Files
linux/lib
Eric Dumazet 94c7eb54c4 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>
2020-08-13 15:11:14 -07:00
..
2020-07-31 18:08:59 +10:00
2020-05-24 20:48:11 +02:00
2018-08-16 12:14:42 -07:00
2020-06-01 08:23:42 -04:00
2017-02-24 17:46:57 -08:00
2020-05-07 14:54:26 +08:00
2018-10-16 13:45:44 +02:00
2020-06-15 18:22:43 -07:00
2018-06-27 18:58:49 +03:00
2020-06-29 10:02:23 +02:00
2018-10-15 16:31:29 -04:00
2020-06-04 19:06:28 -07:00
2017-08-15 09:02:07 -07:00