xref: /dpdk/doc/guides/cryptodevs/scheduler.rst (revision 4e30ead5e7ca886535e2b30632b2948d2aac1681)
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30
31Cryptodev Scheduler Poll Mode Driver Library
32============================================
33
34Scheduler PMD is a software crypto PMD, which has the capabilities of
35attaching hardware and/or software cryptodevs, and distributes ingress
36crypto ops among them in a certain manner.
37
38.. figure:: img/scheduler-overview.*
39
40   Cryptodev Scheduler Overview
41
42
43The Cryptodev Scheduler PMD library (**librte_pmd_crypto_scheduler**) acts as
44a software crypto PMD and shares the same API provided by librte_cryptodev.
45The PMD supports attaching multiple crypto PMDs, software or hardware, as
46slaves, and distributes the crypto workload to them with certain behavior.
47The behaviors are categorizes as different "modes". Basically, a scheduling
48mode defines certain actions for scheduling crypto ops to its slaves.
49
50The librte_pmd_crypto_scheduler library exports a C API which provides an API
51for attaching/detaching slaves, set/get scheduling modes, and enable/disable
52crypto ops reordering.
53
54Limitations
55-----------
56
57* Sessionless crypto operation is not supported
58* OOP crypto operation is not supported when the crypto op reordering feature
59  is enabled.
60
61
62Installation
63------------
64
65To build DPDK with CRYTPO_SCHEDULER_PMD the user is required to set
66CONFIG_RTE_LIBRTE_PMD_CRYPTO_SCHEDULER=y in config/common_base, and
67recompile DPDK
68
69
70Initialization
71--------------
72
73To use the PMD in an application, user must:
74
75* Call rte_eal_vdev_init("crpyto_scheduler") within the application.
76
77* Use --vdev="crpyto_scheduler" in the EAL options, which will call
78  rte_eal_vdev_init() internally.
79
80
81The following parameters (all optional) can be provided in the previous
82two calls:
83
84* socket_id: Specify the socket where the memory for the device is going
85  to be allocated (by default, socket_id will be the socket where the core
86  that is creating the PMD is running on).
87
88* max_nb_sessions: Specify the maximum number of sessions that can be
89  created. This value may be overwritten internally if there are too
90  many devices are attached.
91
92* slave: If a cryptodev has been initialized with specific name, it can be
93  attached to the scheduler using this parameter, simply filling the name
94  here. Multiple cryptodevs can be attached initially by presenting this
95  parameter multiple times.
96
97* mode: Specify the scheduling mode of the PMD. The supported scheduling
98  mode parameter values are specified in the "Cryptodev Scheduler Modes
99  Overview" section.
100
101* ordering: Specify the status of the crypto operations ordering feature.
102  The value of this parameter can be "enable" or "disable". This feature
103  is disabled by default.
104
105Example:
106
107.. code-block:: console
108
109    ... --vdev "crypto_aesni_mb_pmd,name=aesni_mb_1" --vdev "crypto_aesni_mb_pmd,name=aesni_mb_2" --vdev "crypto_scheduler_pmd,slave=aesni_mb_1,slave=aesni_mb_2" ...
110
111.. note::
112
113    * The scheduler cryptodev cannot be started unless the scheduling mode
114      is set and at least one slave is attached. Also, to configure the
115      scheduler in the run-time, like attach/detach slave(s), change
116      scheduling mode, or enable/disable crypto op ordering, one should stop
117      the scheduler first, otherwise an error will be returned.
118
119    * The crypto op reordering feature requires using the userdata field of
120      every mbuf to be processed to store temporary data. By the end of
121      processing, the field is set to pointing to NULL, any previously
122      stored value of this field will be lost.
123
124
125Cryptodev Scheduler Modes Overview
126----------------------------------
127
128Currently the Crypto Scheduler PMD library supports following modes of
129operation:
130
131*   **CDEV_SCHED_MODE_ROUNDROBIN:**
132
133   *Initialization mode parameter*: **round-robin**
134
135   Round-robin mode, which distributes the enqueued burst of crypto ops
136   among its slaves in a round-robin manner. This mode may help to fill
137   the throughput gap between the physical core and the existing cryptodevs
138   to increase the overall performance.
139
140*   **CDEV_SCHED_MODE_PKT_SIZE_DISTR:**
141
142   *Initialization mode parameter*: **packet-size-distr**
143
144   Packet-size based distribution mode, which works with 2 slaves, the primary
145   slave and the secondary slave, and distributes the enqueued crypto
146   operations to them based on their data lengths. A crypto operation will be
147   distributed to the primary slave if its data length is equal to or bigger
148   than the designated threshold, otherwise it will be handled by the secondary
149   slave.
150
151   A typical usecase in this mode is with the QAT cryptodev as the primary and
152   a software cryptodev as the secondary slave. This may help applications to
153   process additional crypto workload than what the QAT cryptodev can handle on
154   its own, by making use of the available CPU cycles to deal with smaller
155   crypto workloads.
156
157   The threshold is set to 128 bytes by default. It can be updated by calling
158   function **rte_cryptodev_scheduler_option_set**. The parameter of
159   **option_type** must be **CDEV_SCHED_OPTION_THRESHOLD** and **option** should
160   point to a rte_cryptodev_scheduler_threshold_option structure filled with
161   appropriate threshold value. Please NOTE this threshold has be a power-of-2
162   unsigned integer.
163
164*   **CDEV_SCHED_MODE_FAILOVER:**
165
166   *Initialization mode parameter*: **fail-over**
167
168   Fail-over mode, which works with 2 slaves, the primary slave and the
169   secondary slave. In this mode, the scheduler will enqueue the incoming
170   crypto operation burst to the primary slave. When one or more crypto
171   operations fail to be enqueued, then they will be enqueued to the secondary
172   slave.
173