Date: Thu, 08 May 2014 08:35:07 +0800 From: bycn82 <bycn82@gmail.com> To: Luigi Rizzo <rizzo@iet.unipi.it> Cc: "freebsd-ipfw@freebsd.org" <freebsd-ipfw@freebsd.org>, Freddie Cash <fjwcash@gmail.com> Subject: Re: feature of `packet per second` Message-ID: <536AD13B.6080907@gmail.com> In-Reply-To: <CA%2BhQ2%2BgXC9uNdtH1VCGa%2Bs1dPNWjErC9qfgXmEnfQ4SQ6Rnz_g@mail.gmail.com> References: <5360F1F4.9060808@gmail.com> <5361105C.1040203@freebsd.org> <53611738.8010103@gmail.com> <CAOjFWZ4zRUmcjG-r--OqoGEWcSZoWhtTykgAAHzCjoEWsMVS9g@mail.gmail.com> <53611EB1.4000406@gmail.com> <CA%2BhQ2%2BhjjS=AXVdnaEdFOKY1DqiLuX9iP0gy3wo6FbwnEdq_Qw@mail.gmail.com> <5364E097.9020106@gmail.com> <CA%2BhQ2%2BgXC9uNdtH1VCGa%2Bs1dPNWjErC9qfgXmEnfQ4SQ6Rnz_g@mail.gmail.com>
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On 5/4/14 1:19, Luigi Rizzo wrote:
>
>
>
> On Sat, May 3, 2014 at 2:27 PM, bycn82 <bycn82@gmail.com
> <mailto:bycn82@gmail.com>> wrote:
>
> On 5/2/14 16:59, Luigi Rizzo wrote:
>>
>>
>>
>> On Wed, Apr 30, 2014 at 6:02 PM, bycn82 <bycn82@gmail.com
>> <mailto:bycn82@gmail.com>> wrote:
>>
>>
>> fjwcash@gmail.com <mailto:fjwcash@gmail.com>
>> <mailto:fjwcash@gmail.com <mailto:fjwcash@gmail.com>>
>>
>> Thanks for your reply, and it is good to know the sysctl for
>> ICMP.
>>
>> finally it works.I just added a new `action` in firewall and
>> it is called `pps`, that means it can be generic purpose
>> while the net.inet.icmp.icmplim is only for ICMP traffic.
>>
>> the usage will be like below
>>
>> root@F10:/usr/src/sbin/ipfw # .*/ipfw add pps 1 icmp from any
>> to any*
>> 00100 pps 1 icmp from any to any
>> root@F10:/usr/src/sbin/ipfw # ./ipfw show
>> 00100 9 540 pps 1 icmp from any to any
>> 65535 13319 1958894 allow ip from any to any
>> root@F10:/usr/src/sbin/ipfw #
>>
>>
>> hi,
>> as julian said it would be great if you would like to share your code
>> so we can integrate it in future ipfw releases.
>> Once again citing Julian, dummynet is a bit of a superset of pps but
>> not exactly, so i see value in the additional feature.
>>
>> One thing to keep in mind in the implementation:
>>
>> the burst size used for limiting is an important parameter that
>> everyone forgets. 1 pps is basically "don't bother me".
>> 1000 pps could be "1000 packets every fixed 1-sec interval"
>> or "1 packet every ms" or (this is more difficult)
>> "20 pkt in the last 50ms interval".
>>
>> If i were to implement the feature i would add two parameters
>> (burst, I_max) with reasonable defaults and compute the internal
>> interval and max_count as follows
>> if (burst > max_pps * I_max)
>> burst = max_pps * I_max; // make sure it is not too large
>> else if (burst < max_pps / HZ)
>> burst = max_pps * HZ; // nor too small
>> max_count = max_pps / burst;
>> interval = HZ * burst / max_pps;
>> count = 0; // actual counter
>>
>> then add { max_count, interval, timestamp, count } to the rule
>> descriptor.
>> On incoming packets:
>>
>> if (ticks >= r->interval + r->timestamp) {
>> r->timestamp = r->ticks;
>> r->count = 1;
>> return ACCEPT;
>> }
>> if (r->count > r->max_count)
>> return DENY;
>> r->count++;
>> return ACCEPT;
>>
>> cheers
>> luigi
>>
> Hi Luigi,
> You are right, it will be more generic if provide two parameters
> as you described,
> But this PPS feature should not be used to control the traffic
> rate, the dummynet you provided is the correct way.
> So I am thinking in what kind of scenario, people need this PPS
> feature?
> in my opinion, people will use PPS only when they want to limit
> the connections/transactions numbers. ( already have limit command
> to limit the connections)
> So I think provide a simple PPS feature is good enough, and we can
> improve it if someone complaint on this.
>
>
> pps has a strong reason to exist because it is a lot cheaper
> than a dummynet pipe, and given its purpose is to police
> traffic (icmp, dns requests, etc) which should not even
> get close to the limit which is set, I think it is
> a completely reasonable feature to have.
>
> Given that the above code is the complete implementation
> with the two parameters (burst and interval) there is no
> reason not to use them, at least internally.
>
> Then you could choose not to expose them as part of the
> user interface (though since you are implementing a new
> option from scratch, it is completely trivial to
> parse 1, 2 or 3 arguments and set defaults for the others).
>
> cheers
> luigi
OK, PPS with 2 parameters , it is done,
But how to get the current time in millisecond?
any recommendation?
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