Asynchronous I/O of shared memory

Asynchronous I/O of shared memory

Post by S3VuIE5pd » Thu, 24 Jan 2008 09:58:03


Dear all,
I'm trying to write a ipc program with shared memory.
It's easy to use, but I find that it's really difficult for me to do
asynchronous I/O with it.
And I can't find much example about it.
Will anyone who knows about it provides any hints?
Thanks in advance.
 
 
 

1. My I's are coming up i's. (lower case)

2. What's the correllation between File I/O's and Disk I/O's

Hi
We have a client that is getting poor response times.
But it's not consistant. One person may have no problems one day while
another is having huge delays, and the next day it's vice versa.
The system we have does a lot of data entry. Depending on the data
entered, a validation against files is required.
We've done a lot of investigation into this, and one thing that we
have noticed is that the number of Disk I/O's increases much faster
than the File I/O's requested.

One thing noticed was they had 9 disks, and disk 1 was going to 70-80%
utilisation (WRKDSKSTS), which in turn caused the other 8 disks to
increase in utilisation.

The iSeries is not reporting damaged objects, files or access paths.

Example
File I/O's Disk I/O's
Action 1: 155 127
Action 2: 230 478
Action 3: 285 400
Action 4: 340 377
Action 5: 420 1220
Action 6: 480 2720

Looking at the above example Actions 1-4 look OK to us (afte review
the program source for Read/Writes and updates). But Actions 5 & 6
have much more Disk I/O than we'd expect.
Should there be some sort of correllation between File I/O's and Disk
I/O's?
What governs Disk I/O is it the OS?
Is there some configuration changes we might be able to make to help
alleviate the problem?

TIA
John

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