Marko Ristola a écrit :
Hi.
I have written some Mantis bandwidth related
DMA transfer optimizations on June/July this year.
They are now waiting for approval by Manu Abraham.
Those reduce CPU pressure, increasing the bandwidth
that can be received from the DVB card. 45MS/s bandwidth
support will surely benefit from those patches.
Main features:
1. Do one CPU interrupt per 16KB data instead per 4KB data.
My implementation benefits only Mantis cards.
https://patchwork.kernel.org/patch/107036/
2. Remove unnecessary big CPU overhead, when data is delivered
from the DVB card's DMA buffer into Linux kernel's DVB subsystem.
Number 2 reduces the CPU pressure by almost 50%.
This implementation benefits many other Linux supported DVB cards too.
http://patchwork.kernel.org/patch/108274/
Those helped with my older single CPU Core computer with 256-QAM,
delivering HDTV channel into the network and watching the
HDTV channel with a faster computer.
The performance bottlenecks could be seen on the
command line with "perf top".
I had to increase PCI bus latency setting into 64 too from the BIOS.
Moving DVB device into separate IRQ line with Ethernet card helped too,
because Ethernet card did an interrupt per ethernet packet.
So if the hardware can deliver 45MS/s data fast enough, software side
can be optimized up
to some point. My patches contain the most easy major optimizations
that I found.
If you can test some of those patches, it might help to get them into
Linux kernel
faster.
Best regards,
Marko Ristola
OK these optimizations look like a step into the good direction. I guess
what is also missing is a tuner which can handle that in DVB-S2, which
does not seem obvious. The mantis card can do that?
Thx
Bye
Manu
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