2 * Copyright (c) 2016 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.
17 * vlib provides lock-free counters but those
18 * - Have 16bits per-CPU counter, which may overflow.
19 * - Would only increment.
21 * This is very similar to vlib counters, but may be used to count reference.
22 * Such a counter includes an arbitrary number of counters. Each counter
23 * is identified by its index. This is used to aggregate per-cpu memory.
26 * This reference counter is lock-free but is not race-condition free.
27 * The counting result is approximate and another mechanism needs to be used
28 * in order to ensure that an object may be freed.
32 #include <vnet/vnet.h>
33 #include <vppinfra/lock.h>
37 * A specific reference counter is used. The design is quite
38 * similar to vlib counters but:
39 * - It is possible to decrease the value
40 * - Summing will not zero the per-thread counters
41 * - Only the thread can reallocate its own counters vector (to avoid concurrency issues)
45 clib_spinlock_t counter_lock;
46 CLIB_CACHE_LINE_ALIGN_MARK(o);
47 } vlib_refcount_per_cpu_t;
50 vlib_refcount_per_cpu_t *per_cpu;
54 void vlib_refcount_lock (clib_spinlock_t counter_lock)
56 clib_spinlock_lock (&counter_lock);
60 void vlib_refcount_unlock (clib_spinlock_t counter_lock)
62 clib_spinlock_unlock (&counter_lock);
65 void __vlib_refcount_resize(vlib_refcount_per_cpu_t *per_cpu, u32 size);
68 void vlib_refcount_add(vlib_refcount_t *r, u32 thread_index, u32 counter_index, i32 v)
70 vlib_refcount_per_cpu_t *per_cpu = &r->per_cpu[thread_index];
71 if (PREDICT_FALSE(counter_index >= vec_len(per_cpu->counters)))
72 __vlib_refcount_resize(per_cpu, clib_max(counter_index + 16,(vec_len(per_cpu->counters)) * 2));
74 per_cpu->counters[counter_index] += v;
77 u64 vlib_refcount_get(vlib_refcount_t *r, u32 index);
80 void vlib_refcount_init(vlib_refcount_t *r)
82 vlib_thread_main_t *tm = vlib_get_thread_main ();
85 vec_validate (r->per_cpu, tm->n_vlib_mains - 1);
87 for (thread_index = 0; thread_index < tm->n_vlib_mains; thread_index++)
89 clib_spinlock_init (&r->per_cpu[thread_index].counter_lock);