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Instead of having a common LRU list, this patch allows a percpu LRU list which can be selected by specifying a map attribute. The map attribute will be added in the later patch. While the common use case for LRU is #reads >> #updates, percpu LRU list allows bpf prog to absorb unusual #updates under pathological case (e.g. external traffic facing machine which could be under attack). Each percpu LRU is isolated from each other. The LRU nodes (including free nodes) cannot be moved across different LRU Lists. Here are the update performance comparison between common LRU list and percpu LRU list (the test code is at the last patch): [root@kerneltest003.31.prn1 ~]# for i in 1 4 8; do echo -n "$i cpus: "; \ ./map_perf_test 16 $i | awk '{r += $3}END{print r " updates"}'; done 1 cpus: 2934082 updates 4 cpus: 7391434 updates 8 cpus: 6500576 updates [root@kerneltest003.31.prn1 ~]# for i in 1 4 8; do echo -n "$i cpus: "; \ ./map_perf_test 32 $i | awk '{r += $3}END{printr " updates"}'; done 1 cpus: 2896553 updates 4 cpus: 9766395 updates 8 cpus: 17460553 updates Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
85 lines
2.2 KiB
C
85 lines
2.2 KiB
C
/* Copyright (c) 2016 Facebook
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#ifndef __BPF_LRU_LIST_H_
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#define __BPF_LRU_LIST_H_
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#include <linux/list.h>
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#include <linux/spinlock_types.h>
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#define NR_BPF_LRU_LIST_T (3)
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#define NR_BPF_LRU_LIST_COUNT (2)
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#define NR_BPF_LRU_LOCAL_LIST_T (2)
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#define BPF_LOCAL_LIST_T_OFFSET NR_BPF_LRU_LIST_T
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enum bpf_lru_list_type {
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BPF_LRU_LIST_T_ACTIVE,
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BPF_LRU_LIST_T_INACTIVE,
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BPF_LRU_LIST_T_FREE,
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BPF_LRU_LOCAL_LIST_T_FREE,
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BPF_LRU_LOCAL_LIST_T_PENDING,
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};
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struct bpf_lru_node {
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struct list_head list;
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u16 cpu;
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u8 type;
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u8 ref;
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};
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struct bpf_lru_list {
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struct list_head lists[NR_BPF_LRU_LIST_T];
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unsigned int counts[NR_BPF_LRU_LIST_COUNT];
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/* The next inacitve list rotation starts from here */
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struct list_head *next_inactive_rotation;
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raw_spinlock_t lock ____cacheline_aligned_in_smp;
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};
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struct bpf_lru_locallist {
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struct list_head lists[NR_BPF_LRU_LOCAL_LIST_T];
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u16 next_steal;
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raw_spinlock_t lock;
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};
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struct bpf_common_lru {
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struct bpf_lru_list lru_list;
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struct bpf_lru_locallist __percpu *local_list;
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};
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typedef bool (*del_from_htab_func)(void *arg, struct bpf_lru_node *node);
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struct bpf_lru {
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union {
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struct bpf_common_lru common_lru;
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struct bpf_lru_list __percpu *percpu_lru;
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};
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del_from_htab_func del_from_htab;
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void *del_arg;
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unsigned int hash_offset;
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unsigned int nr_scans;
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bool percpu;
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};
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static inline void bpf_lru_node_set_ref(struct bpf_lru_node *node)
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{
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/* ref is an approximation on access frequency. It does not
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* have to be very accurate. Hence, no protection is used.
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*/
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node->ref = 1;
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}
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int bpf_lru_init(struct bpf_lru *lru, bool percpu, u32 hash_offset,
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del_from_htab_func del_from_htab, void *delete_arg);
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void bpf_lru_populate(struct bpf_lru *lru, void *buf, u32 node_offset,
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u32 elem_size, u32 nr_elems);
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void bpf_lru_destroy(struct bpf_lru *lru);
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struct bpf_lru_node *bpf_lru_pop_free(struct bpf_lru *lru, u32 hash);
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void bpf_lru_push_free(struct bpf_lru *lru, struct bpf_lru_node *node);
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void bpf_lru_promote(struct bpf_lru *lru, struct bpf_lru_node *node);
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#endif
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