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Trafic Srio Throughput!!

NOURA
Prodigy 75 points

Hello everyone,

I'm testing Srio performance using two differents scenarios on dsp C6678.

In the first case i have 2LSUs that shared the same port and send data throught  switch "sps1848" to 2 different destinations (ID1,ID2), the sending is on 2X and reception in 1X for each destination .

In the second case i have 1LSU that send data throught switch to 2 different destinations (ID1,ID2) , the sending is on 2x and reception on 1x for each destination .

I can't find an explanation for the result as presented in figure as follow:

Thanks.

Noura.

  • 0
    TI__Mastermind 28085 points
    Hi,

    It is a expected results. If you sending data to one destination (2X=>2X) with 1LSU means you can got the better throughput. If you using two destination(2X=>1x,1x) means better to use 2LSU.

    If you configured 1LSU(Load Store Unit) for transmission means the data is going out to the same LSU. Lower byte count it should be ok, but higher byte count LSU transfer is over loaded (LSU is busy).

    Each LSU is a set of shadow registers. Each shadow register can be programmed for setting up a transaction ahead of time. When the LSU is free, the data is transferred from the shadow register to the LSU register. The point at which the data is actually transferred from the shadow registers to the actual LSU registers, the values of LSU0-5 registers can be read. Prior to that, a read of these registers will indicate the last value that was present in these registers. This implies that the new values cannot be read until a write to REG5 and further constrained by the fact that there is no other command ahead of the current command being setup. Reg6 can be read as and when it is written to, as it is used for locking and releasing.

    The total shadow registers that can be assigned to each LSU is configurable, for a total of 32 sets of registers. Of the total of 32 shadow register, 16 of them are used for LSU0-3, while the other 16 can only be used for LSU4-7. The total shadow registers assigned to an LSU is setup via the RIO_LSU_SETUP_REG0.

    In your second test case you have configured 1LSU(Load Store Unit) for transmission. If the LSU is free, The shadow register is now ready to be used by the LSU. If the LSU is already busy, the data will be simply held in the shadow register. When the LSU finishes with the transaction, the shadow register is ready to be used by the LSU. So that only you got throughput drop in your second test case.

    Thanks,