173 lines
7.4 KiB
Plaintext
173 lines
7.4 KiB
Plaintext
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// SPDX-License-Identifier: GPL-2.0-only
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// Copyright (C) 2022-2023 Isovalent, Inc.
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digraph {
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node [colorscheme=accent4,style=filled] # Apply colorscheme to all nodes
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graph [splines=ortho, nodesep=1]
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subgraph cluster_key {
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label = "Key\n(locks held during operation)";
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rankdir = TB;
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remote_lock [shape=rectangle,fillcolor=4,label="remote CPU LRU lock"]
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hash_lock [shape=rectangle,fillcolor=3,label="hashtab lock"]
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lru_lock [shape=rectangle,fillcolor=2,label="LRU lock"]
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local_lock [shape=rectangle,fillcolor=1,label="local CPU LRU lock"]
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no_lock [shape=rectangle,label="no locks held"]
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}
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begin [shape=oval,label="begin\nbpf_map_update()"]
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// Nodes below with an 'fn_' prefix are roughly labeled by the C function
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// names that initiate the corresponding logic in kernel/bpf/bpf_lru_list.c.
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// Number suffixes and errno suffixes handle subsections of the corresponding
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// logic in the function as of the writing of this dot.
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// cf. __local_list_pop_free() / bpf_percpu_lru_pop_free()
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local_freelist_check [shape=diamond,fillcolor=1,
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label="Local freelist\nnode available?"];
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use_local_node [shape=rectangle,
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label="Use node owned\nby this CPU"]
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// cf. bpf_lru_pop_free()
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common_lru_check [shape=diamond,
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label="Map created with\ncommon LRU?\n(!BPF_F_NO_COMMON_LRU)"];
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fn_bpf_lru_list_pop_free_to_local [shape=rectangle,fillcolor=2,
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label="Flush local pending,
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Rotate Global list, move
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LOCAL_FREE_TARGET
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from global -> local"]
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// Also corresponds to:
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// fn__local_list_flush()
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// fn_bpf_lru_list_rotate()
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fn___bpf_lru_node_move_to_free[shape=diamond,fillcolor=2,
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label="Able to free\nLOCAL_FREE_TARGET\nnodes?"]
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fn___bpf_lru_list_shrink_inactive [shape=rectangle,fillcolor=3,
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label="Shrink inactive list
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up to remaining
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LOCAL_FREE_TARGET
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(global LRU -> local)"]
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fn___bpf_lru_list_shrink [shape=diamond,fillcolor=2,
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label="> 0 entries in\nlocal free list?"]
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fn___bpf_lru_list_shrink2 [shape=rectangle,fillcolor=2,
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label="Steal one node from
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inactive, or if empty,
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from active global list"]
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fn___bpf_lru_list_shrink3 [shape=rectangle,fillcolor=3,
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label="Try to remove\nnode from hashtab"]
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local_freelist_check2 [shape=diamond,label="Htab removal\nsuccessful?"]
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common_lru_check2 [shape=diamond,
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label="Map created with\ncommon LRU?\n(!BPF_F_NO_COMMON_LRU)"];
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subgraph cluster_remote_lock {
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label = "Iterate through CPUs\n(start from current)";
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style = dashed;
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rankdir=LR;
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local_freelist_check5 [shape=diamond,fillcolor=4,
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label="Steal a node from\nper-cpu freelist?"]
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local_freelist_check6 [shape=rectangle,fillcolor=4,
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label="Steal a node from
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(1) Unreferenced pending, or
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(2) Any pending node"]
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local_freelist_check7 [shape=rectangle,fillcolor=3,
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label="Try to remove\nnode from hashtab"]
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fn_htab_lru_map_update_elem [shape=diamond,
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label="Stole node\nfrom remote\nCPU?"]
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fn_htab_lru_map_update_elem2 [shape=diamond,label="Iterated\nall CPUs?"]
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// Also corresponds to:
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// use_local_node()
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// fn__local_list_pop_pending()
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}
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fn_bpf_lru_list_pop_free_to_local2 [shape=rectangle,
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label="Use node that was\nnot recently referenced"]
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local_freelist_check4 [shape=rectangle,
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label="Use node that was\nactively referenced\nin global list"]
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fn_htab_lru_map_update_elem_ENOMEM [shape=oval,label="return -ENOMEM"]
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fn_htab_lru_map_update_elem3 [shape=rectangle,
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label="Use node that was\nactively referenced\nin (another?) CPU's cache"]
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fn_htab_lru_map_update_elem4 [shape=rectangle,fillcolor=3,
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label="Update hashmap\nwith new element"]
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fn_htab_lru_map_update_elem5 [shape=oval,label="return 0"]
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fn_htab_lru_map_update_elem_EBUSY [shape=oval,label="return -EBUSY"]
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fn_htab_lru_map_update_elem_EEXIST [shape=oval,label="return -EEXIST"]
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fn_htab_lru_map_update_elem_ENOENT [shape=oval,label="return -ENOENT"]
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begin -> local_freelist_check
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local_freelist_check -> use_local_node [xlabel="Y"]
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local_freelist_check -> common_lru_check [xlabel="N"]
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common_lru_check -> fn_bpf_lru_list_pop_free_to_local [xlabel="Y"]
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common_lru_check -> fn___bpf_lru_list_shrink_inactive [xlabel="N"]
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fn_bpf_lru_list_pop_free_to_local -> fn___bpf_lru_node_move_to_free
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fn___bpf_lru_node_move_to_free ->
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fn_bpf_lru_list_pop_free_to_local2 [xlabel="Y"]
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fn___bpf_lru_node_move_to_free ->
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fn___bpf_lru_list_shrink_inactive [xlabel="N"]
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fn___bpf_lru_list_shrink_inactive -> fn___bpf_lru_list_shrink
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fn___bpf_lru_list_shrink -> fn_bpf_lru_list_pop_free_to_local2 [xlabel = "Y"]
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fn___bpf_lru_list_shrink -> fn___bpf_lru_list_shrink2 [xlabel="N"]
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fn___bpf_lru_list_shrink2 -> fn___bpf_lru_list_shrink3
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fn___bpf_lru_list_shrink3 -> local_freelist_check2
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local_freelist_check2 -> local_freelist_check4 [xlabel = "Y"]
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local_freelist_check2 -> common_lru_check2 [xlabel = "N"]
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common_lru_check2 -> local_freelist_check5 [xlabel = "Y"]
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common_lru_check2 -> fn_htab_lru_map_update_elem_ENOMEM [xlabel = "N"]
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local_freelist_check5 -> fn_htab_lru_map_update_elem [xlabel = "Y"]
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local_freelist_check5 -> local_freelist_check6 [xlabel = "N"]
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local_freelist_check6 -> local_freelist_check7
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local_freelist_check7 -> fn_htab_lru_map_update_elem
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fn_htab_lru_map_update_elem -> fn_htab_lru_map_update_elem3 [xlabel = "Y"]
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fn_htab_lru_map_update_elem -> fn_htab_lru_map_update_elem2 [xlabel = "N"]
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fn_htab_lru_map_update_elem2 ->
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fn_htab_lru_map_update_elem_ENOMEM [xlabel = "Y"]
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fn_htab_lru_map_update_elem2 -> local_freelist_check5 [xlabel = "N"]
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fn_htab_lru_map_update_elem3 -> fn_htab_lru_map_update_elem4
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use_local_node -> fn_htab_lru_map_update_elem4
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fn_bpf_lru_list_pop_free_to_local2 -> fn_htab_lru_map_update_elem4
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local_freelist_check4 -> fn_htab_lru_map_update_elem4
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fn_htab_lru_map_update_elem4 -> fn_htab_lru_map_update_elem5 [headlabel="Success"]
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fn_htab_lru_map_update_elem4 ->
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fn_htab_lru_map_update_elem_EBUSY [xlabel="Hashtab lock failed"]
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fn_htab_lru_map_update_elem4 ->
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fn_htab_lru_map_update_elem_EEXIST [xlabel="BPF_EXIST set and\nkey already exists"]
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fn_htab_lru_map_update_elem4 ->
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fn_htab_lru_map_update_elem_ENOENT [headlabel="BPF_NOEXIST set\nand no such entry"]
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// Create invisible pad nodes to line up various nodes
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pad0 [style=invis]
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pad1 [style=invis]
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pad2 [style=invis]
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pad3 [style=invis]
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pad4 [style=invis]
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// Line up the key with the top of the graph
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no_lock -> local_lock [style=invis]
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local_lock -> lru_lock [style=invis]
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lru_lock -> hash_lock [style=invis]
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hash_lock -> remote_lock [style=invis]
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remote_lock -> local_freelist_check5 [style=invis]
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remote_lock -> fn___bpf_lru_list_shrink [style=invis]
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// Line up return code nodes at the bottom of the graph
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fn_htab_lru_map_update_elem -> pad0 [style=invis]
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pad0 -> pad1 [style=invis]
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pad1 -> pad2 [style=invis]
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//pad2-> fn_htab_lru_map_update_elem_ENOMEM [style=invis]
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fn_htab_lru_map_update_elem4 -> pad3 [style=invis]
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pad3 -> fn_htab_lru_map_update_elem5 [style=invis]
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pad3 -> fn_htab_lru_map_update_elem_EBUSY [style=invis]
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pad3 -> fn_htab_lru_map_update_elem_EEXIST [style=invis]
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pad3 -> fn_htab_lru_map_update_elem_ENOENT [style=invis]
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// Reduce diagram width by forcing some nodes to appear above others
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local_freelist_check4 -> fn_htab_lru_map_update_elem3 [style=invis]
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common_lru_check2 -> pad4 [style=invis]
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pad4 -> local_freelist_check5 [style=invis]
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}
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