From: erik quanstrom <quanstro@quanstro.net>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] kernel development: how not to
Date: Fri, 5 May 2006 10:41:57 -0500 [thread overview]
Message-ID: <00842b4663291b0523bb203740d23f74@quanstro.net> (raw)
sort of. it's an extension. here's the kerneltrap summary:
http://kerneltrap.org/node/6506
what linux actually said is that COW games (e.g. for freebsd's zero-copy
socket code) are worse than just copying the data.
the real difference between bsd's stuff and what linus did is
the linux trick is an explict system call, not a vm game.
but he misses that adding strange system calls that parallel
read and write is even bigger trouble. either your fundamental
object is a file (unix) or a block of memory (multix). pick a
lane! certainly don't mix the two at the same level.
linus may be right that the freebsd vm's techniques are broken.
i don't know.
the zero-copy idea is tantalizing. it would be neat to allow the
network stacks or devdraw to live in a user-level fileserver
without a performance (2 copy) penalty. but it may be the case
that allowing this trickery is more code than it is worth.
- erik
On Fri May 5 10:20:1CDT 2006, leimy2k@gmail.com wrote:
> Is the the vmslice that Linus told BSD people they were a bunch of
> retards for not having?
>
>
>
> On 5/5/06, erik quanstrom <quanstro@quanstro.net> wrote:
> > the linux guys decided to implement system calls
> > "splice" and "tee". splice concatinates the pages from
> > two files -- the vm equivalent of "cat a b". tee
> > is the vm equivalent of its namesake.
> >
> > http://lwn.net/Articles/181169/#Comments
> >
> > the best part is the conclusion -- "needs a bit more work".
> > ha!
> >
> > - erik
next reply other threads:[~2006-05-05 15:41 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-05 15:41 erik quanstrom [this message]
2006-05-08 15:44 ` Dave Lukes
-- strict thread matches above, loose matches on Subject: below --
2006-05-08 19:41 erik quanstrom
2006-05-05 15:12 erik quanstrom
2006-05-05 15:19 ` David Leimbach
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