Re: [microblaze-uclinux] FSL Driver Overhead

[Paul Hartke <phartke@xxxxxxxxxxxx>]

Sounds like a cool project.  Are you using the opensll engine interface to
interface with your module?  Have you run standalone synthetic benchmarks
to determine the amount of speedup to expect?  4 FSL writes and 8 FSL reads
for every 64 bits of data to be encrypted isn't so efficient.

Paul

Quoting Jonathan Jung <jwjung@xxxxxxxxxxxxx>:
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> Hi List,
>
> I've had good success implementing a hardware accelerated version of
> Openssl on my Virtex II Pro FPGA via uClinux.  However, I'm
> wondering  if anybody has experience with the amount of overhead
> involved FSL reading/writing.
>
> For example, encrypting a 700KB file in software takes (using AES):
>
> real 2m 9.96s
> user 1m 33.98s
> sys 0m 33.29s (file read/writes)
>
> Encrypting the same 700 KB file with software/hardware takes:
>
> real 3m 23.51s
> user 0m 10.40s
> sys 1m 56.57s (file read/writes, FSL read/write)
>
> As you can see, software version consumes 1m 33 s of CPU time running
> the openssl code.  The hardware/software combo takes only 10 seconds
> of time executing the openssl code, but requires 1 minute and 56
> seconds of overhead in unrelated system calls, I'm sure is because of
> the reading and writing to the FSL.
>
> Each 64 bits of data encrypted requires 4 FSL writes, and 8 FSL
> Reads.  The initial one time setup requires 60 FSL writes.
>
> The hardware is quite fast, running at 100 Mhz, and requires only
> about 30 cycles to process the data.
>
> The profiler in uClib isn't active anymore, so I can't use that to do
> a line by line check for the time it takes for each write, but a best
> estimate is it takes almost a minute and half to do all those reads
> and writes.  Am I doing something funny, or is that just the amount
> of overhead required?  I'm only doing the initial drive init once
> throughout the whole process.  The FSL driver doesn't look like it's
> doing too many crazy things to write to the FSL, so I wouldn't think
> that would be the time consumer.
>
> Any FSL related performance comments are welcome!
>
> Thanks again to John for the excellent driver.
>
> Jonathan
>
>
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