Re: [nft PATCH] json: echo: Speedup seqnum_to_json()

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Mon, Nov 30, 2020 at 09:43:04PM +0100, Jose M. Guisado wrote:
> On 23/11/20 0:56, Phil Sutter wrote:
> > Hi,
> > 
> > On Sat, Nov 21, 2020 at 01:17:24PM +0100, Pablo Neira Ayuso wrote:
> > > On Fri, Nov 20, 2020 at 08:16:40PM +0100, Phil Sutter wrote:
> > > > Derek Dai reports:
> > > > "If there are a lot of command in JSON node, seqnum_to_json() will slow
> > > > down application (eg: firewalld) dramatically since it iterate whole
> > > > command list every time."
> > > > 
> > > > He sent a patch implementing a lookup table, but we can do better: Speed
> > > > this up by introducing a hash table to store the struct json_cmd_assoc
> > > > objects in, taking their netlink sequence number as key.
> > > > 
> > > > Quickly tested restoring a ruleset containing about 19k rules:
> > > > 
> > > > | # time ./before/nft -jeaf large_ruleset.json >/dev/null
> > > > | 4.85user 0.47system 0:05.48elapsed 97%CPU (0avgtext+0avgdata 69732maxresident)k
> > > > | 0inputs+0outputs (15major+16937minor)pagefaults 0swaps
> > > > 
> > > > | # time ./after/nft -jeaf large_ruleset.json >/dev/null
> > > > | 0.18user 0.44system 0:00.70elapsed 89%CPU (0avgtext+0avgdata 68484maxresident)k
> > > > | 0inputs+0outputs (15major+16645minor)pagefaults 0swaps
> > > 
> > > LGTM.
> > > 
> > > BTW, Jose (he's on Cc) should rewrite his patch to exercise the
> > > monitor path when --echo and --json are combined _and_ input is _not_
> > > json.
> 
> IIRC v4 of the patch already takes into account this situation. Specifically
> this piece of code inside netlink_echo_callback. Returning the
> json_events_cb (the path leading to the seqnum_to_json call) when input is
> json.

OK, I have pushed out this patch. Thanks for clarifying.