Blame SOURCES/0038-json-echo-Speedup-seqnum_to_json.patch

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From 26c4f15080663a12006abf8539ebf28bb223e6d9 Mon Sep 17 00:00:00 2001
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From: Phil Sutter <psutter@redhat.com>
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Date: Mon, 7 Dec 2020 18:29:15 +0100
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Subject: [PATCH] json: echo: Speedup seqnum_to_json()
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1900565
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Upstream Status: nftables commit 389a0e1edc89a
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commit 389a0e1edc89a4048a272e569d3349b1d43bc567
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Author: Phil Sutter <phil@nwl.cc>
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Date:   Fri Nov 20 20:01:59 2020 +0100
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    json: echo: Speedup seqnum_to_json()
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    Derek Dai reports:
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    "If there are a lot of command in JSON node, seqnum_to_json() will slow
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    down application (eg: firewalld) dramatically since it iterate whole
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    command list every time."
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    He sent a patch implementing a lookup table, but we can do better: Speed
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    this up by introducing a hash table to store the struct json_cmd_assoc
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    objects in, taking their netlink sequence number as key.
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    Quickly tested restoring a ruleset containing about 19k rules:
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    | # time ./before/nft -jeaf large_ruleset.json >/dev/null
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    | 4.85user 0.47system 0:05.48elapsed 97%CPU (0avgtext+0avgdata 69732maxresident)k
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    | 0inputs+0outputs (15major+16937minor)pagefaults 0swaps
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    | # time ./after/nft -jeaf large_ruleset.json >/dev/null
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    | 0.18user 0.44system 0:00.70elapsed 89%CPU (0avgtext+0avgdata 68484maxresident)k
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    | 0inputs+0outputs (15major+16645minor)pagefaults 0swaps
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    Bugzilla: https://bugzilla.netfilter.org/show_bug.cgi?id=1479
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    Reported-by: Derek Dai <daiderek@gmail.com>
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    Signed-off-by: Phil Sutter <phil@nwl.cc>
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---
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 src/parser_json.c | 28 ++++++++++++++++++----------
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 1 file changed, 18 insertions(+), 10 deletions(-)
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diff --git a/src/parser_json.c b/src/parser_json.c
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index ddc694f..107dc38 100644
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--- a/src/parser_json.c
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+++ b/src/parser_json.c
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@@ -3646,42 +3646,50 @@ static int json_verify_metainfo(struct json_ctx *ctx, json_t *root)
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 }
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 struct json_cmd_assoc {
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-	struct json_cmd_assoc *next;
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+	struct hlist_node hnode;
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 	const struct cmd *cmd;
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 	json_t *json;
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 };
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-static struct json_cmd_assoc *json_cmd_list = NULL;
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+#define CMD_ASSOC_HSIZE		512
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+static struct hlist_head json_cmd_assoc_hash[CMD_ASSOC_HSIZE];
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 static void json_cmd_assoc_free(void)
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 {
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 	struct json_cmd_assoc *cur;
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+	struct hlist_node *pos, *n;
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+	int i;
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-	while (json_cmd_list) {
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-		cur = json_cmd_list;
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-		json_cmd_list = cur->next;
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-		free(cur);
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+	for (i = 0; i < CMD_ASSOC_HSIZE; i++) {
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+		hlist_for_each_entry_safe(cur, pos, n,
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+					  &json_cmd_assoc_hash[i], hnode)
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+			free(cur);
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 	}
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 }
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 static void json_cmd_assoc_add(json_t *json, const struct cmd *cmd)
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 {
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 	struct json_cmd_assoc *new = xzalloc(sizeof *new);
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+	int key = cmd->seqnum % CMD_ASSOC_HSIZE;
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-	new->next	= json_cmd_list;
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 	new->json	= json;
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 	new->cmd	= cmd;
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-	json_cmd_list	= new;
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+
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+	hlist_add_head(&new->hnode, &json_cmd_assoc_hash[key]);
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 }
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 static json_t *seqnum_to_json(const uint32_t seqnum)
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 {
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-	const struct json_cmd_assoc *cur;
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+	int key = seqnum % CMD_ASSOC_HSIZE;
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+	struct json_cmd_assoc *cur;
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+	struct hlist_node *n;
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-	for (cur = json_cmd_list; cur; cur = cur->next) {
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+
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+	hlist_for_each_entry(cur, n, &json_cmd_assoc_hash[key], hnode) {
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 		if (cur->cmd->seqnum == seqnum)
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 			return cur->json;
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 	}
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+
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 	return NULL;
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 }
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-- 
bfbb76
2.31.1
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