Juan Manuel Placco
|
Re: QNX 6.4 - QNX 6.3 FS Comparison
|
Juan Manuel Placco
11/23/2008 12:19 PM
post17142
|
Re: QNX 6.4 - QNX 6.3 FS Comparison
David, thank you very much for the response!
In a general way, I supposed that it was going to exist such performance difference on 79 vs 179 partition types because
of the implementation on the copy-on-write as you mention, after reading the wiki introduction. Mostly in my 'byte per
byte' throughput test.
(>> WIKI: The first reason is that most people do not write a single byte at a time to a block device)
Other thing: you have mentioned:
>> The new QNX6 filesystem must do additional writing, to implement the copy-on-write This can result in slightly lower
write throughput as compared to the QNX4 filesystem.
According to my workbench's numbers in the 'file descriptor' method, the performance was decremented in aprox 73% in
both cases (dev1 and dev2), which I found too much.
It would be very interesting for me to know why this huge difference (in 'fd' method) in both OS. It's only about the FS
implementation? Or the procnto is implied? Since I call 'open' once at the beggining, not in every write or read. I
will be very thankful if you can help me to clarify these.
The differences in FILE* testing method were more reasonable (15% slower in DEV2), and even faster (1%) in DEV1 node (2
CPU with 1 GB RAM)
But what worries a little to me is how it will be the performance difference working with a data base (MySQL for
example) in hard, real time conditions and how can I deal with that (using the power-safe qnx6 filesystem, of course)
Thank you very much again!
Regards,
Juan Manuel
|
|
|