Re: [microblaze-uclinux] FSL Driver Overhead

[Aurash <aurelian.lazarut@xxxxxxxxxxx>]

Hi Ivan,
nice paper, thanks for sharing this information with us
I have a question about the methodology of taking speed mesurements.
your are saying that data was copied over a channel, did you mesure the 
capabilities of the channel without any encryption? what is a litttle 
bit odd is that the ratio is not constant, and is very much dependant on 
the file size, it looks like is getting flat after a certain file size 
(I'm guessing here) and this can be due to bandwidth limitation.
did you try with files from the RAMDISK to minimise the channel overhead 
? (assuming that you took measurements by sourcing data from the network)

Aurash

Ivan wrote:

> Hi Jonathan,
>
> I did something similar for my PhD. Thesis. In my work the main
> objective was not to measure the performance but I obtained some
> results. I attach to this mail a recently published paper with my work.
> I think that the results are interesting for you. The coprocessors have
> been implemented using one master FSL bus for receiving the encryption
> key and the decryption key (SSH2 uses different keys for each
> operation), and two pairs of master/slave FSL buses to send/receive
> data.
>
> Regards,
>
> Ivan
>
> El lun, 02-01-2006 a las 23:15 -0800, Jonathan Jung escribió:
>  
>
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > 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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> >    


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