Proc file vs Device file (performance comparision)

Manishcse113 · 11-17-2009, 07:26 AM

Hi,

I want to share the data from the kernel to a process and from a processs to kernel. At this time I have two choices
a) to create a /proc file from the kernel module and access it for reading and writting from the process.
b) to create a device file from the kernel module and access it for reading and writting from the process.

However, I am not sure, which will give me a better performance.
Do we get any advantage in using the one over the other?

Thanks and regards,
Manish

pixellany · 11-17-2009, 08:29 AM

<<I am not a programmer...>>

It is not clear what you are trying to do.

First, "files" in /proc are really just windows into the kernel data structures in memory. You normally do not want to write to anything in /proc.

Second, a device file (in /dev) is meant to be as the interface to a specific hardware element.

Tell us more about the overall problem.

Manishcse113 · 11-18-2009, 03:22 AM

Hi,

It is a programming query.
Both these type of files can be used for sending data from process to kernel using the write or ioctl function.
In the similar way, process can read data from kernel by using write function which can be implemnted in kernel module for both of these file types.

My query is that is there any advantage in terms of performance in using /dev file type over /proc files.

Thanks and regards,
Manish

sundialsvcs · 11-18-2009, 08:19 AM

Please re-read the previous post. Neither one is appropriate for what you are trying to do.

Read up on "named pipes" and "shared memory segments."

And... "let 'performance' b'dammed." In other words, "

performance... who cares about 'performance.'" No matter what you do these days, it will 'perform.'

johnsfine · 11-18-2009, 09:17 AM

Quote:

Originally Posted by sundialsvcs

Please re-read the previous post. Neither one is appropriate for what you are trying to do.

Do you really think you understand what the OP is trying to do?

I thought it was an interesting question when I first saw this thread (would have answered if I knew the answer). I was annoyed (I expect not as much as the OP) each time someone else who didn't know the answer replied.

Hopefully the clutter in the thread (including my post) won't discourage someone who does know the answer from posting.

cladisch · 11-19-2009, 04:42 AM

Quote:

I want to share the data from the kernel to a process and from a processs to kernel. At this time I have two choices
a) to create a /proc file from the kernel module and access it for reading and writting from the process.
b) to create a device file from the kernel module and access it for reading and writting from the process.

However, I am not sure, which will give me a better performance.

The difference between /proc and /dev is more in how the files relate to the rest to kernel; if you have your own read/write/ioctl callbacks, the implementation is exactly the same, so there is no performance difference at all.