Re: [PATCH] [DISCUSS] Optimizing linux applications with the help of the kernel.

From: Benoit Boissinot
Date: Sun Dec 10 2006 - 06:13:35 EST


On 12/10/06, Amit Choudhary <amit2030@xxxxxxxxx> wrote:
Hi All,

I just had an idea for improving the performance of linux applications with some help from the
kernel. Let's say that I have to make a copy of a file. So, I read the input file into a buffer
and then write the buffer to the output file.

In both these cases the same data is coming from kernel_to_user and then from user_to_kernel. If
this can be short-circuited, that is, from kernel_to_kernel then the performance can be increased
a lot.

The psuedocode would be:

fd_inp = open _output_file
fd_out = open _input_file
instruct_kernel to write next data read from fd_inp to fd_out
read fd_out


I think you are describing the splice syscall:

see http://lwn.net/Articles/178199/

regards,

Benoit
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