/* * Copyright (c) 2015 Cisco and/or its affiliates. * 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 included_clib_timing_wheel_h #define included_clib_timing_wheel_h #include <vppinfra/format.h> typedef struct { /* Time of this element in units cpu clock ticks relative to time base. 32 bits should be large enough for several kilo-seconds to elapse before we have to re-set time base. */ u32 cpu_time_relative_to_base; /* User data to store in this bin. */ u32 user_data; } timing_wheel_elt_t; /* Overflow wheel elements where time does not fit into 32 bits. */ typedef struct { /* Absolute time of this element. */ u64 cpu_time; /* User data to store in this bin. */ u32 user_data; u32 pad; } timing_wheel_overflow_elt_t; typedef struct { /* 2^M bits: 1 means vector is non-zero else zero. */ uword *occupancy_bitmap; /* 2^M element table of element vectors, one for each time bin. */ timing_wheel_elt_t **elts; } timing_wheel_level_t; typedef struct { /* Vector of refill counts per level. */ u64 *refills; /* Number of times cpu time base was rescaled. */ u64 cpu_time_base_advances; } timing_wheel_stats_t; typedef struct { /* Each bin is a power of two clock ticks (N) chosen so that 2^N >= min_sched_time. */ u8 log2_clocks_per_bin; /* Wheels are 2^M bins where 2^(N+M) >= max_sched_time. */ u8 log2_bins_per_wheel; /* N + M. */ u8 log2_clocks_per_wheel; /* Number of bits to use in cpu_time_relative_to_base field of timing_wheel_elt_t. */ u8 n_wheel_elt_time_bits; /* 2^M. */ u32 bins_per_wheel; /* 2^M - 1. */ u32 bins_per_wheel_mask; timing_wheel_level_t *levels; timing_wheel_overflow_elt_t *overflow_pool; /* Free list of element vector so we can recycle old allocated vectors. */ timing_wheel_elt_t **free_elt_vectors; timing_wheel_elt_t *unexpired_elts_pending_insert; /* Hash table of user data values which have been deleted but not yet re-inserted. */ uword *deleted_user_data_hash; /* Enable validation for debugging. */ u32 validate; /* Time index. Measures time in units of 2^N clock ticks from when wheel starts. */ u64 current_time_index; /* All times are 32 bit numbers relative to cpu_time_base. So, roughly every 2^(32 + N) clocks we'll need to subtract from all timing_wheel_elt_t times to make sure they never overflow. */ u64 cpu_time_base; /* When current_time_index is >= this we update cpu_time_base to avoid overflowing 32 bit cpu_time_relative_to_base in timing_wheel_elt_t. */ u64 time_index_next_cpu_time_base_update; /* Cached earliest element on wheel; 0 if not valid. */ u64 cached_min_cpu_time_on_wheel; f64 min_sched_time, max_sched_time, cpu_clocks_per_second; timing_wheel_stats_t stats; } timing_wheel_t; /* Initialization function. */ void timing_wheel_init (timing_wheel_t * w, u64 current_cpu_time, f64 cpu_clocks_per_second); /* Insert user data on wheel at given CPU time stamp. */ void timing_wheel_insert (timing_wheel_t * w, u64 insert_cpu_time, u32 user_data); /* Delete user data from wheel (until it is again inserted). */ void timing_wheel_delete (timing_wheel_t * w, u32 user_data); /* Advance wheel and return any expired user data in vector. If non-zero min_next_expiring_element_cpu_time will return a cpu time stamp before which there are guaranteed to be no elements in the current wheel. */ u32 *timing_wheel_advance (timing_wheel_t * w, u64 advance_cpu_time, u32 * expired_user_data, u64 * min_next_expiring_element_cpu_time); /* Returns absolute time in clock cycles of next expiring element. */ u64 timing_wheel_next_expiring_elt_time (timing_wheel_t * w); /* Format a timing wheel. */ format_function_t format_timing_wheel; /* Testing function to validate wheel. */ void timing_wheel_validate (timing_wheel_t * w); #endif /* included_clib_timing_wheel_h */ /* * fd.io coding-style-patch-verification: ON * * Local Variables: * eval: (c-set-style "gnu") * End: */