RE: QMC driver for 860?

RE: QMC driver for 860?

[Joakim Tjernlund]

> OK
>
> You asked for it ;).
>
> The file netvia_tsa.c is the actual QMC + stuff driver.
> The file netvia_bri.c is an example driver.
> The header files are the QMC definitions.
>
> Linux kernel version is 2.4.20.
>
> Don't hesitate to ask for any explanations.
>
> Pantelis

Thanks a lot!

I have just browsed the driver and I noticed that there is room for performance
improvements in netvia_tsa.c w.r.t memcpy(). You can avoid the memcpy() call
for received packets by using invalidate_dcache_range(). I did this for
the 8xx_io/enet.c driver a few weeks ago(it's not in BK yet).

See http://lists.linuxppc.org/linuxppc-embedded/200210/msg00317.html
and
http://lists.linuxppc.org/linuxppc-embedded/200210/msg00272.html

   Jocke


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Re: QMC driver for 860?

[Pantelis Antoniou]

Joakim Tjernlund wrote:

>>OK
>>
>>You asked for it ;).
>>
>>The file netvia_tsa.c is the actual QMC + stuff driver.
>>The file netvia_bri.c is an example driver.
>>The header files are the QMC definitions.
>>
>>Linux kernel version is 2.4.20.
>>
>>Don't hesitate to ask for any explanations.
>>
>>Pantelis
>>
>>
>
>Thanks a lot!
>
>I have just browsed the driver and I noticed that there is room for performance
>improvements in netvia_tsa.c w.r.t memcpy(). You can avoid the memcpy() call
>for received packets by using invalidate_dcache_range(). I did this for
>the 8xx_io/enet.c driver a few weeks ago(it's not in BK yet).
>
>See http://lists.linuxppc.org/linuxppc-embedded/200210/msg00317.html
>and
>http://lists.linuxppc.org/linuxppc-embedded/200210/msg00272.html
>
>   Jocke
>
>
>
>
>
Yes, I know the trick. I'm looking forward to see your changes
make it in. As it stands I'm not tracking the BK PPC tree, but
the Linus tree. Being behind the company firewall, BK is not
very useful.

In this driver case since I'm reading the packet in a non-cachable
area, and not directly in a skb, I'm not convinced that
the invalidate_dcache_range will be a great win.

If you do any performance testing I'm very interested in
your results.

Pantelis

P.S. Is there anyone in the list interested in this?
Should I clean it up, and submit it?


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Re: QMC driver for 860?

[Joakim Tjernlund]

>
> Joakim Tjernlund wrote:
>
> >>OK
> >>
> >>You asked for it ;).
> >>
> >>The file netvia_tsa.c is the actual QMC + stuff driver.
> >>The file netvia_bri.c is an example driver.
> >>The header files are the QMC definitions.
> >>
> >>Linux kernel version is 2.4.20.
> >>
> >>Don't hesitate to ask for any explanations.
> >>
> >>Pantelis
> >>
> >>
> >
> >Thanks a lot!
> >
> >I have just browsed the driver and I noticed that there is room for performance
> >improvements in netvia_tsa.c w.r.t memcpy(). You can avoid the memcpy() call
> >for received packets by using invalidate_dcache_range(). I did this for
> >the 8xx_io/enet.c driver a few weeks ago(it's not in BK yet).
> >
> >See http://lists.linuxppc.org/linuxppc-embedded/200210/msg00317.html
> >and
> >http://lists.linuxppc.org/linuxppc-embedded/200210/msg00272.html
> >
> >   Jocke
> >
> Yes, I know the trick. I'm looking forward to see your changes
> make it in. As it stands I'm not tracking the BK PPC tree, but
> the Linus tree. Being behind the company firewall, BK is not
> very useful.

The patch should apply to linus tree as well. There is just a small bug
in my second version(the invalidate_dcache_range() call must be moved).

>
> In this driver case since I'm reading the packet in a non-cachable
> area, and not directly in a skb, I'm not convinced that
> the invalidate_dcache_range will be a great win.

It should be a win since the patch removes the need for non-cachable memory and a
memcpy()(only add a invalidate_dcache_range call for non cache coherent CPUs like the 8xx).

 Jocke

>
> If you do any performance testing I'm very interested in
> your results.
>
> Pantelis
>
> P.S. Is there anyone in the list interested in this?
> Should I clean it up, and submit it?

Is QMC supported on other families than 8xx? If so I think it would be a good idea.
The 862 even has the QMC built in so there must be a need for this.


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Re: [linuxppc-embedded:] Re: QMC driver for 860?

[Reinhard Schwillinsky]

Pantelis Antoniou wrote:
> [...]
> P.S. Is there anyone in the list interested in this?
> Should I clean it up, and submit it?
>
Yes! I am interested in this!
rg Reinhard

--
----------------------------------------------------
Reinhard Schwillinsky        Tel.: ++43/1/205 255/210
Maxxio technologies GmbH     Fax.: ++43/1/205 255/900
Prinz Eugen Strasse 8        A-1040 Vienna/Austria


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Re: [linuxppc-embedded:] Re: QMC driver for 860?

[Pantelis Antoniou]

Reinhard Schwillinsky wrote:

>
> Pantelis Antoniou wrote:
>
>> [...]
>> P.S. Is there anyone in the list interested in this?
>> Should I clean it up, and submit it?
>>
> Yes! I am interested in this!
> rg Reinhard
>
> --
> ----------------------------------------------------
> Reinhard Schwillinsky        Tel.: ++43/1/205 255/210
> Maxxio technologies GmbH     Fax.: ++43/1/205 255/900
> Prinz Eugen Strasse 8        A-1040 Vienna/Austria
>
>
>
>
>
OK, since there is apparently great interest (of two persons)
I'll try and clean it up, so that only the relevant QMC bits remain.
I will also add the change suggested by Joakim.

In the meantime I'll try to find some hosting place for the
current code so that you can see it.

Keep in mind that a QMC driver by itself is not interesting.
It is some kind of a meta-driver, that needs another
'instantazation' driver to make it something useful.
I.e. it could be a simple read/write driver for connection
to a codec, or it could be a ISDN driver.

Anyway, please be patient.

Pantelis Antoniou
INTRACOM S.A.


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