Instruction time (lwi) on Microblaze

[dlaur]

Hi,

I'm trying to accomodate with microblaze on a spartan starter kit 3a boar
and now I'm looking into measuring execution time of different things.
have a small loop that I'm analysing:

while(1)
{
if (intr_served==1) // this is set by an interrupt handler triggered by
FIT timer running at 1 second
{
intr_served=0;
num=0; //resets the global counter
}
num++;
}

Microblaze is running at 62500000 with the following specs:

BEGIN microblaze
PARAMETER INSTANCE = microblaze_0
PARAMETER C_AREA_OPTIMIZED = 0
PARAMETER C_USE_BARREL = 1
PARAMETER C_DEBUG_ENABLED = 0
PARAMETER HW_VER = 8.40.b
PARAMETER C_USE_ICACHE = 0
PARAMETER C_CACHE_BYTE_SIZE = 2048
PARAMETER C_USE_DCACHE = 0
PARAMETER C_DCACHE_BYTE_SIZE = 2048
PARAMETER C_NUMBER_OF_PC_BRK = 1
PARAMETER C_NUMBER_OF_RD_ADDR_BRK = 0
PARAMETER C_NUMBER_OF_WR_ADDR_BRK = 0
BUS_INTERFACE DPLB = mb_plb
BUS_INTERFACE IPLB = mb_plb
BUS_INTERFACE DLMB = dlmb
BUS_INTERFACE ILMB = ilmb
PORT INTERRUPT = microblaze_0_interrupt
PORT Trace_PC = microblaze_0_Trace_PC_to_chipscope_ila_0
PORT Trace_Valid_Instr
microblaze_0_Trace_Valid_Instr_to_chipscope_ila_0
PORT Trace_Data_Read = microblaze_0_Trace_Data_Read_to_chipscope_ila_0
PORT Trace_Data_Write = microblaze_0_Trace_Data_Write_to_chipscope_ila_0
PORT Trace_Data_Address
microblaze_0_Trace_Data_Address_to_chipscope_ila_0
PORT Trace_Reg_Addr = microblaze_0_Trace_Reg_Addr_to_chipscope_ila_0
PORT Trace_Reg_Write = microblaze_0_Trace_Reg_Write_to_chipscope_ila_0
PORT Trace_OF_PipeRun = microblaze_0_Trace_OF_PipeRun_to_chipscope_ila_0
PORT Trace_MEM_PipeRun
microblaze_0_Trace_MEM_PipeRun_to_chipscope_ila_0
PORT Trace_EX_PipeRun = microblaze_0_Trace_EX_PipeRun_to_chipscope_ila_0
PORT Trace_MB_Halted = microblaze_0_Trace_MB_Halted_to_chipscope_ila_0
END

I don't have any DDR memory. The code runs from BRAM.

When i check out the code with chipscope to see how many clock cycles m
loop takes, I notice that the lwi instruction takes more than 1 cycle, a
written in the manual. Any ideas why this happens ?

Any ideas will be greatly appreciated

Thanks !



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