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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /samples/bpf/tracex3_kern.c | |
parent | Initial commit. (diff) | |
download | linux-upstream.tar.xz linux-upstream.zip |
Adding upstream version 6.1.76.upstream/6.1.76upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | samples/bpf/tracex3_kern.c | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/samples/bpf/tracex3_kern.c b/samples/bpf/tracex3_kern.c new file mode 100644 index 000000000..af235bd66 --- /dev/null +++ b/samples/bpf/tracex3_kern.c @@ -0,0 +1,102 @@ +/* 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 + * License as published by the Free Software Foundation. + */ +#include <linux/skbuff.h> +#include <linux/netdevice.h> +#include <linux/version.h> +#include <uapi/linux/bpf.h> +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> + +struct start_key { + dev_t dev; + u32 _pad; + sector_t sector; +}; + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __type(key, long); + __type(value, u64); + __uint(max_entries, 4096); +} my_map SEC(".maps"); + +/* from /sys/kernel/tracing/events/block/block_io_start/format */ +SEC("tracepoint/block/block_io_start") +int bpf_prog1(struct trace_event_raw_block_rq *ctx) +{ + u64 val = bpf_ktime_get_ns(); + struct start_key key = { + .dev = ctx->dev, + .sector = ctx->sector + }; + + bpf_map_update_elem(&my_map, &key, &val, BPF_ANY); + return 0; +} + +static unsigned int log2l(unsigned long long n) +{ +#define S(k) if (n >= (1ull << k)) { i += k; n >>= k; } + int i = -(n == 0); + S(32); S(16); S(8); S(4); S(2); S(1); + return i; +#undef S +} + +#define SLOTS 100 + +struct { + __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); + __uint(key_size, sizeof(u32)); + __uint(value_size, sizeof(u64)); + __uint(max_entries, SLOTS); +} lat_map SEC(".maps"); + +/* from /sys/kernel/tracing/events/block/block_io_done/format */ +SEC("tracepoint/block/block_io_done") +int bpf_prog2(struct trace_event_raw_block_rq *ctx) +{ + struct start_key key = { + .dev = ctx->dev, + .sector = ctx->sector + }; + + u64 *value, l, base; + u32 index; + + value = bpf_map_lookup_elem(&my_map, &key); + if (!value) + return 0; + + u64 cur_time = bpf_ktime_get_ns(); + u64 delta = cur_time - *value; + + bpf_map_delete_elem(&my_map, &key); + + /* the lines below are computing index = log10(delta)*10 + * using integer arithmetic + * index = 29 ~ 1 usec + * index = 59 ~ 1 msec + * index = 89 ~ 1 sec + * index = 99 ~ 10sec or more + * log10(x)*10 = log2(x)*10/log2(10) = log2(x)*3 + */ + l = log2l(delta); + base = 1ll << l; + index = (l * 64 + (delta - base) * 64 / base) * 3 / 64; + + if (index >= SLOTS) + index = SLOTS - 1; + + value = bpf_map_lookup_elem(&lat_map, &index); + if (value) + *value += 1; + + return 0; +} +char _license[] SEC("license") = "GPL"; +u32 _version SEC("version") = LINUX_VERSION_CODE; |