Sendfile Threshold Configuration

[roq3]

The sendfile threshold is currently hardcoded to 200 KB in HttpResponseImpl.cc:312, making it impossible for users to tune this performance parameter for their specific workloads. This value determines the minimum file size for using the sendfile() syscall - files larger than this threshold use sendfile for efficiency, while smaller files are sent as regular responses.

Current Approach

Currently, the threshold is hardcoded:

if (HttpAppFrameworkImpl::instance().useSendfile() && length > 1024 * 200)
// TODO : Is 200k an appropriate value? Or set it to be configurable

This hardcoded value may not be optimal for all use cases:

• Small VPS deployments might benefit from a larger threshold (e.g., 1MB) to reduce system calls
• Large-scale servers might prefer a smaller threshold (e.g., 100KB) for better memory control
• Different workloads (static files vs. media streaming) have different optimal values

This would be a simple but valuable enhancement. Should it be configurable, and not hardcoded? Thoughts?