Re: [dpdk-dev] [PATCH v2] eal/ppc64: improve rte_rdtsc with ppc_get_timebase

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

On Fri, Jan 31, 2020 at 11:04 PM Thinh Tran <thinhtr@linux.vnet.ibm.com> wrote:
>
>   __ppc_get_timebase() is GNU extension and is more efficient
>
>   v2: Advoid breaking other ppc_64 flatforms. The __ppc_get_timebase()
>       seems to be specific to powerpc platform and with GLIBC.

dpdk only supports glibc at the moment.
https://doc.dpdk.org/guides/linux_gsg/sys_reqs.html#system-software

Now the 1M$ question is which C library are you using and on which platform :-).


>
> Signed-off-by: Thinh Tran <thinhtr@linux.vnet.ibm.com>
> ---
>  lib/librte_eal/common/include/arch/ppc_64/rte_cycles.h | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/lib/librte_eal/common/include/arch/ppc_64/rte_cycles.h b/lib/librte_eal/common/include/arch/ppc_64/rte_cycles.h
> index 8f2e98642..1c3fd556e 100644
> --- a/lib/librte_eal/common/include/arch/ppc_64/rte_cycles.h
> +++ b/lib/librte_eal/common/include/arch/ppc_64/rte_cycles.h
> @@ -14,6 +14,9 @@ extern "C" {
>
>  #include <rte_byteorder.h>
>  #include <rte_common.h>
> +#if defined(__powerpc__) && defined(__GLIBC__)
> +#include <sys/platform/ppc.h>
> +#endif

libc headers must come first:
https://doc.dpdk.org/guides/contributing/coding_style.html#header-includes

Why do you need the __powerpc__ guard?

>
>  /**
>   * Read the time base register.
> @@ -24,6 +27,9 @@ extern "C" {
>  static inline uint64_t
>  rte_rdtsc(void)
>  {
> +#if defined(__powerpc__) && defined(__GLIBC__)
> +       return __ppc_get_timebase();
> +#else
>         union {
>                 uint64_t tsc_64;
>                 RTE_STD_C11
> @@ -50,6 +56,7 @@ rte_rdtsc(void)
>                         [tmp] "=r"(tmp)
>                     );
>         return tsc.tsc_64;
> +#endif /* __powerpc__ && __GLIBC__ */
>  }
>
>  static inline uint64_t
> --
> 2.17.1
>


-- 
David Marchand