lib/stress.h

   1 /*
   2  * Copyright (c) 2010, 2011 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #ifndef STRESS_H
  18 #define STRESS_H 1
  19
  20 #include <stdbool.h>
  21
  22 struct stress_option {
  23     /* Properties. */
  24     char *name;                 /* Short identifier string */
  25     char *description;          /* Description of what the option stresses. */
  26     unsigned int recommended;   /* Recommended period. */
  27     unsigned int min;           /* Minimum period that can be set. */
  28     unsigned int max;           /* Maximum period that can be set. */
  29     unsigned int def;           /* Default value. */
  30
  31     /* Configuration. */
  32     unsigned int period;        /* Desired period for firing, 0 to disable. */
  33     bool random;                /* Fire randomly or exactly at period? */
  34
  35     /* State. */
  36     unsigned int counter;       /* Number of hits before next firing. */
  37     unsigned long long int hits; /* Hits since last reset. */
  38 };
  39
  40 /* Creates and initializes a global instance of a stress option.
  41  *
  42  * NAME is a single word descriptive identifier for the option.  This is the
  43  * token to pass in to the STRESS() macro at the sites where exectution is to
  44  * be controlled by the option.
  45  *
  46  * DESCRIPTION is a quoted string that should describe to a person unfamiliar
  47  * with the detailed internals of the code what behavior the option affects.
  48  *
  49  * RECOMMENDED is a suggested value for a person unfamiliar with the internals.
  50  * It should put reasonable stress on the system without crippling it.
  51  *
  52  * MIN and MAX are the minimum and maximum values allowed for the option.
  53  *
  54  * DEFAULT is the default value for the option.  Specify 0 to disable the
  55  * option by default, which should be the usual choice.  But some options can
  56  * be left on at low levels without noticable impact to the end user.  An
  57  * example would be failing to allocate a buffer for every 100000th packet
  58  * processed by the system.
  59  */
  60 #if USE_LINKER_SECTIONS
  61 #define STRESS_OPTION(NAME, DESCRIPTION, RECOMMENDED, MIN, MAX, DEFAULT) \
  62         STRESS_OPTION__(NAME, DESCRIPTION, RECOMMENDED, MIN, MAX, DEFAULT); \
  63         extern struct stress_option *stress_option_ptr_##NAME;          \
  64         struct stress_option *stress_option_ptr_##NAME                  \
  65             __attribute__((section("stress_options"))) = &stress_##NAME
  66 #else
  67 #define STRESS_OPTION(NAME, DESCRIPTION, RECOMMENDED, MIN, MAX, DEFAULT) \
  68         extern struct stress_option stress_##NAME
  69 #endif
  70
  71 /* Yields true if stress option NAME should be triggered,
  72  * false otherwise. */
  73 #define STRESS(NAME) stress_sample__(&stress_##NAME)
  74
  75 void stress_init_command(void);
  76 \f
  77 /* Implementation details. */
  78
  79 #define STRESS_OPTION__(NAME, DESCRIPTION, RECOMMENDED, MIN, MAX, DEFAULT) \
  80         extern struct stress_option stress_##NAME;                      \
  81         struct stress_option stress_##NAME =                            \
  82         { #NAME, DESCRIPTION, RECOMMENDED, MIN, MAX, DEFAULT,           \
  83           DEFAULT ? DEFAULT : 0,                /* period */            \
  84           false,                                /* random */            \
  85           UINT_MAX,                             /* counter */           \
  86           0 }                                   /* hits */
  87
  88 bool stress_sample_slowpath__(struct stress_option *);
  89 static inline bool stress_sample__(struct stress_option *option)
  90 {
  91     return --option->counter == 0 && stress_sample_slowpath__(option);
  92 }
  93
  94 #endif /* STRESS_H */