MEMINFO(2) System Calls MEMINFO(2)


NAME


meminfo - provide information about memory

SYNOPSIS


#include <sys/types.h>
#include <sys/mman.h>

int meminfo(const uint64_t inaddr[], int addr_count,
const uint_t info_req[], int info_count, uint64_t outdata[],
uint_t validity[]);


PARAMETERS


inaddr
array of input addresses; the maximum number of addresses
that can be processed for each call is MAX_MEMINFO_CNT


addr_count
number of addresses


info_req
array of types of information requested


info_count
number of pieces of information requested for each address
in inaddr


outdata
array into which results are placed; array size must be the
product of info_count and addr_count


validity
array of size addr_count containing bitwise result codes;
0th bit evaluates validity of corresponding input address,
1st bit validity of response to first member of info_req,
and so on


DESCRIPTION


The meminfo() function provides information about virtual and physical
memory particular to the calling process. The user or developer of
performance utilities can use this information to analyze system memory
allocations and develop a better understanding of the factors affecting
application performance.


The caller of meminfo() can obtain the following types of information
about both virtual and physical memory.

MEMINFO_VPHYSICAL
physical address corresponding to virtual
address


MEMINFO_VLGRP
locality group of physical page corresponding
to virtual address


MEMINFO_VPAGESIZE
size of physical page corresponding to virtual
address


MEMINFO_VREPLCNT
number of replicated physical pages
corresponding to specified virtual address


MEMINFO_VREPL | n
nth physical replica of specified virtual
address


MEMINFO_VREPL_LGRP | n
lgrp of nth physical replica of specified
virtual address


MEMINFO_PLGRP
locality group of specified physical address


All but MEMINFO_VLGRP and MEMINFO_VPAGESIZE require the PRIV_PROC_MEMINFO
privilege.


RETURN VALUES


Upon successful completion meminfo() returns 0. Otherwise -1 is returned
and errno is set to indicate the error.

ERRORS


The meminfo() function will fail if:

EFAULT
The area pointed to by outdata or validity could not be
written, or the data pointed to by info_req or inaddr could not
be read.


EINVAL
The value of info_count is greater than 31 or less than 1, or
the value of addr_count is less than 1.


EXAMPLES


Example 1: Print physical pages and page sizes corresponding to a set of


virtual addresses.


The following example prints the physical pages and page sizes
corresponding to a set of virtual addresses.


void
print_info(void **addrvec, int how_many)
{
static const uint_t info[] = {
MEMINFO_VPHYSICAL,
MEMINFO_VPAGESIZE
};

int info_num = sizeof (info) / sizeof (info[0]);
int i;

uint64_t *inaddr = alloca(sizeof (uint64_t) * how_many);
uint64_t *outdata = alloca(sizeof (uint64_t) * how_many * info_num);
uint_t *validity = alloca(sizeof (uint_t) * how_many);

for (i = 0; i < how_many; i++)
inaddr[i] = (uint64_t)addrvec[i];

if (meminfo(inaddr, how_many, info, info_num, outdata,
validity) < 0) {
perror("meminfo");
return;
}

for (i = 0; i < how_many; i++) {
if ((validity[i] & 1) == 0)
printf("address 0x%llx not part of address space\n",
inaddr[i]);

else if ((validity[i] & 2) == 0)
printf("address 0x%llx has no physical page "
"associated with it\n", inaddr[i]);

else {
char buff[80];
if ((validity[i] & 4) == 0)
strcpy(buff, "<Unknown>");
else
sprintf(buff, "%lld",
outdata[i * info_num + 1]);

printf("address 0x%llx is backed by physical "
"page 0x%llx of size %s\n",
inaddr[i], outdata[i * info_num], buff);
}
}
}


ATTRIBUTES


See attributes(5) for descriptions of the following attributes:


+--------------------+-------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------+
|Interface Stability | Stable |
+--------------------+-------------------+
|MT-Level | Async-Signal-Safe |
+--------------------+-------------------+

SEE ALSO


memcntl(2), mmap(2), gethomelgroup(3C), getpagesize(3C), madvise(3C),
sysconf(3C), attributes(5), privileges(5)


March 10, 2015 MEMINFO(2)