Hi, I'm new to this list I'm using freshly-downloaded "stable" release, I'm just getting started so I may say some uninformed things. I'm on Xubuntu 14.04, x86-64, with 64GB RAM, of which I have reserved 24 GB for huge pages, intending to use it as a cache for a search in a game. Pages are accorningly 4KiB and 2MiB.
I'm a retired programmer with a special fondness for good documentation, willing to help write it. I have a little program I used to verify that I'm understanding things properly, attached. Its behavior deviates from the man pages. Specifically, a call to get_hugepage_region() that intentionally requests a region that is too large is being aborted in the library with a "warning" message. My beefs: - I don't expect warnings to abort - I really really don't like aborts from a library. It's the wrong place to make that decision. - the man page says it will return with NULL and something in errno. The message says it's from get_huge_pages, which I presume is an inner call, but that's also documented to return NULL. -- Kevin O'Gorman #define QUESTION ((bb) || (!bb)) /* Shakespeare */ Please consider the environment before printing this email.
/**
* @file
* <pre>Test of how to use a huge page mapping or a malloc (for time tests).
* You can watch the progress by using the command
* grep Huge /proc/meminfo</pre>
* Last Modified: Fri Dec 12 16:10:57 PST 2014
* @author Kevin O'Gorman
*/
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <hugetlbfs.h>
#define BUFL 1000
#define SIZE (32LLU*1024*1024*1024)
#define FLAGS (GHR_STRICT | GHR_COLOR)
int
main(int argc, char *argv[])
{
char *region;
char buf[BUFL];
size_t stride = sysconf(_SC_PAGESIZE);
int i;
if (argc > 1) {
region = (char *)malloc((size_t)SIZE);
} else {
region = (char *)get_hugepage_region((size_t)SIZE, GHR_DEFAULT);
}
if (!region) {
if (argc>1) {
/* malloc just about never fails on 64-bit processes. Doesn't mean you
* should do this.
*/
sprintf(buf, "Malloc of %lld bytes", (long long)SIZE);
} else {
/* The library actually doesn't even return in this case. */
sprintf(buf, "get_hugepage_region of %lld bytes", (long long)SIZE);
}
perror(buf);
exit(EXIT_FAILURE);
}
for (i = 0; i < SIZE; i+=stride) {
region[i] = 0;
}
return EXIT_SUCCESS;
}
Makefile
Description: Binary data
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