use bpf_log2l helper

Limnotation · Sep 21, 2015 · 30abd81 · 30abd81
1 parent 8f63810
commit 30abd81
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Showing 2 changed files with 2 additions and 48 deletions.
diff --git a/examples/bitehist.c b/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:https://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)++;
 

diff --git a/examples/vfsreadlat.c b/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:https://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);