Re: updating HFS+ inode info. on open() call
Re: updating HFS+ inode info. on open() call
- Subject: Re: updating HFS+ inode info. on open() call
- From: Ian Brown <email@hidden>
- Date: Wed, 6 Mar 2002 20:56:47 -0800
I am trying to store statistical information with files that persists
across reboots. Theoretically it looks like an attribute record
(HFSPlusAttrInlineData) would be the best place to put this information,
however it does not look like those work yet (correct me if I am wrong.)
FIRST:
I want to store a counter with each file (or file metadata) counting
open()'s. I can then set them to zero and run filesystem benchmarks and
get file access statistics. "But," they say, "this can be done by
taking a trace." I know, but it would not show me how to store
statistical information with files. Why do I want to do this then?
NEXT:
I will be able to store predictive information with files.
Specifically I would like to store a reference to the file that gets
accessed next. I plan to do this at the time of the next open().
This will give me file grouping information and predictive
pre-fetching information.
The situation with mmap() had not crossed my mind, however I am not
sure if it is an issue with what I am ultimately trying to do.
Ian
What exactly are you trying to do?
Is this total number of open() calls for a file counter? Does it
persist across reboot?
Are you planning on decrementing the counter when close() is called?
If so, What do you intend to do for the case
open()
mmap()
close()
Now you counter goes to 0, but the inode is still in use...
--Umesh
--
Umesh Vaishampayan Apple Computer, Inc.
Mac OS X Kernel Ph: (408) 974 0229
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