Re: VFS layer filesytem tracking
On Wed, Dec 8, 2010 at 8:00 AM, sanoj wrote:
> Hello all,
> I want to track the read/write operations for a particular inode at the vfs
> layer.
> I added the following structure as a field to struct inode.
> struct meta_info
> {
> unsigned int read_count;
> unsigned int write_count;
> };
Looking at the fields it seems you want this only incore...and I guess
you want to count how many reads or writes came to a particular file.
> This caused a problem in mounting the root device , what could be the cause
> ?
Can you tell us what was the error/problem ? Stack trace would be better.
> Am i allowed modify the struct inode by adding a new field ?
Sure :-) ... you are allowed to modify incore ondisk anything as long
as you make code understand those structures (or if you are adding
something in spare bytes which might get ignored). If you change
something ondisk structure you will need to fix other userspace
utilities which may parse this (in the worst case throw away your old
filesystem and create new one if it changes the size of ondisk inode).
> Also, i would like to know if there are any existing mechanisms that can
> help me track the workload .
> at various levels
> Thanks,
HTH
> sanoj
>
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Re: VFS layer filesytem tracking
On Wed, Dec 8, 2010 at 11:00 AM, sanoj wrote:
> Hello all,
> I want to track the read/write operations for a particular inode at the vfs
> layer.
> I added the following structure as a field to struct inode.
> struct meta_info
> {
> unsigned int read_count;
> unsigned int write_count;
> };
> This caused a problem in mounting the root device , what could be the cause
> ?
> Am i allowed modify the struct inode by adding a new field ?
> Also, i would like to know if there are any existing mechanisms that can
> help me track the workload .
> at various levels
> Thanks,
> sanoj
There are 2 instances of inode I believe.
One is the on disk layout, and one is the ram layout.
You can modify the ram layout to your hearts content, but the disk
layout you have to be very precise with.
The trouble is the ram instance will of course be free'd from time to
time, so you can't keep data in there forever.
I don't positively recall the lifetime rules for the ram instance, but
I think as long as a file is open, the inode is kept in RAM. I also
think there are ways to lock an inode in RAM if you need it RAM
resident over multiple open/close sessions.
Greg
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Re: VFS layer filesytem tracking
On Wed, Dec 8, 2010 at 23:00, sanoj wrote: > Hello all, > I want to track the read/write operations for a particular inode at the vfs > layer. Try inotify -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecar...@nl.linux.org Please read the FAQ at http://kernelnewbies.org/FAQ
VFS layer filesytem tracking
Hello all,
I want to track the read/write operations for a particular inode at the vfs
layer.
I added the following structure as a field to struct inode.
struct meta_info
{
unsigned int read_count;
unsigned int write_count;
};
This caused a problem in mounting the root device , what could be the cause
?
Am i allowed modify the struct inode by adding a new field ?
Also, i would like to know if there are any existing mechanisms that can
help me track the workload .
at various levels
Thanks,
sanoj
