Bug 29991 - write to the ext2fs is slow
write to the ext2fs is slow
Status: CLOSED NOTABUG
Product: Red Hat Linux
Classification: Retired
Component: e2fsprogs (Show other bugs)
6.0
i686 Linux
high Severity high
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Assigned To: Florian La Roche
Aaron Brown
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Depends On:
Blocks:
  Show dependency treegraph
 
Reported: 2001-02-28 04:39 EST by Vaibhav A Nalawade
Modified: 2005-10-31 17:00 EST (History)
0 users

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Doc Type: Bug Fix
Doc Text:
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Clone Of:
Environment:
Last Closed: 2001-02-28 04:43:19 EST
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Attachments (Terms of Use)
tar file (10.00 KB, application/octet-stream)
2001-02-28 04:43 EST, Vaibhav A Nalawade
no flags Details

  None (edit)
Description Vaibhav A Nalawade 2001-02-28 04:39:33 EST
Hi ,

    I have the product running on Linux 6.0 (egcs 2.91.66) . 

	In this product there is necessity to pre-allocate the file used for
storing. This
preallocation is achieved by putting 0 (zero's) in the file till the
desired size of the file . 
The file is then used to store structures(objects or records) . If I
pre-allocate the file the 
application which puts objects in the file becomes slow as compared to
wrting in a non
pre-allocated file. 

	I have attached a tar(compressed test file) that shows this degradation in
performance . 

	The tar file contains c program file create.c which when compiled and run
with 
-i(preallocate) option takes more time than without -i option . I have put
time in the file so just
running runtest script .
	I have a work around that I have done in the testcase file recreate.c .
Instead of
filling the whole file with 0 (zero's) I jump to the desired size of the
file offset and put 0 (zero's).
This shows no degradation. But I was not able to find the reason behind
degradation. 

	Moreover even after this work around the test case takes twice the time it
takes on Solaris or Aix machines .  

Can I have the ext2fs tunning paramaters which will improve the
performance.

	
Thanks ,
Vaibhav Nalawade .
Comment 1 Vaibhav A Nalawade 2001-02-28 04:43:10 EST
Created attachment 11322 [details]
tar file
Comment 2 Florian La Roche 2001-03-28 07:24:59 EST
If you seek to a specific place, you create "holes" in the file that don't have
to be written, so
that should be faster than actually writing the file to disc. Seems to be all
fine for me.


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