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bitehist.c
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bitehist.c
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/*
* 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, 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
* License as published by the Free Software Foundation.
*
* 15-Aug-2015 Brendan Gregg Created this.
*/
#include <uapi/linux/ptrace.h>
#include <linux/blkdev.h>
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_request(struct pt_regs *ctx, struct request *req)
{
int index = log2l(req->__data_len / 1024);
u64 *leaf = dist.lookup(&index);
if (leaf) (*leaf)++;
return 0;
}