anyone understand torvald's critique of freebsd?

Ted Mittelstaedt tedm at
Mon Apr 24 10:19:37 UTC 2006

>-----Original Message-----
>From: Chuck Swiger [mailto:cswiger at]
>Sent: Saturday, April 22, 2006 7:51 PM
>To: Ted Mittelstaedt
>Cc: freebsd-questions
>Subject: Re: anyone understand torvald's critique of freebsd?
>Ted Mittelstaedt wrote:
>> Then why does Linus think manipulating the VM page table mappings
>> is bad?  That is, why does he -really- think it's bad, not the
>> publically-given reason?  Is it because Linux is extrordinairly
>> inefficient in page table mappings due to some structural decision
>> that Linus made that cannot be reversed now, that it could never
>> be any good at it?  Or is there some other reason?
>I can't speak with certainty as to what someone else might 
>think; no doubt Linus 
>is entirely capable of explaining his own position should you 
>wish to inquire, 

The guy is bitching about an option that's not even turned on,
thus it's not a legitimate criticism - there's an ulterior motive
somewhere.  He isn't going to explain this of course - if he was
being honest he never would have bitched about it in the first place.

>however....  :-)
>I think Linus doesn't care much for Zero-copy sockets because 
>for the common 
>case of 1500/1504-byte MTU, you end up wasting at least 60% of 
>a 4096-byte page 
>for each packet, and maybe ?three? times that much if your 
>hardware splits the 
>packet into separate pages for the mbuf header, the packet 
>headers, and the 
>packet data.

ram is cheap these days.

I've seen things before that are a lot faster to do the memory-hogging
way.  If this is one of these then the ram usage shouldn't be an


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