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#! /usr/bin/env stap
#
# Copyright (C) 2010 Red Hat, Inc.
# By Dominic Duval, Red Hat Inc.
# dduval@redhat.com
#
# Keeps track of seeks on devices.
# Shows how to use hist_log.
#
# USAGE: stap deviceseeks.stp
#
global seeks, oldsec
@define q_cast(var) %( @cast(@var, "request_queue", "kernel") %)
probe ioblock_trace.request {
if (size == 0) next
%( $# == 1 %? if (devname !~ @1) next %) // reject mismatching device names
# Newer kernels remove the $q parameter from tracepoint
# For 5.12 and newer get the q from $bio->bi_bdev->bd_disk->queue
# For 5.11 get queue from $bio->bi_disk->queue
queue = @defined ($q) ? $q
: @choose_defined($bio->bi_bdev->bd_disk->queue, $bio->bi_disk->queue)
sectorsize = (@defined(@q_cast(queue)->limits->logical_block_size) ?
@q_cast(queue)->limits->logical_block_size :
(@defined(@q_cast(queue)->logical_block_size) ?
@q_cast(queue)->logical_block_size :
@q_cast(queue)->hardsect_size ))
# printf("%s %s\n", devname, rw ? "w" : "r")
sec = sector
seeks[devname] <<< sec - oldsec[devname]
oldsec[devname] = sector + (size/sectorsize)
}
probe timer.s(10), end, error {
printf("\n")
foreach ([devname] in seeks- limit 5) {
printf("Device: %s\n", devname)
println(@hist_log(seeks[devname]))
}
delete seeks
}
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