Randy,
I have a Redhat 9 Linux machine with a 1.8 Ghz P4 that I could run your tests.
Eddie Dimond
Daniel Casey wrote:
Randy
I have a Linux box that I should be able to run your program on if you want to send it to me.
Daniel
Randolph Kahle wrote:
I have been investigating the performance of Java IO on different operating systems. The results are so different that I am concerned I am making some sort of fundamental mistake in my test.
I would appreciate help in determining if my results are correct.
The test is simple. I am creating a rather large file using stream IO and random access IO by writing a 4k buffer in a loop.
On my Mac OS X box (G4 1Ghz, 4200 RPM disk) I get
Block Size [4096] Loop Size [4096] Standard Stream IO [1378] Standard Random IO RWD[1333] Standard Random IO RWS[2103]
Block Size [4096] Loop Size [65536] Standard Stream IO [18595] Standard Random IO RWD[20152] Standard Random IO RWS[19827]
On my Linux box (700 Mhz PIII, 7200 RPM IBM Drive running Gentoo Linux with EXT3 file system and hdparm tuning done.)
Block Size [4096] Loop Size [4096] Standard Stream IO [194] <-- low probably because of the HD cache Standard Random IO RWD[111689] Standard Random IO RWS[108569]
Block Size [4096] Loop Size [65536] Standard Stream IO [61573] Standard Random IO RWD[1760954] Standard Random IO RWS[1779748]
I expected the Linux box to have better IO performance because of the differences in the disk specifications. (And I see this with the stream IO test). However, the RandomAccess performance on Linux (Sun Java 1.4.1_05) is horrible compared to the FileOutputStream performance.
Notice that the ratio of stream IO is about 3x between Mac and Linux (Linux is 3x slower) but with random IO Linux is more than 80x slower than on the Macintosh.
Something must be wrong with the Sun JDK 1.4.1_05 implementation on Linux. I should not take 29 minutes to write a 256 Meg file to disk!
If anyone would like to run the program, let me know and I'll send it to you via email.
I would be very interested in seeing results on other Linux configurations and on Windows.
Regards,
Randy
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