Can't seem to get the right buffer size set

[mike]

To try to maximize the possibility I've set the following:

        fastcgi_buffer_size 16k;
        fastcgi_buffers 64 16k;
        fastcgi_busy_buffers_size 16k;

This is for requests to .php scripts

Even this, just in case:

        proxy_buffer_size 16k;
        proxy_buffers 64 16k;
        gzip_buffers 64 16k;

Now by reading past emails this looks like I should be able to buffer

fastcgi: (64 * 16) + 16 = 1040k per request
proxy: (64 * 16) + 16 = 1040k per request
even gzip 64 * 16 = 1024k

I am sending only 512k POST with a few headers - definately under a megabyte.

I also have these, not sure if it matters.

        client_max_body_size 251m;
        client_header_buffer_size 8k;
        client_body_buffer_size 256k;
        large_client_header_buffers 16 8k;

Still getting this:

2008/11/25 00:20:58 [warn] 24362#0: *195 a client request body is
buffered to a temporary file /var/lib/nginx/body/0000000002, client:
1.2.3.4, server: foo.com, request: "POST /u/temp.php HTTP/1.1", host:
"foo.com"

Is there a possibility the request is larger or something else is
going on? Is there anything I can log to check the full size of the
request?