Implement stress option framework.

[sliver-openvswitch.git] / lib / stress.h

diff --git a/lib/stress.h b/lib/stress.h
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+/*
+ * Copyright (c) 2010 Nicira Networks.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef STRESS_H
+#define STRESS_H 1
+
+#include <stdbool.h>
+
+struct stress_option {
+    /* Properties. */
+    char *name;                 /* Short identifier string */
+    char *description;          /* Description of what the option stresses. */
+    unsigned int recommended;   /* Recommended period. */
+    unsigned int min;           /* Minimum period that can be set. */
+    unsigned int max;           /* Maximum period that can be set. */
+    unsigned int def;           /* Default value. */
+
+    /* Configuration. */
+    unsigned int period;        /* Desired period for firing, 0 to disable. */
+    bool random;                /* Fire randomly or exactly at period? */
+
+    /* State. */
+    unsigned int counter;       /* Number of hits before next firing. */
+    unsigned long long int hits; /* Hits since last reset. */
+};
+
+/* Creates and initializes a global instance of a stress option.
+ *
+ * NAME is a single word descriptive identifier for the option.  This is the
+ * token to pass in to the STRESS() macro at the sites where exectution is to
+ * be controlled by the option.
+ *
+ * DESCRIPTION is a quoted string that should describe to a person unfamiliar
+ * with the detailed internals of the code what behavior the option affects.
+ *
+ * RECOMMENDED is a suggested value for a person unfamiliar with the internals.
+ * It should put reasonable stress on the system without crippling it.
+ *
+ * MIN and MAX are the minimum and maximum values allowed for the option.
+ *
+ * DEFAULT is the default value for the option.  Specify 0 to disable the
+ * option by default, which should be the usual choice.  But some options can
+ * be left on at low levels without noticable impact to the end user.  An
+ * example would be failing to allocate a buffer for every 100000th packet
+ * processed by the system.
+ */
+#if USE_LINKER_SECTIONS
+#define STRESS_OPTION(NAME, DESCRIPTION, RECOMMENDED, MIN, MAX, DEFAULT) \
+        STRESS_OPTION__(NAME, DESCRIPTION, RECOMMENDED, MIN, MAX, DEFAULT); \
+        struct stress_option *stress_option_ptr_##NAME                  \
+            __attribute__((section("stress_options"))) = &stress_##NAME
+#else
+#define STRESS_OPTION(NAME, DESCRIPTION, RECOMMENDED, MIN, MAX, DEFAULT) \
+        extern struct stress_option stress_##NAME
+#endif
+
+/* Yields true if stress option NAME should be triggered,
+ * false otherwise. */
+#define STRESS(NAME) stress_sample__(&stress_##NAME)
+
+void stress_init_command(void);
+\f
+/* Implementation details. */
+
+#define STRESS_OPTION__(NAME, DESCRIPTION, RECOMMENDED, MIN, MAX, DEFAULT) \
+        struct stress_option stress_##NAME =                            \
+        { #NAME, DESCRIPTION, RECOMMENDED, MIN, MAX, DEFAULT,           \
+          DEFAULT ? DEFAULT : 0,                /* period */            \
+          false,                                /* random */            \
+          UINT_MAX,                             /* counter */           \
+          0 }                                   /* hits */
+
+bool stress_sample_slowpath__(struct stress_option *);
+static inline bool stress_sample__(struct stress_option *option)
+{
+    return --option->counter == 0 && stress_sample_slowpath__(option);
+}
+
+#endif /* STRESS_H */