[lttng-dev] [PATCH 1/3] Add default subbuf sizes getter functions.
Mathieu Desnoyers
mathieu.desnoyers at efficios.com
Fri Nov 9 10:54:39 EST 2012
* David Goulet (dgoulet at efficios.com) wrote:
> Hi Simon,
>
> Can you please rename the get_default_* function family to default_get_*
> in order to respect the name spacing of files.
Also, Simon, please remove the "dot" at the end of the Title line of
your patch.
Thanks,
Mathieu
>
> Comment below:
>
> Simon Marchi:
> > This patch adds src/common/defaults.c file. It contains functions to
> > retrieve defaults subbuf sizes based on the architecture page size.
> >
> > Signed-off-by: Simon Marchi <simon.marchi at polymtl.ca>
> > ---
> > src/common/Makefile.am | 2 +-
> > src/common/defaults.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++++
> > src/common/defaults.h | 7 ++++
> > 3 files changed, 94 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..48d6605
> > --- /dev/null
> > +++ b/src/common/defaults.c
> > @@ -0,0 +1,86 @@
> > +/*
> > + * 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"
> > +
> > +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)
> > +{
> > + default_kernel_channel_subbuf_size = DEFAULT_KERNEL_CHANNEL_SUBBUF_SIZE;
>
> Why is the kernel getting a default value and not a page size ?
>
> > +
> > + long page_size = sysconf(_SC_PAGESIZE);
> > + if (page_size > 0) {
> > + default_channel_subbuf_size = page_size;
> > + default_metadata_subbuf_size = page_size;
> > + default_ust_channel_subbuf_size = page_size;
> > + } else {
> > + default_channel_subbuf_size = 4096;
> > + default_metadata_subbuf_size = 4096;
> > + default_ust_channel_subbuf_size = 4096;
>
> Should we use a default value for this 4096 size here with a
> DEFINE_*_SUBBUF_SIZE or... ?
>
> Seems a bit odd that the kernel got a default define value but not UST
> and metadata.
>
> > + }
> > +}
> > +
> > +/*
> > + * 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 get_default_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 get_default_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 get_default_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 get_default_ust_channel_subbuf_size(void)
> > +{
> > + return default_ust_channel_subbuf_size;
> > +}
>
> I'm wondering if all these functions should be static inline in the
> default.h...
>
> Thoughts?
>
> Otherwise, the patch looks good!
>
> Thanks
> David
>
> > diff --git a/src/common/defaults.h b/src/common/defaults.h
> > index 0c0b6ac..efff43e 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 get_default_channel_subbuf_size(void);
> > +size_t get_default_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 get_default_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 get_default_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
>
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--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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