icstat.bt

#!/usr/local/bin/bpftrace
/*
 * icstat - Inode cache hit statistics.
 *
 * See BPF Performance Tools, Chapter 8, for an explanation of this tool.
 *
 * Copyright (c) 2019 Brendan Gregg.
 * Licensed under the Apache License, Version 2.0 (the "License").
 * This was originally created for the BPF Performance Tools book
 * published by Addison Wesley. ISBN-13: 9780136554820
 * When copying or porting, include this comment.
 *
 * 02-Feb-2019  Brendan Gregg   Created this.
 */

BEGIN
{
	printf("Tracing icache lookups... Hit Ctrl-C to end.\n");
	printf("%10s %10s %5s\n", "REFS", "MISSES", "HIT%");
}

kretprobe:find_inode_fast
{
	@refs++;
	if (retval == 0) {
		@misses++;
	}
}

interval:s:1
{
	$hits = @refs - @misses;
	$percent = @refs > 0 ? 100 * $hits / @refs : 0;
	printf("%10d %10d %4d%%\n", @refs, @misses, $percent);
	clear(@refs);
	clear(@misses);
}

END
{
	clear(@refs);
	clear(@misses);
}