Re: [dpdk-dev] [PATCH v2] app/test: add tests for atomic exchanges

[David Marchand <david.marchand@redhat.com>]

On Fri, Oct 18, 2019 at 12:39 AM David Christensen
<drc@linux.vnet.ibm.com> wrote:
>
> The test works by creating a token comprised of random data
> and a CRC8 value, using the rte_atomicXX_exchange to exchange
> the new token for a previously generated token, and then
> verifying that the exchanged data is intact (i.e. the CRC8
> is still correct for the data).

Thanks for working on this, there is a build error reported by the CI,
see below.
If you have a github account, you can set up travis.
Travis will compile your patch through the different targets we have
in it + run the unit tests.


>
> Signed-off-by: David Christensen <drc@linux.vnet.ibm.com>
> ---
>  app/test/test_atomic.c | 173 ++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 171 insertions(+), 2 deletions(-)
>
> diff --git a/app/test/test_atomic.c b/app/test/test_atomic.c
> index 43be30ec0..4a818b6d5 100644
> --- a/app/test/test_atomic.c
> +++ b/app/test/test_atomic.c
> @@ -1,10 +1,12 @@
>  /* SPDX-License-Identifier: BSD-3-Clause
>   * Copyright(c) 2010-2014 Intel Corporation
> + * Copyright(c) 2019 Arm Limited
>   */
>
>  #include <stdio.h>
>  #include <stdint.h>
>  #include <unistd.h>
> +#include <inttypes.h>
>  #include <sys/queue.h>
>
>  #include <rte_memory.h>
> @@ -13,6 +15,8 @@
>  #include <rte_atomic.h>
>  #include <rte_eal.h>
>  #include <rte_lcore.h>
> +#include <rte_random.h>
> +#include <rte_hash_crc.h>
>
>  #include "test.h"
>
> @@ -20,7 +24,7 @@
>   * Atomic Variables
>   * ================
>   *
> - * - The main test function performs three subtests. The first test
> + * - The main test function performs four subtests. The first test
>   *   checks that the usual inc/dec/add/sub functions are working
>   *   correctly:
>   *
> @@ -61,11 +65,26 @@
>   *       atomic_sub(&count, tmp+1);
>   *
>   *   - At the end of the test, the *count* value must be 0.
> + *
> + * - Test "atomic exchange"
> + *
> + *   - Create a 64 bit token that can be tested for data integrity
> + *
> + *   - Invoke ``test_atomic_exchange`` on each lcore.  Before doing
> + *     anything else, the cores wait for a synchronization event.
> + *     Each core then does the follwoing for N iterations:
> + *
> + *       Generate a new token with a data integrity check
> + *       Exchange the new token for previously generated token
> + *       Increment a counter if a corrupt token was received
> + *
> + *   - At the end of the test, the number of corrupted tokens must be 0.
> + *
>   */
>
>  #define NUM_ATOMIC_TYPES 3
>
> -#define N 10000
> +#define N 1000000
>
>  static rte_atomic16_t a16;
>  static rte_atomic32_t a32;
> @@ -216,6 +235,124 @@ test_atomic_dec_and_test(__attribute__((unused)) void *arg)
>         return 0;
>  }
>
> +/*
> + * Helper definitions/variables/functions for
> + * atomic exchange tests
> + */
> +typedef union {
> +       uint16_t u16;
> +       uint8_t  u8[2];
> +} rte_u16_t;
> +
> +typedef union {
> +       uint32_t u32;
> +       uint16_t u16[2];
> +       uint8_t  u8[4];
> +} rte_u32_t;
> +
> +typedef union {
> +       uint64_t u64;
> +       uint32_t u32[2];
> +       uint16_t u16[4];
> +       uint8_t  u8[8];
> +} rte_u64_t;
> +
> +const uint8_t CRC8_POLY = 0x91;
> +uint8_t crc8_table[256];
> +
> +volatile uint16_t token16;
> +volatile uint32_t token32;
> +volatile uint64_t token64;
> +
> +static void
> +build_crc8_table(void)
> +{
> +       uint8_t val;
> +
> +       for (int i = 0; i < 256; i++) {
> +               val = i;
> +               for (int j = 0; j < 8; j++) {
> +                       if (val & 1)
> +                               val ^= CRC8_POLY;
> +                       val >>= 1;
> +               }
> +               crc8_table[i] = val;
> +       }
> +}
> +
> +static uint8_t
> +get_crc8(uint8_t *message, int length)
> +{
> +       uint8_t crc = 0;
> +
> +       for (int i = 0; i < length; i++)
> +               crc = crc8_table[crc ^ message[i]];
> +       return crc;
> +}
> +
> +/*
> + * The atomic exchange test sets up a token in memory and
> + * then spins up multiple lcores whose job is to generate
> + * new tokens, exchange that new token for the old one held
> + * in memory, and then verify that the old token is still
> + * valid (i.e. the exchange did not corrupt the token).
> + *
> + * A token is made up of random data and 8 bits of crc
> + * covering that random data.  The following is an example
> + * of a 64bit token.
> + *
> + * +------------+------------+
> + * | 63      56 | 55       0 |
> + * +------------+------------+
> + * |    CRC8    |    Data    |
> + * +------------+------------+
> + */
> +static int
> +test_atomic_exchange(__attribute__((unused)) void *arg)
> +{
> +       rte_u16_t nt16, ot16; /* new token, old token */
> +       rte_u32_t nt32, ot32;
> +       rte_u64_t nt64, ot64;
> +
> +       /* Wait until all of the other threads have been dispatched */
> +       while (rte_atomic32_read(&synchro) == 0)
> +               ;
> +
> +       /*
> +        * Let the battle begin! Every thread attempts to steal the current
> +        * token with an atomic exchange operation and install its own newly
> +        * generated token. If the old token is valid (i.e. it has the
> +        * appropriate crc32 hash for the data) then the test iteration has
> +        * passed.  If the token is invalid, increment the counter.
> +        */
> +       for (int i = 0; i < N; i++) {
> +
> +               /* Test 64bit Atomic Exchange */
> +               nt64.u64 = rte_rand();
> +               nt64.u8[7] = get_crc8(&nt64.u8[0], sizeof(nt64) - 1);
> +               ot64.u64 = rte_atomic64_exchange(&token64, nt64.u64);
> +               if (ot64.u8[7] != get_crc8(&ot64.u8[0], sizeof(ot64) - 1))
> +                       rte_atomic64_inc(&count);
> +
> +               /* Test 32bit Atomic Exchange */
> +               nt32.u32 = (uint32_t)rte_rand();
> +               nt32.u8[3] = get_crc8(&nt32.u8[0], sizeof(nt32) - 1);
> +               ot32.u32 = rte_atomic32_exchange(&token32, nt32.u32);
> +               if (ot32.u8[3] != get_crc8(&ot32.u8[0], sizeof(ot32) - 1))
> +                       rte_atomic64_inc(&count);
> +
> +               /* Test 16bit Atomic Exchange */
> +               nt16.u16 = (uint16_t)rte_rand();
> +               nt16.u8[1] = get_crc8(&nt16.u8[0], sizeof(nt16) - 1);
> +               ot16.u16 = rte_atomic16_exchange(&token16, nt16.u16);
> +               if (ot16.u8[1] != get_crc8(&ot16.u8[0], sizeof(ot16) - 1))
> +                       te_atomic64_inc(&count);

  CC test_atomic.o
/home-local/jenkins-local/jenkins-agent/workspace/Apply-Custom-Patch-Set/dpdk/app/test/test_atomic.c:
In function ‘test_atomic_exchange’:
/home-local/jenkins-local/jenkins-agent/workspace/Apply-Custom-Patch-Set/dpdk/app/test/test_atomic.c:349:4:
error: implicit declaration of function ‘te_atomic64_inc’; did you
mean ‘rte_atomic64_inc’? [-Werror=implicit-function-declaration]
    te_atomic64_inc(&count);
    ^~~~~~~~~~~~~~~
    rte_atomic64_inc
/home-local/jenkins-local/jenkins-agent/workspace/Apply-Custom-Patch-Set/dpdk/app/test/test_atomic.c:349:4:
error: nested extern declaration of ‘te_atomic64_inc’
[-Werror=nested-externs]
/home-local/jenkins-local/jenkins-agent/workspace/Apply-Custom-Patch-Set/dpdk/app/test/test_atomic.c:
At top level:
cc1: error: unrecognized command line option
‘-Wno-address-of-packed-member’ [-Werror]
cc1: all warnings being treated as errors
/


> +       }
> +
> +       return 0;
> +}
> +
> +
>  static int
>  test_atomic(void)
>  {
> @@ -340,6 +477,38 @@ test_atomic(void)
>                 return -1;
>         }
>
> +       /*
> +        * Test 16/32/64bit atomic exchange.
> +        */
> +       rte_u64_t t;
> +
> +       printf("exchange test\n");
> +
> +       rte_atomic32_clear(&synchro);
> +       rte_atomic64_clear(&count);
> +
> +       /* Generate the CRC8 lookup table */
> +       build_crc8_table();
> +
> +       /* Create the initial tokens used by the test */
> +       t.u64 = rte_rand();
> +       token16 = (get_crc8(&t.u8[0], sizeof(token16) - 1) << 8)
> +               | (t.u16[0] & 0x00ff);
> +       token32 = ((uint32_t)get_crc8(&t.u8[0], sizeof(token32) - 1) << 24)
> +               | (t.u32[0] & 0x00ffffff);
> +       token64 = ((uint64_t)get_crc8(&t.u8[0], sizeof(token64) - 1) << 56)
> +               | (t.u64 & 0x00ffffffffffffff);
> +
> +       rte_eal_mp_remote_launch(test_atomic_exchange, NULL, SKIP_MASTER);
> +       rte_atomic32_set(&synchro, 1);
> +       rte_eal_mp_wait_lcore();
> +       rte_atomic32_clear(&synchro);
> +
> +       if (rte_atomic64_read(&count) > 0) {
> +               printf("Atomic exchange test failed\n");
> +               return -1;
> +       }
> +
>         return 0;
>  }
>
> --
> 2.18.1
>


-- 
David Marchand