use bpf_log2l helper

examples/bitehist.c

@@ -2,7 +2,6 @@
  * bitehist.c	Block I/O size histogram.
  *		For Linux, uses BCC, eBPF. See .py file.
  *
- * Based on eBPF sample tracex2 by Alexi Starovoitov.
  * Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of version 2 of the GNU General Public
@@ -16,31 +15,9 @@
 
 BPF_TABLE("array", int, u64, dist, 64);
 
-static unsigned int log2(unsigned int v)
-{
-	unsigned int r;
-	unsigned int shift;
-
-	r = (v > 0xFFFF) << 4; v >>= r;
-	shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
-	shift = (v > 0xF) << 2; v >>= shift; r |= shift;
-	shift = (v > 0x3) << 1; v >>= shift; r |= shift;
-	r |= (v >> 1);
-	return r;
-}
-
-static unsigned int log2l(unsigned long v)
-{
-	unsigned int hi = v >> 32;
-	if (hi)
-		return log2(hi) + 32 + 1;
-	else
-		return log2(v) + 1;
-}
-
 int kprobe__blk_account_io_completion(struct pt_regs *ctx, struct request *req)
 {
-	int index = log2l(req->__data_len / 1024);
+	int index = bpf_log2l(req->__data_len / 1024);
 	u64 *leaf = dist.lookup(&index);
 	if (leaf) (*leaf)++;
 

examples/vfsreadlat.c

@@ -2,7 +2,6 @@
  * vfsreadlat.c		VFS read latency distribution.
  *			For Linux, uses BCC, eBPF. See .py file.
  *
- * Based on eBPF sample tracex2 by Alexi Starovoitov.
  * Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of version 2 of the GNU General Public
@@ -16,28 +15,6 @@
 BPF_HASH(start, u32);
 BPF_TABLE("array", int, u64, dist, 64);
 
-static unsigned int log2(unsigned int v)
-{
-	unsigned int r;
-	unsigned int shift;
-
-	r = (v > 0xFFFF) << 4; v >>= r;
-	shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
-	shift = (v > 0xF) << 2; v >>= shift; r |= shift;
-	shift = (v > 0x3) << 1; v >>= shift; r |= shift;
-	r |= (v >> 1);
-	return r;
-}
-
-static unsigned int log2l(unsigned long v)
-{
-	unsigned int hi = v >> 32;
-	if (hi)
-		return log2(hi) + 32 + 1;
-	else
-		return log2(v) + 1;
-}
-
 int do_entry(struct pt_regs *ctx)
 {
 	u32 pid;
@@ -59,7 +36,7 @@ int do_return(struct pt_regs *ctx)
 
 	if (tsp != 0) {
 		delta = bpf_ktime_get_ns() - *tsp;
-		int index = log2l(delta / 1000);
+		int index = bpf_log2l(delta / 1000);
 		u64 *leaf = dist.lookup(&index);
 		if (leaf) (*leaf)++;
 		start.delete(&pid);