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| author | Eric Dumazet <edumazet@google.com> | 2020-08-13 19:06:43 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-08-14 00:11:14 +0200 |
| commit | 94c7eb54c4b8e81618ec79f414fe1ca5767f9720 (patch) | |
| tree | 448b3fe1a37f74eb9308781e1957e557d18afb3d | |
| parent | Revert "ipv4: tunnel: fix compilation on ARCH=um" (diff) | |
| download | linux-94c7eb54c4b8e81618ec79f414fe1ca5767f9720.tar.xz linux-94c7eb54c4b8e81618ec79f414fe1ca5767f9720.zip | |
random32: add a tracepoint for prandom_u32()
There has been some heat around prandom_u32() lately, and some people
were wondering if there was a simple way to determine how often
it was used, before considering making it maybe 10 times more expensive.
This tracepoint exports the generated pseudo random value.
Tested:
perf list | grep prandom_u32
random:prandom_u32 [Tracepoint event]
perf record -a [-g] [-C1] -e random:prandom_u32 sleep 1
[ perf record: Woken up 0 times to write data ]
[ perf record: Captured and wrote 259.748 MB perf.data (924087 samples) ]
perf report --nochildren
...
97.67% ksoftirqd/1 [kernel.vmlinux] [k] prandom_u32
|
---prandom_u32
prandom_u32
|
|--48.86%--tcp_v4_syn_recv_sock
| tcp_check_req
| tcp_v4_rcv
| ...
--48.81%--tcp_conn_request
tcp_v4_conn_request
tcp_rcv_state_process
...
perf script
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/trace/events/random.h | 17 | ||||
| -rw-r--r-- | lib/random32.c | 2 |
2 files changed, 19 insertions, 0 deletions
diff --git a/include/trace/events/random.h b/include/trace/events/random.h index 32c10a515e2d..9570a10cb949 100644 --- a/include/trace/events/random.h +++ b/include/trace/events/random.h @@ -307,6 +307,23 @@ TRACE_EVENT(urandom_read, __entry->pool_left, __entry->input_left) ); +TRACE_EVENT(prandom_u32, + + TP_PROTO(unsigned int ret), + + TP_ARGS(ret), + + TP_STRUCT__entry( + __field( unsigned int, ret) + ), + + TP_fast_assign( + __entry->ret = ret; + ), + + TP_printk("ret=%u" , __entry->ret) +); + #endif /* _TRACE_RANDOM_H */ /* This part must be outside protection */ diff --git a/lib/random32.c b/lib/random32.c index 3d749abb9e80..932345323af0 100644 --- a/lib/random32.c +++ b/lib/random32.c @@ -39,6 +39,7 @@ #include <linux/random.h> #include <linux/sched.h> #include <asm/unaligned.h> +#include <trace/events/random.h> #ifdef CONFIG_RANDOM32_SELFTEST static void __init prandom_state_selftest(void); @@ -82,6 +83,7 @@ u32 prandom_u32(void) u32 res; res = prandom_u32_state(state); + trace_prandom_u32(res); put_cpu_var(net_rand_state); return res; |