What does sendfile_max_chunk do?

[Costello]

Hello,

Once again I am in need of your help!
I'm looking to document directives that are missing from the Wiki.
I found loads in the source code, especially thanks to Manlio Perillo.

I've stumbled upon "sendfile_max_chunk" declared in ngx_http_core_module.c.
I investigated what this does, here is what I found:
- it's a size value directive
- it's set to 0 by default (presumably this means no maximum size)

I'm not sure what it does. 
It is probably somewhat connected to the use of sendfile, my understanding is as follows:
"This directive defines the maximum size of chunks to be read from the storage system when using sendfile".
Is this a correct and accurate definition? Could anyone provide more information?

Thanks a lot in advance for helping me clear it out!

Best regards,
Costello

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,86566,86566#msg-86566