iptables-restore vs iptables-restore --noflush performance

iptables-restore vs iptables-restore --noflush performance

[Joubert Berger]

Anyone know why I would get a big performance difference between
"iptables-restore" and "iptables-restore --noflush"?

I have 6600 rules.  If I load with iptables-restore, it takes about 30sec.
If I use noflush, that turns in 1 min and 20+ seconds.

--joubert

Re: iptables-restore vs iptables-restore --noflush performance

[Steven M Campbell]

Joubert Berger wrote:
>Anyone know why I would get a big performance difference between
>"iptables-restore" and "iptables-restore --noflush"?
>
>I have 6600 rules.  If I load with iptables-restore, it takes about 30sec.
>If I use noflush, that turns in 1 min and 20+ seconds.
>
>--joubert
>
>  
Because you have 6600 rules and when you use no-flush you are adding 
another 6600?  If you do it several
times in a row I'll bet the time keeps getting worse.

The insert time for each rule is, among other things, dependent on the 
number of rules that
must be searched/manipulated, thus an explanation for the times you see.

You should only use --noflush if you really intend to add rules to the 
current  rule set rather
than replace them all.  What are you trying to accomplish here?

Re: iptables-restore vs iptables-restore --noflush performance

[Joubert Berger]

Actually, what I do is load the first time the 6600 rules.  The next
time I load the 6600 rules, I load them using different chains.  At
the end, I just change FORWARD to point to the newly created chains
and then delete the old chains.

Are you saying, if I have 6600 rules loaded, no matter what chain I
add the next 6600 rules (i.e. totaly new chain), performance is going
to go up?  In other words, performance (inserting of rules) is tied to
# of total rules and not # of rules added to a chain?

TIA

--joubert


On 7/25/05, Steven M Campbell <Netfilter@scampbell.net> wrote:
> Joubert Berger wrote:
> >Anyone know why I would get a big performance difference between
> >"iptables-restore" and "iptables-restore --noflush"?
> >
> >I have 6600 rules.  If I load with iptables-restore, it takes about 30sec.
> >If I use noflush, that turns in 1 min and 20+ seconds.
> >
> >--joubert
> >
> >
> Because you have 6600 rules and when you use no-flush you are adding
> another 6600?  If you do it several
> times in a row I'll bet the time keeps getting worse.
> 
> The insert time for each rule is, among other things, dependent on the
> number of rules that
> must be searched/manipulated, thus an explanation for the times you see.
> 
> You should only use --noflush if you really intend to add rules to the
> current  rule set rather
> than replace them all.  What are you trying to accomplish here?
> 
> 
> 
>