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page-info.h
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page-info.h
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/*
* page-info.h
*/
#ifndef PAGE_INFO_H_
#define PAGE_INFO_H_
#include <stddef.h>
#include <inttypes.h>
#include <stdbool.h>
#include <stdio.h>
#ifdef __cplusplus
extern "C" {
#endif
typedef struct {
/* page frame number: if present, the physical frame for the page */
uint64_t pfn;
/* soft-dirty set */
bool softdirty;
/* exclusively mapped, see e.g., https://patchwork.kernel.org/patch/6787921/ */
bool exclusive;
/* is a file mapping */
bool file;
/* page is swapped out */
bool swapped;
/* page is present, i.e, a physical page is allocated */
bool present;
/* if true, the kpageflags were successfully loaded, if false they were not (and are all zero) */
bool kpageflags_ok;
/* the 64-bit flag value extracted from /proc/kpageflags only if pfn is non-null */
uint64_t kpageflags;
} page_info;
/*
* Information for a number of virtually consecutive pages.
*/
typedef struct {
/* how many page_info structures are in the array pointed to by info */
size_t num_pages;
/* pointer to the array of page_info structures */
page_info *info;
} page_info_array;
typedef struct {
/* the number of pages on which this flag was set, always <= pages_available */
size_t pages_set;
/* the number of pages on which information could be obtained */
size_t pages_available;
/* the total number of pages examined, which may be greater than pages_available if
* the flag value could not be obtained for some pages (usually because the pfn is not available
* since the page is not yet present or because running as non-root.
*/
size_t pages_total;
/* the flag the values were queried for */
int flag;
} flag_count;
/**
* Examine the page info in infos to count the number of times a specified /proc/kpageflags flag was set,
* effectively giving you a ratio, so you can say "80% of the pages for this allocation are backed by
* huge pages" or whatever.
*
* The flags *must* come from kpageflags (these are not the same as those in /proc/pid/pagemap) and
* are declared in linux/kernel-page-flags.h.
*
* Ideally, the flag information is available for all the pages in the range, so you can
* say something about the entire range, but this is often not the case because (a) flags
* are not available for pages that aren't present and (b) flags are generally never available
* for non-root users. So the ratio structure indicates both the total number of pages as
* well as the number of pages for which the flag information was available.
*/
flag_count get_flag_count(page_info_array infos, int flag);
/**
* Given the case-insensitive name of a flag, return the flag number (the index of the bit
* representing this flag), or -1 if the flag is not found. The "names" of the flags are
* the same as the macro names in <linux/kernel-page-flags.h> without the KPF_ prefix.
*
* For example, the name of the transparent hugepages flag is "THP" and the corresponding
* macro is KPF_THP, and the value of this macro and returned by this method is 22.
*
* You can generate the corresponding mask value to check the flag using (1ULL << value).
*/
int flag_from_name(char const *name);
/**
* Print the info in the page_info structure to stdout.
*/
void print_info(page_info info);
/**
* Print the info in the page_info structure to the give file.
*/
void fprint_info(FILE* file, page_info info);
/**
* Print the table header that lines up with the tabluar format used by the "table" printing
* functions. Called by fprint_ratios, or you can call it yourself if you want to prefix the
* output with your own columns.
*/
void fprint_info_header(FILE *file);
/* print one info in a tabular format (as a single row) */
void fprint_info_row(FILE *file, page_info info);
/**
* Print the ratio for each flag in infos. The ratio is the number of times the flag was set over
* the total number of pages (or the total number of pages for which the information could be obtained).
*/
void fprint_ratios_noheader(FILE *file, page_info_array infos);
/*
* Print a table with one row per page from the given infos.
*/
void fprint_ratios(FILE *file, page_info_array infos);
/*
* Prints a summary of all the pages in the given array as ratios: the fraction of the time the given
* flag was set.
*/
void fprint_table(FILE *f, page_info_array infos);
/**
* Get info for a single page indicated by the given pointer (which may point anywhere in the page).
*/
page_info get_page_info(void *p);
/**
* Get information for each page in the range from start (inclusive) to end (exclusive).
*/
page_info_array get_info_for_range(void *start, void *end);
/**
* Free the memory associated with the given page_info_array. You shouldn't use it after this call.
*/
void free_info_array(page_info_array infos);
#ifdef __cplusplus
}
#endif
#endif /* PAGE_INFO_H_ */