Provided by: systemtap-doc_2.3-1ubuntu1.4_all 

NAME
probe::ioscheduler.elv_next_request - Fires when a request is retrieved from the request queue
SYNOPSIS
ioscheduler.elv_next_request
VALUES
name
Name of the probe point
elevator_name
The type of I/O elevator currently enabled
SystemTap Tapset Reference March 2016 PROBE::IOSCHEDULER(3stap)