nginx reverse proxy causing TCP queuing spikes

[Grant]

I've been struggling with http response time slowdowns and
corresponding spikes in my TCP Queuing graph in munin.  I'm using
nginx as a reverse proxy to apache which then hands off to my backend,
and I think the proxy_read_timeout line in my nginx config is at least
contributing to the issue.  Here is all of my proxy config:

proxy_read_timeout 60m;
proxy_pass http://127.0.0.1:8080;

I think this means I'm leaving connections open for 60 minutes after
the last server response which sounds like a bad thing.  However, some
of my admin pages need to run for a long time while they wait for the
server-side stuff to execute.  I only use the proxy_read_timeout
directive on my admin locations and I'm experiencing the TCP spikes
and http slowdowns during the exact hours that the admin stuff is in
use.

- Grant