JagChris, on Fri Feb 2, 2007 11:33 PM, said:
Example: If you were blitting in 4 4k modules into the gpu every frame, thats 1,200,000 cycles a second wasted waiting for the blitter to load code in the local RAM.
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What is needed to program for the Jaguar
Started by TAdams, Nov 28 2005 7:56 AM
30 replies to this topic
#26 OFFLINE
Orion_
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Posted Mon Feb 5, 2007 9:34 AM
oh, by the way, real coders won't wait for the blitter, so, no cycles wasted.
#27 OFFLINE
JagChris
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Posted Mon Feb 5, 2007 11:48 AM
Orion_, on Mon Feb 5, 2007 7:34 AM, said:
JagChris, on Fri Feb 2, 2007 11:33 PM, said:
Example: If you were blitting in 4 4k modules into the gpu every frame, thats 1,200,000 cycles a second wasted waiting for the blitter to load code in the local RAM.
Good for you boss! Glad you got it all figured out.
#28 OFFLINE
JagChris
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Posted Mon Feb 5, 2007 12:04 PM
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But you're saying that a compiler his better than human mind...
Absolutely not. Nothing can beat hand written code for optimization or flexibility.
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No, i've never told that. There is a lot of good C coders, i talk with some everyday, i'm too bad in C, but how many of them think the ASM give faster, better result and smaller program than C.
What I meant was, every C coder that decides to code on the Jag probably will not be a lousy coder.
It would probably be best to use C for non time critical stuff and do the time critical stuff with assembly. It doesn't have to be completely one or the other.
It just means that the option to use C is more plausible now. No one is forced to use C on the Jag. They have a choice. Don't we all like choices?
#29 OFFLINE
Gorf
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Posted Mon Sep 17, 2007 11:02 AM
I know this thread has been dormant but the hits you take out in main are extremely insignificant
compared to running the 68k at all! And it definitely better than flipping code in and out.
the only time you run slower out in main is a DRAM page hit or refresh occurs and the indexed
load/store instructions can take up to five cycles to complete. It's probably taking a mip or two away
even in worst case senerios.
Oh and you need to interleave code to reach 80% efficiency. 18 MIPs is about all she wrote.
Fuggin cheapo fake dual port write backs.
compared to running the 68k at all! And it definitely better than flipping code in and out.
the only time you run slower out in main is a DRAM page hit or refresh occurs and the indexed
load/store instructions can take up to five cycles to complete. It's probably taking a mip or two away
even in worst case senerios.
Oh and you need to interleave code to reach 80% efficiency. 18 MIPs is about all she wrote.
Fuggin cheapo fake dual port write backs.
#30 OFFLINE
JagChris
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Posted Wed Jan 30, 2008 11:26 PM
'MORE THAN GAMES' link updated.
#31 OFFLINE
Gorf
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Posted Sun Mar 2, 2008 5:33 AM
Orion_, on Mon Feb 5, 2007 10:34 AM, said:
JagChris, on Fri Feb 2, 2007 11:33 PM, said:
Example: If you were blitting in 4 4k modules into the gpu every frame, thats 1,200,000 cycles a second wasted waiting for the blitter to load code in the local RAM.
A good coder should never make a processor sit around and wait, especially if it has interrupts
and can be doing something else. this is also a BIG reason why a lot of the games on the Jag suck.
The waste a lot of time waiting. Lazy coding is what that is.
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