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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