Re: [PATCH] acl: fix trie splitting

[Konstantin Ananyev <konstantin.v.ananyev@yandex.ru>]

It is not really clear to me what is the actual problem
and what are you trying to fix here...


> When using a large number of ACL rules, the trie is supposed to split when there are over 2048 nodes.

What do you mean by 'there'?
As I remember, it decided to split set of rules, when trie starts to 
grow too fast: if merging of last rule creates more then cur_node_max 
new nodes, then it splits.

> However, node_count is negative, so node_count > context->cur_node_max never actually runs, so all the nodes created from the rules end up being in one trie.

Hmm... sentence that node count is negative is too cryptic for me.
Obviously there are plenty examples with rule-sets that causes more then
one trie to be created. Simplest way to check that, just run acl autotest:
echo 'acl_autotest' | 
./x86_64-default-linuxapp-gcc-dbg/app/test/dpdk-test --lcores=15 
--no-pci --no-huge --log-level=acl,debug
...
You will see that there are bunch of cases with more then one trie.
Another way - try with dts test-cases for acl. few of them will create
multiple tries:
git clone -v http://dpdk.org/git/tools/dts/
cd dts
gzip -cd dep/test-acl-input.tar.gz | tar xfv -
./x86_64-default-linuxapp-gcc-dbg/app/dpdk-test-acl --lcores=15 --no-pci \
--no-huge --log-level=acl,debug -- \
--rulesf=/home/kananyev/devel/dts/test-acl-input/acl2v4_10k_rule \
--tracef=/home/kananyev/devel/dts/test-acl-input/acl2v4_10k_trace \
--verbose=0
...
dump_config:
rulesf:/home/kananyev/devel/dts/test-acl-input/acl2v4_10k_rule
tracef:/home/kananyev/devel/dts/test-acl-input/acl2v4_10k_trace
rulenum:65536
tracenum:65536
tracestep:256
bldcat:3
runcat:1
maxsize:0
iter:1
verbose:0
alg:0(default)
ipv6:0
ACL: Gen phase for ACL "TESTACL":
runtime memory footprint on socket -1:
single nodes/bytes used: 54437/435496
quad nodes/vectors/bytes used: 55775/189941/1519528
DFA nodes/group64/bytes used: 9516/28940/14819336
match nodes/bytes used: 9760/1249280
total: 18027888 bytes
max limit: 18446744073709551615 bytes
ACL: Build phase for ACL "TESTACL":
node limit for tree split: 2048
nodes created: 129488
memory consumed: 184549530
ACL: trie 0: number of rules: 655, indexes: 4
ACL: trie 1: number of rules: 9129, indexes: 4
rte_acl_build(3) finished with 0
acl context <TESTACL>@0x103adfa80
   socket_id=-1
   alg=3
   first_load_sz=4
   max_rules=65536
   rule_size=96
   num_rules=9784
   num_categories=3
   num_tries=2


> 
> Original PR with sample files and test output can be found here:
> https://github.com/DPDK/dpdk/pull/50
> 
> Fixes: dc276b5780c2 ("acl: new library")
> Signed-off-by: Arthur Leung <arcyleung@gmail.com>
> ---
>   app/test-acl/test-acl.sh | 2 +-
>   lib/acl/acl_bld.c        | 9 +++------
>   2 files changed, 4 insertions(+), 7 deletions(-)
> 
> diff --git a/app/test-acl/test-acl.sh b/app/test-acl/test-acl.sh
> index 30814f3fe2..59bfa121cf 100644
> --- a/app/test-acl/test-acl.sh
> +++ b/app/test-acl/test-acl.sh
> @@ -17,7 +17,7 @@
>   # <proto>'/'<mask>
>   # trace record format:
>   # <src_ip_addr><space><dst_ip_addr><space> \
> -# <src_port><space<dst_port><space><proto>...<rule_id>
> +# <src_port><space><dst_port><space><proto>...<rule_id>
>   #
>   # As an example:
>   # /bin/bash app/test-acl/test-acl.sh build/app/dpdk-test-acl \
> diff --git a/lib/acl/acl_bld.c b/lib/acl/acl_bld.c
> index 2816632803..6064a8103b 100644
> --- a/lib/acl/acl_bld.c
> +++ b/lib/acl/acl_bld.c
> @@ -946,7 +946,7 @@ build_trie(struct acl_build_context *context, struct rte_acl_build_rule *head,
>   	struct rte_acl_build_rule **last, uint32_t *count)
>   {
>   	uint32_t n, m;
> -	int field_index, node_count;
> +	int field_index;
>   	struct rte_acl_node *trie;
>   	struct rte_acl_build_rule *prev, *rule;
>   	struct rte_acl_node *end, *merge, *root, *end_prev;
> @@ -1048,15 +1048,13 @@ build_trie(struct acl_build_context *context, struct rte_acl_build_rule *head,
>   			}
>   		}
>   
> -		node_count = context->num_nodes;
>   		(*count)++;
>   
>   		/* merge this rule into the trie */
>   		if (acl_merge_trie(context, trie, root, 0, NULL))
>   			return NULL;
>   
> -		node_count = context->num_nodes - node_count;
> -		if (node_count > context->cur_node_max) {
> +		if (context->num_nodes > (context->cur_node_max * context->num_tries)) {
>   			*last = prev;
>   			return trie;
>   		}
> @@ -1368,6 +1366,7 @@ acl_build_tries(struct acl_build_context *context,
>   	for (n = 0;; n = num_tries) {
>   
>   		num_tries = n + 1;
> +		context->num_tries = num_tries;
>   
>   		last = build_one_trie(context, rule_sets, n, context->node_max);
>   		if (context->bld_tries[n].trie == NULL) {
> @@ -1411,8 +1410,6 @@ acl_build_tries(struct acl_build_context *context,
>   		}
>   
>   	}
> -
> -	context->num_tries = num_tries;
>   	return 0;
>   }
>