-producer/consumer pthreads, whose scheduling policies are SCHED_FIFO or SCHED_RR.
- ``RTE_RING_PAUSE_REP_COUNT`` is defined for rte_ring to reduce contention. It's mainly for case 2, a yield is issued after number of times pause repeat.
-
- It adds a sched_yield() syscall if the thread spins for too long while waiting on the other thread to finish its operations on the ring.
- This gives the preempted thread a chance to proceed and finish with the ring enqueue/dequeue operation.
-
+ rte_timer
Running ``rte_timer_manager()`` on a non-EAL pthread is not allowed. However, resetting/stopping the timer from a non-EAL pthread is allowed.
git.droids-corp.org / dpdk.git / blobdiff