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Re: [ltt-dev] [PATCH 3/3] lttng: MIPS: Use 64 bit counter for tra

To: David Daney <ddaney@caviumnetworks.com>
Subject: Re: [ltt-dev] [PATCH 3/3] lttng: MIPS: Use 64 bit counter for trace clock on Octeon CPUs.
From: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Date: Tue, 20 Apr 2010 09:56:59 -0400
Cc: ltt-dev@lists.casi.polymtl.ca, linux-mips@linux-mips.org
In-reply-to: <1271722791-27885-4-git-send-email-ddaney@caviumnetworks.com>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <1271722791-27885-1-git-send-email-ddaney@caviumnetworks.com> <1271722791-27885-4-git-send-email-ddaney@caviumnetworks.com>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.18 (2008-05-17)
* David Daney (ddaney@caviumnetworks.com) wrote:
> Cavium Octeon CPUs have a 64-bit cycle counter that is synchronized
> when the CPUs are brought on-line.  So for this case we don't need any
> fancy stuff.

Merged into the LTTng tree, with refactoring of the Octeon-specific
header file code into a new arch/mips/include/asm/octeon/trace-clock.h
file.

Thanks!

Mathieu

> 
> Signed-off-by: David Daney <ddaney@caviumnetworks.com>
> ---
>  arch/mips/Kconfig                   |    4 +-
>  arch/mips/include/asm/trace-clock.h |   39 
> ++++++++++++++++++++++++++++++++++-
>  arch/mips/kernel/smp.c              |    2 +
>  3 files changed, 42 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index a690e9b..9e91e8c 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -1782,8 +1782,8 @@ config HAVE_GET_CYCLES_32
>       def_bool y
>       depends on !CPU_R4400_WORKAROUNDS
>       select HAVE_TRACE_CLOCK
> -     select HAVE_TRACE_CLOCK_32_TO_64
> -     select HAVE_UNSYNCHRONIZED_TSC
> +     select HAVE_TRACE_CLOCK_32_TO_64 if (!CPU_CAVIUM_OCTEON)
> +     select HAVE_UNSYNCHRONIZED_TSC if (!CPU_CAVIUM_OCTEON)
>  
>  #
>  # Use the generic interrupt handling code in kernel/irq/:
> diff --git a/arch/mips/include/asm/trace-clock.h 
> b/arch/mips/include/asm/trace-clock.h
> index 3d8cb0f..a052f42 100644
> --- a/arch/mips/include/asm/trace-clock.h
> +++ b/arch/mips/include/asm/trace-clock.h
> @@ -12,6 +12,43 @@
>  
>  #define TRACE_CLOCK_MIN_PROBE_DURATION 200
>  
> +#ifdef CONFIG_CPU_CAVIUM_OCTEON
> +
> +#include <asm/octeon/octeon.h>
> +
> +#define TC_HW_BITS                   64
> +
> +static inline u32 trace_clock_read32(void)
> +{
> +     return (u32)read_c0_cvmcount(); /* only need the 32 LSB */
> +}
> +
> +static inline u64 trace_clock_read64(void)
> +{
> +     return read_c0_cvmcount();
> +}
> +
> +static inline u64 trace_clock_frequency(void)
> +{
> +     return octeon_get_clock_rate();
> +}
> +
> +static inline u32 trace_clock_freq_scale(void)
> +{
> +     return 1;
> +}
> +
> +static inline void get_trace_clock(void)
> +{
> +     return;
> +}
> +
> +static inline void put_trace_clock(void)
> +{
> +     return;
> +}
> +
> +#else /* !CONFIG_CPU_CAVIUM_OCTEON */
>  /*
>   * Number of hardware clock bits. The higher order bits are expected to be 0.
>   * If the hardware clock source has more than 32 bits, the bits higher than 
> the
> @@ -65,7 +102,7 @@ static inline void put_trace_clock(void)
>  {
>       put_synthetic_tsc();
>  }
> -
> +#endif /* CONFIG_CPU_CAVIUM_OCTEON */
>  static inline void set_trace_clock_is_sync(int state)
>  {
>  }
> diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
> index f8c50d1..42083eb 100644
> --- a/arch/mips/kernel/smp.c
> +++ b/arch/mips/kernel/smp.c
> @@ -159,7 +159,9 @@ void __init smp_cpus_done(unsigned int max_cpus)
>  {
>       mp_ops->cpus_done();
>       synchronise_count_master();
> +#ifdef CONFIG_HAVE_UNSYNCHRONIZED_TSC
>       test_tsc_synchronization();
> +#endif
>  }
>  
>  /* called from main before smp_init() */
> -- 
> 1.6.6.1
> 
> 
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> 

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com

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