  TCP/IP network stack is irreplaceable for Web services in datacenter
front-end servers, and the demand for which is growing rapidly for emerging
high concurrency network service applications (including Internet, Internet of
Things, mobile Internet, etc.) especially. The existing network stack schemes
often face the dilemma between the data center server resource utilization
(i.e., high CPU efficiency) and application service quality (i.e., low tail
latency). We break this dilemma via a flexible architectural design QStack,
which simultaneously achieves CPU efficiency and low tail latency in user-space
network stack for front-end datacenter server. QStack proposes elastic
framework and application definable full-datapath priority, such that the
network stack collaboration among CPU cores horizontally and coordination
across network layers in fine grained vertically on demand. We prototype QStack
on commodity servers. Testbed experiments demonstrate the effectiveness of
QStack over state-of-the-art user-space network stack designs.
