[lttng-dev] [PATCH 1/2] Add default subbuf sizes getter functions

[David Goulet]

Yes +1 for the inline so I'll let you resubmit and fix the dot on the
last patch.

Thanks!
David

Simon Marchi:
> This patch adds src/common/defaults.c file. It contains functions to
> retrieve defaults subbuf sizes. It uses the DEFAULT_*_SUBBUF_SIZE
> defines from defaults.h but also make sure that the values are at least
> as big as the page size.
> 
> Signed-off-by: Simon Marchi <simon.marchi at polymtl.ca>
> ---
>  src/common/Makefile.am |    2 +-
>  src/common/defaults.c  |   91 ++++++++++++++++++++++++++++++++++++++++++++++++
>  src/common/defaults.h  |    7 ++++
>  3 files changed, 99 insertions(+), 1 deletions(-)
>  create mode 100644 src/common/defaults.c
> 
> diff --git a/src/common/Makefile.am b/src/common/Makefile.am
> index b43b376..f91259c 100644
> --- a/src/common/Makefile.am
> +++ b/src/common/Makefile.am
> @@ -12,7 +12,7 @@ noinst_HEADERS = lttng-kernel.h defaults.h macros.h error.h futex.h \
>  noinst_LTLIBRARIES = libcommon.la
>  
>  libcommon_la_SOURCES = error.h error.c utils.c utils.h runas.c runas.h \
> -                       common.h futex.c futex.h uri.c uri.h
> +                       common.h futex.c futex.h uri.c uri.h defaults.c
>  
>  # Consumer library
>  noinst_LTLIBRARIES += libconsumer.la
> diff --git a/src/common/defaults.c b/src/common/defaults.c
> new file mode 100644
> index 0000000..cde4fb9
> --- /dev/null
> +++ b/src/common/defaults.c
> @@ -0,0 +1,91 @@
> +/*
> + * Copyright (C) 2012 - Simon Marchi <simon.marchi at polymtl.ca>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License, version 2 only,
> + * as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along
> + * with this program; if not, write to the Free Software Foundation, Inc.,
> + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
> + */
> +
> +#include <stddef.h>
> +#include <unistd.h>
> +
> +#include "defaults.h"
> +
> +#ifndef max
> +#define max(a, b) ((a) > (b) ? (a) : (b))
> +#endif
> +
> +static size_t default_channel_subbuf_size;
> +static size_t default_metadata_subbuf_size;
> +static size_t default_kernel_channel_subbuf_size;
> +static size_t default_ust_channel_subbuf_size;
> +
> +static void __attribute__((constructor)) init_defaults(void)
> +{
> +	/* libringbuffer won't accept subbuf sizes smaller than the page size,
> +	 * so. If the default subbuf size is smaller, replace it by the page
> +	 * size. */
> +	long page_size = sysconf(_SC_PAGESIZE);
> +	
> +	if (page_size < 0) {
> +		page_size = 0;
> +	}
> +
> +	default_channel_subbuf_size = max(DEFAULT_CHANNEL_SUBBUF_SIZE, page_size);
> +	default_metadata_subbuf_size = max(DEFAULT_METADATA_SUBBUF_SIZE, page_size);
> +	default_kernel_channel_subbuf_size = max(DEFAULT_KERNEL_CHANNEL_SUBBUF_SIZE, page_size);
> +	default_ust_channel_subbuf_size = max(DEFAULT_UST_CHANNEL_SUBBUF_SIZE, page_size);
> +}
> +
> +/*
> + * Returns the default subbuf size.
> + *
> + * This function depends on a value that is set at constructor time, so it is
> + * unsafe to call it from another constructor.
> + */
> +size_t default_get_channel_subbuf_size(void)
> +{
> +	return default_channel_subbuf_size;
> +}
> +
> +/*
> + * Returns the default metadata subbuf size.
> + *
> + * This function depends on a value that is set at constructor time, so it is
> + * unsafe to call it from another constructor.
> + */
> +size_t default_get_metadata_subbuf_size(void)
> +{
> +	return default_metadata_subbuf_size;
> +}
> +
> +/*
> + * Returns the default subbuf size for the kernel domain.
> + *
> + * This function depends on a value that is set at constructor time, so it is
> + * unsafe to call it from another constructor.
> + */
> +size_t default_get_kernel_channel_subbuf_size(void)
> +{
> +	return default_kernel_channel_subbuf_size;
> +}
> +
> +/*
> + * Returns the default subbuf size for the UST domain.
> + *
> + * This function depends on a value that is set at constructor time, so it is
> + * unsafe to call it from another constructor.
> + */
> +size_t default_get_ust_channel_subbuf_size(void)
> +{
> +	return default_ust_channel_subbuf_size;
> +}
> diff --git a/src/common/defaults.h b/src/common/defaults.h
> index 0c0b6ac..94a54c1 100644
> --- a/src/common/defaults.h
> +++ b/src/common/defaults.h
> @@ -109,6 +109,9 @@
>  #define DEFAULT_METADATA_SUBBUF_SIZE    4096
>  #define DEFAULT_METADATA_SUBBUF_NUM     2
>  
> +size_t default_get_channel_subbuf_size(void);
> +size_t default_get_metadata_subbuf_size(void);
> +
>  /* Kernel has different defaults */
>  
>  /* DEFAULT_KERNEL_CHANNEL_SUBBUF_SIZE must always be a power of 2 */
> @@ -121,6 +124,8 @@
>  /* See lttng-kernel.h enum lttng_kernel_output for channel output */
>  #define DEFAULT_KERNEL_CHANNEL_OUTPUT       LTTNG_EVENT_SPLICE
>  
> +size_t default_get_kernel_channel_subbuf_size(void);
> +
>  /* User space defaults */
>  
>  /* Must be a power of 2 */
> @@ -130,6 +135,8 @@
>  /* See lttng-ust.h enum lttng_ust_output */
>  #define DEFAULT_UST_CHANNEL_OUTPUT          LTTNG_EVENT_MMAP
>  
> +size_t default_get_ust_channel_subbuf_size(void);
> +
>  /*
>   * Default timeout value for the sem_timedwait() call. Blocking forever is not
>   * wanted so a timeout is used to control the data flow and not freeze the