/usr/share/systemtap/examples/memory
Edit: /usr/share/systemtap/examples/memory/cachestat.stp (1318B)
#!/usr/bin/stap
/* Monitors hits and misses to the page cache and reports a count
every 5 seconds. Based on a bpftrace tool by David Valin. */
// XXX: Rewrite after adding statistical aggregates, new printf to stapbpf.
global active
global hits, misses, total_hits, total_misses
probe begin {
printf("%12s%12s%12s\n", "Hits", "Misses", "% Hits")
}
probe kernel.function("pagecache_get_page") {
active[tid()] = 1
}
probe kernel.function("pagecache_get_page").return {
active[tid()] = 0
}
probe kernel.function("find_get_entry").return {
if (active[tid()]) {
if ($return != 0) hits++ else misses++
}
}
probe timer.s(5) {
h = hits; m = misses
hits = 0; misses = 0
if (h + m > 0) {
percent_hits = h*10000 / (h + m)
printf("%12d%12d", h, m)
printf("%8d.%02d%%\n", percent_hits/100, percent_hits%100)
} else {
printf("%12d%12d", 0, 0)
printf("%8d.%02d%%\n", 0, 0)
}
total_hits += h
total_misses += m
}
probe end {
printf("\nSummary\n")
printf("===\n")
printf("total hits: %12d\n", total_hits)
printf("total misses: %10d\n", total_misses)
if (total_hits+total_misses > 0) {
total_hit_percentage = total_hits*10000/(total_hits+total_misses)
printf("hit percentage: %4d.%02d%%\n",
total_hit_percentage/100, total_hit_percentage%100)
}
}