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Date:      Mon, 4 Dec 2000 21:44:38 -0700
From:      "Kenneth D. Merry" <ken@kdm.org>
To:        Bosko Milekic <bmilekic@technokratis.com>
Cc:        arch@FreeBSD.ORG
Subject:   Re: zero copy code review
Message-ID:  <20001204214438.A42689@panzer.kdm.org>
In-Reply-To: <Pine.BSF.4.21.0012021237540.91517-100000@jehovah.technokratis.com>; from bmilekic@technokratis.com on Sat, Dec 02, 2000 at 01:00:22PM -0500
References:  <20001201002235.D10772@panzer.kdm.org> <Pine.BSF.4.21.0012021237540.91517-100000@jehovah.technokratis.com>

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[ catching up with mail from this weekend ]

On Sat, Dec 02, 2000 at 13:00:22 -0500, Bosko Milekic wrote:
> 
> On Fri, 1 Dec 2000, Kenneth D. Merry wrote:
> 
> > It does have spls in the right places, in this case splimp() and splvm().
> > Would you just convert those to the proper mutexes, or are we going to go
> > with per-data-structure mutexes (i.e. a little finer granularity), or...?
> > (I don't know much about the mutex strategy we're using...)
> 
> 	For now, you won't be able to do anything with the splvm() stuff, as
>   the VM code has not yet been ripped out from under Giant (and likely
>   won't be for a while).
>   	A few notes Re: spl()s and mutexes in uipc_jumbo.c, in particular
>   (since that's where I would begin putting in mutexes):
> 
>   - Your jumbo_kmap singly linked list should probably not be manipulated
>     under splvm() [in fact, I think it's wrong]. The list should be
>     protected by a lock.

Okay.

>   - jumbo_freem should just be called jumbo_free, if the naming convention
>     is being adopted from the mbuf system (which it looks like it is). The
>     reason is that for mbufs, m_free() frees a single mbuf while m_freem()
>     frees an entire chain of them.

Okay.

>   - jumbo_pg_free should be ripped out from under splimp(); leave the
>     explicit splvm() in there, but protect the list manipulations with the
>     lock.

Okay.

> 	If most of the things pointed out earlier are fixed, and as long as
>   the code is not flawed (which I really doubt it would be anyway), I have
>   no objections to it going in soon and then attacking the above issue a
>   little later (If nobody gets to it within the next two weeks, I'll be
>   glad to do it myself once those 2 weeks are past).

Sounds good.  There have been other problems pointed out that we'll need to
fix as well before the code can go in.

Ken
-- 
Kenneth Merry
ken@kdm.org


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