I think i am happy now, please read again...
I have benchmarked parallel archiver using parallel LZMA using 5 threads on a quad core, so this have giving false results on the
So i have started parallel archiver with a single thread and this has giving a more accurate results, here is my correction please read again...
I have come to an interresting subject, so be smart and follow with me please...
I have tried to do a worst scalability prediction with an HDD hardisk
for my parallel archiver(you will find my parallel archiver here:
http://pages.videotron.com/aminer/) ; with Parallel LZMA, and i think it's worst than what i have thought..
there is four things in my Parallel LZMA algorithm:
First we have to copy serially a stream from the hardisk to the memory and this will take in average 0.2 second and in the compression method we have to copy a stream to the memory and this will take in average 0.05 second and in the compression method you have to compress a stream to another stream in memory and this will take in average 13 seconds seconds and in the compression method you have to copy a compressed stream to a hardisk file and this will take in average 0.01 second.
So we have the serial part that is: 0.2 second + 0.01 second + 0.05 second = 0.26 second = 0.02%
and the parallel part will that is: 13 seconds = 0.98%
So the worst case scalability scenario using an HDD and using the Amdahl equation will
give us: 1/0.02% + (0.98%/N) = 50X scalability (N: is the number of cores)
So this will scale up to: 50X , so as you have noticed with an HDD hardisk this is a good scalability.
So what can we do to scale more parallel archiver using parallel LZMA ?
You can for example use a RAID 10 with a base configuration of 4 HDD hardrives,so this will cut in 4 the 0.2 second and the 0.01 second , so this will give a scalability of 124X and this is better.. but to speed more the things we can use SSD hardrives that are 2X time faster than a HDD hardrives and with a RAID 10 configuration and this will give: 434X worst case scalability.
So as you have noticed if you are using only an HDD with a multicore system you will get a 50X scalability with my
parallel archiver using parallel LZMA, and if you use RAID 10 with SSD drives you will get 434X scalability.
And this is why i have talked about RAID 10 etc.
Amine Moulay Ramdane.