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Linux io_uring Dual-Ring Buffers
Inspect the lock-free Submission Queue (SQ) and Completion Queue (CQ) mapped in shared memory. Compare batch syscall dispatch with zero-syscall SQPOLL kernel thread polling.
Execution Mode
Default (io_uring_enter)
System Calls Issued
0
Ops Completed
0
SQ Ring Usage
0 / 8
CQ Ring Usage
0 / 16
Submission Queue (SQ) Ring(Shared Memory 64-byte SQEs)
Head: 0 · Tail: 0
Slot 0
Empty
TAIL
Slot 1
Empty
Slot 2
Empty
Slot 3
Empty
Slot 4
Empty
Slot 5
Empty
Slot 6
Empty
Slot 7
Empty
Producer (User Space) advances tail with smp_store_release(). Consumer (Kernel) advances head with smp_load_acquire().
Completion Queue (CQ) Ring(Shared Memory 16-byte CQEs)
Head: 0 · Tail: 0
CQ 0
Empty
TAIL
CQ 1
Empty
CQ 2
Empty
CQ 3
Empty
CQ 4
Empty
CQ 5
Empty
CQ 6
Empty
CQ 7
Empty
Producer (Kernel) writes result and advances tail. Consumer (User Space) reaps result and advances head.
KERNEL DISPATCHuser space waiting
Ready. Enqueue an SQE into shared memory or toggle SQPOLL mode.
Observe: In default mode, io_uring_enter() consumes a system call. In SQPOLL mode, the kernel thread processes SQEs directly from shared memory with 0 system calls.