2 * Copyright (c) 2015 Cisco and/or its affiliates.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at:
7 * http://www.apache.org/licenses/LICENSE-2.0
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
15 #ifndef included_clib_timing_wheel_h
16 #define included_clib_timing_wheel_h
18 #include <vppinfra/format.h>
22 /* Time of this element in units cpu clock ticks relative to time
23 base. 32 bits should be large enough for serveral kilo-seconds
24 to elapse before we have to re-set time base. */
25 u32 cpu_time_relative_to_base;
27 /* User data to store in this bin. */
31 /* Overflow wheel elements where time does not fit into 32 bits. */
34 /* Absolute time of this element. */
37 /* User data to store in this bin. */
41 } timing_wheel_overflow_elt_t;
45 /* 2^M bits: 1 means vector is non-zero else zero. */
46 uword *occupancy_bitmap;
48 /* 2^M element table of element vectors, one for each time bin. */
49 timing_wheel_elt_t **elts;
50 } timing_wheel_level_t;
54 /* Vector of refill counts per level. */
57 /* Number of times cpu time base was rescaled. */
58 u64 cpu_time_base_advances;
59 } timing_wheel_stats_t;
63 /* Each bin is a power of two clock ticks (N)
64 chosen so that 2^N >= min_sched_time. */
65 u8 log2_clocks_per_bin;
67 /* Wheels are 2^M bins where 2^(N+M) >= max_sched_time. */
68 u8 log2_bins_per_wheel;
71 u8 log2_clocks_per_wheel;
73 /* Number of bits to use in cpu_time_relative_to_base field
74 of timing_wheel_elt_t. */
75 u8 n_wheel_elt_time_bits;
81 u32 bins_per_wheel_mask;
83 timing_wheel_level_t *levels;
85 timing_wheel_overflow_elt_t *overflow_pool;
87 /* Free list of element vector so we can recycle old allocated vectors. */
88 timing_wheel_elt_t **free_elt_vectors;
90 timing_wheel_elt_t *unexpired_elts_pending_insert;
92 /* Hash table of user data values which have been deleted but not yet re-inserted. */
93 uword *deleted_user_data_hash;
95 /* Enable validation for debugging. */
98 /* Time index. Measures time in units of 2^N clock ticks from
100 u64 current_time_index;
102 /* All times are 32 bit numbers relative to cpu_time_base.
103 So, roughly every 2^(32 + N) clocks we'll need to subtract from
104 all timing_wheel_elt_t times to make sure they never overflow. */
107 /* When current_time_index is >= this we update cpu_time_base
108 to avoid overflowing 32 bit cpu_time_relative_to_base
109 in timing_wheel_elt_t. */
110 u64 time_index_next_cpu_time_base_update;
112 /* Cached earliest element on wheel; 0 if not valid. */
113 u64 cached_min_cpu_time_on_wheel;
115 f64 min_sched_time, max_sched_time, cpu_clocks_per_second;
117 timing_wheel_stats_t stats;
120 /* Initialization function. */
121 void timing_wheel_init (timing_wheel_t * w,
122 u64 current_cpu_time, f64 cpu_clocks_per_second);
124 /* Insert user data on wheel at given CPU time stamp. */
125 void timing_wheel_insert (timing_wheel_t * w, u64 insert_cpu_time,
128 /* Delete user data from wheel (until it is again inserted). */
129 void timing_wheel_delete (timing_wheel_t * w, u32 user_data);
131 /* Advance wheel and return any expired user data in vector. If non-zero
132 min_next_expiring_element_cpu_time will return a cpu time stamp
133 before which there are guaranteed to be no elements in the current wheel. */
134 u32 *timing_wheel_advance (timing_wheel_t * w, u64 advance_cpu_time,
135 u32 * expired_user_data,
136 u64 * min_next_expiring_element_cpu_time);
138 /* Returns absolute time in clock cycles of next expiring element. */
139 u64 timing_wheel_next_expiring_elt_time (timing_wheel_t * w);
141 /* Format a timing wheel. */
142 format_function_t format_timing_wheel;
144 /* Testing function to validate wheel. */
145 void timing_wheel_validate (timing_wheel_t * w);
147 #endif /* included_clib_timing_wheel_h */
150 * fd.io coding-style-patch-verification: ON
153 * eval: (c-set-style "gnu")