`FF_ZC_SEND` is same as `FF_USE_PAGE_ARRAY`, it will improve performance slightly in some scenarios, need to be tested in combination with real applications.
You can enable both compilation options at the same time or separately.
e.g. unix socket, ipc (with APP on kernel network stack), packet from kernel network stack.
1. Add a new directive kernel_network_stack :
Syntax: kernel_network_stack on | off;
Default: kernel_network_stack off;
Context: http, server
This directive is available only when NGX_HAVE_FF_STACK is defined.
Determines whether server should run on kernel network stack or fstack.
2. Use a simpler and more effective solution to discriminate fstack fd(file descriptor, only socket for now) from kernel fd.