That's not really random IO from a single process. That's 1 MB of sequential IO from multiple processes, in series.
You really need something lower-level, something maybe like this:
Compile that with "-m64" to get a 64-bit binary that can easily handle devices > 2GB, and run like this on Linux:
or this on Solaris:
Also of note, if you're reading small chunks (8K or so, most common page size), and your storage device has a large read-ahead setting, you'll get much slower performance than you'd otherwise expect as each 8K read can cause the disk controllers to read a whole lot more than 8K per read.
You can get some strange effects with high-speed disk systems. Try to malloc() a 1 GB buffer, and read into it from a high-speed storage system without actually setting the memory you malloc()'d to zero. The data can come in from disk faster than your system's virtual memory system can create the pages to put it into.
And then you can turn around and do something pathologically bad and get only a few KB/sec from that same storage.
Hi Unix gurus,
I have a file. I need to insert sequential number at the starting of the file. Fields are delimited by "|". I know the starting number.
Example:
File is as follows
|123|4test|test
|121|2test|test
|x12|1test|test
|vd123|5test|test
starting number is : 120
... (7 Replies)
We have to convert a sequential file to a 80 char line sequential file (HP UX platform).The sequential file contains special characters. which after conversion of the file to line sequential are getting coverted into "new line" or "tab" and file is getting distorted. Is there any way to read these... (2 Replies)
So, I've got a ton of files that I want to go through (ie something like 300,000), and they're all labeled sequentially. However I'm not 100% positive that they are all there.
Is there any way of running through a sequence of numbers, checking if the file is in the folder, if not appending it... (2 Replies)
Hi
I am working on a script which needs to scan a sequential file and fetch the row where 2nd column = 'HUB'
Can any one help me with this...
Thanks (1 Reply)
Hi,
I have a task where i need to scan second column of seuential file and fetch first 3 digits of that column
For e.g. FOLLOWING IS THE SAMPLE FOR MY SEQUENTIAL FILE
AU_ID ACCT_NUM CRNCY_CDE
THHSBC001 30045678 THB
THHSBC001 10154267 THB
THHSBC001 ... (2 Replies)
Dear linux experts,
I'd like to ask for your support, I've read some posts in this forum about files comparison but haven't found what I'm looking for. I need to create a sequential script to compare row-by-row one file with 34 similar files but without success so far. This is what I get:
... (2 Replies)
Hi
I have a file sequential way i.e. written in contineous mode and the Record Seperator is AM from which the record is seperated .Now to process I have to make line sequential,and more over record length is not same it varies as per the input address,
AM1234563 John Murray 24 Old streeet old... (5 Replies)
I have a csv flatfile with a few million rows. I need to replace a field (field number is 85) in the file with a sequential number.
As an example, let's assume there are only 4 fields in the file:
A,A,,32
A,A,,27
A,B,,43
C,C,,354
If I wanted to amend the 3rd field in this way my... (2 Replies)
Hi,
I have a directory structure like below
Directoryname create time
d1 12:00
d2 12:05
d3 12:08
I want to read the directories based on timestamp.That is oldest directory must be read first and kick off certain process.
... (7 Replies)
Hello All,
I have two files with me file1.txt and file2.txt
file1.txt has:
333
222
111
file2.txt has
ccc
bbb
aaa
ccc is related to 333 only, bbb is related to 222 only and aaa is related to 111 only.
I have to get the values from each of the file and pass them in the URL... (3 Replies)