From owner-freebsd-net  Thu Mar  7  4: 0:38 2002
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Date: Thu, 7 Mar 2002 03:51:41 -0800 (PST)
From: Julian Elischer <julian@elischer.org>
To: Bill Fumerola <billf@mu.org>
Cc: Terry Lambert <tlambert2@mindspring.com>, net@freebsd.org,
	hackers@freebsd.org
Subject: Re: in_pcblookup_hash() called multiple times
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what  would be even nicer is if ipfw found the cached entry and passed it
back to ip_input so it didn't need to :-)

On Thu, 7 Mar 2002, Bill Fumerola wrote:

> On Wed, Mar 06, 2002 at 05:07:55PM -0800, Terry Lambert wrote:
> 
> > There are redundant calls to the in_pcblookup_hash() in the
> > ip_fw_chk() function called via (*ip_fw_chk_ptr)() in the
> > ip_input path.
> 
> in addition to what you're talking about, ipfw will repeat the hash
> lookup for every rule it goes through that has a uid or gid keyword.
> 
> http://people.freebsd.org/~billf/bsdcon2000/presentation/graphics/countudpfromanytoanyuidbillf.png
> http://people.freebsd.org/~billf/bsdcon2000/presentation/graphics/counttcpfromanytoanyuidbillf.png
> 
> 'old ipfw' = ipfw as of oct 2000
> 'new ipfw' = ipfw w/pcb cache + uid cache (as part of a compiled ruleset)
> 
> in the compiled case, in_pcblookup_hash() is called the first time a uid
> needs compared. after that, uid lookups become a integer compare and not
> another call to in_pcblookup_hash(). gid lookups still use groupmember()
> each rule, but also don't have to do a pcb lookup each time.
> 
> > Right now, I'm just talking about a way ip_input could pass
> > the already looked up input inpcb to tcp_input, udp_input,
> > or udp_ctlinput -- all of which repeat the lookup operation.
> 
> my results are with a cached lookup just in the ipfw code, but if
> ip_input() did the lookup and passed it to both ipfw and the protocol
> handler that would be nice.
> 
> -- 
> - bill fumerola / fumerola@yahoo-inc.com / billf@FreeBSD.org / billf@mu.org
> 
> 
> 
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