Date: Wed, 2 Jun 2004 06:51:55 -0700 From: "Christian S.J. Peron" <csjp@freebsd.org> To: Andre Oppermann <andre@freebsd.org> Cc: ipfw@freebsd.org Subject: Re: ipfw cached ucred patch Message-ID: <20040602135155.GA31642@freefall.freebsd.org> In-Reply-To: <40BD9D3F.7090100@freebsd.org> References: <20040602043537.GA42327@freefall.freebsd.org> <40BD9D3F.7090100@freebsd.org>
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On 2 Jun 2004 Andre Oppermann wrote: > Christian S.J. Peron wrote: > >All, > > > >Currently, when you have any rules which contain UID/GID > >constraints, ipfw will lock the pcb hash and do a lookup > >to find the pcb associated with that packet -- > >One for each constraint. > > > >I have written a patch in attempt to minimize the impact > >of PCB related lookups for these type of firewall rules. > > > >This patch will have the following effects on firewalls which > >contain UID/GID constraints: > > > > o Greatly reduce the locking contention associated > > with PCB lookups. > > > > o Increase the performance of firewall in general by making > > PCB lookups O(1) rather than O(n) (where n represents > > number of UID/GID constraints in the ruleset) > > > >It would be greatly appriciated if people who are running ipfw > >rules sets containing UID/GID constraints tested this patch > >and reported any success or failures. > > > >The patch can be downloaded from: > > > >http://people.freebsd.org/~csjp/ip_fw2_cached_ucred.patch > > You can optimize it even further by directly copying the uid/gid > from the ucred while you hold the INP_LOCK. There is no need to > hold on to the entire ucred. It should be sufficient to do the > ucred lookup only once per packet in the ipfw code. If you don't > find an INPCB for the packet you'll do a negative lookup for every > uid/gid rule. I thought about this to, however in order to implement GID contraints properly, we need to use groupmember(9) which requires the entire cr_groups[16] located in the ucred. I thought it was more elegant and cheaper to avoid the memcpy(sizeof(gid_t) * NGROUPS) and stick with the mutex. Anyone else have other ideas? -- Christian S.J. Peron csjp@FreeBSD.ORG FreeBSD Committer
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