06-03-2002
Writing fast and efficiently - how ?
I have a lot of processes all of which need to write quite
a lot of data to the filesystem ( to a single file).
This is managed today in the following way : all the processes
write the data to a shared memory block, which is manged by a process that empties it to a file, thus allowing more space for
writing by the other processes.
It is now argued that this is slow and time- consuming,
specifically in times of high load on the shmem resource
(since each read/write is performed via a lock management
facility).
My question is : Will it be faster to dump the whole idea
of the shared memory and use the buffers that the O.S
provudes ? What type of locking will then be necessary ?
I am working on a AIX , RS6000 machine.
Thank you in advance for your comments !
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LEARN ABOUT CENTOS
mman.h
mman.h(3HEAD) Headers mman.h(3HEAD)
NAME
mman.h, mman - memory management declarations
SYNOPSIS
#include <sys/mman.h>
DESCRIPTION
The <sys/mman.h> header supports the following options:
o the Memory Mapped Files option
o the Shared Memory Objects option
o the Process Memory Locking option
o the Memory Protection option
o the Synchronized Input and Output option
For Memory Mapped Files and Shared Memory Objects options, the following protection options are defined:
PROT_READ Page can be read.
PROT_WRITE Page can be written.
PROT_EXEC Page can be executed.
PROT_NONE Page cannot be accessed.
The following flag options are defined:
MAP_SHARED Share changes.
MAP_PRIVATE Changes are private.
MAP_FIXED Interpret addr exactly.
The flags immediately following are defined for msync(). See msync(3C).
MS_ASYNC Perform asynchronous writes.
MS_SYNC Perform synchronous writes.
MS_INVALIDATE Invalidate mappings.
The symbolic constants immediately following are defined for the mlockall() function. See mlockall(3C).
MCL_CURRENT Lock currently mapped pages.
MCL_FUTURE Lock pages that become mapped.
The symbolic constant MAP_FAILED is defined to indicate a failure from the mmap() function. See mmap(2).
The mode_t, off_t, and size_t types are be defined as described in <sys/types.h>. See types(3HEAD).
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Interface Stability |Standard |
+-----------------------------+-----------------------------+
SEE ALSO
mmap(2), mprotect(2), munmap(2), madvise(3C), mlock(3C), mlockall(3C), msync(3C), shm_open(3RT), shm_unlink(3RT), attributes(5), stan-
dards(5)
SunOS 5.10 10 Sep 2004 mman.h(3HEAD)