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// SPDX-License-Identifier: GPL-3.0-or-later
#include "ebpf.h"
#include "ebpf_cachestat.h"
static ebpf_data_t cachestat_data;
netdata_publish_cachestat_t **cachestat_pid;
static struct bpf_link **probe_links = NULL;
static struct bpf_object *objects = NULL;
static char *cachestat_counter_dimension_name[NETDATA_CACHESTAT_END] = { "ratio", "dirty", "hit",
"miss" };
static netdata_syscall_stat_t *cachestat_counter_aggregated_data = NULL;
static netdata_publish_syscall_t *cachestat_counter_publish_aggregated = NULL;
netdata_cachestat_pid_t *cachestat_vector = NULL;
static netdata_idx_t *cachestat_hash_values = NULL;
static int read_thread_closed = 1;
struct netdata_static_thread cachestat_threads = {"CACHESTAT KERNEL",
NULL, NULL, 1, NULL,
NULL, NULL};
static int *map_fd = NULL;
/*****************************************************************
*
* FUNCTIONS TO CLOSE THE THREAD
*
*****************************************************************/
/**
* Clean PID structures
*
* Clean the allocated structures.
*/
static void clean_pid_structures() {
struct pid_stat *pids = root_of_pids;
while (pids) {
freez(cachestat_pid[pids->pid]);
pids = pids->next;
}
}
/**
* Clean up the main thread.
*
* @param ptr thread data.
*/
static void ebpf_cachestat_cleanup(void *ptr)
{
ebpf_module_t *em = (ebpf_module_t *)ptr;
if (!em->enabled)
return;
heartbeat_t hb;
heartbeat_init(&hb);
uint32_t tick = 2*USEC_PER_MS;
while (!read_thread_closed) {
usec_t dt = heartbeat_next(&hb, tick);
UNUSED(dt);
}
clean_pid_structures();
freez(cachestat_pid);
freez(cachestat_counter_aggregated_data);
ebpf_cleanup_publish_syscall(cachestat_counter_publish_aggregated);
freez(cachestat_counter_publish_aggregated);
freez(cachestat_vector);
freez(cachestat_hash_values);
struct bpf_program *prog;
size_t i = 0 ;
bpf_object__for_each_program(prog, objects) {
bpf_link__destroy(probe_links[i]);
i++;
}
bpf_object__close(objects);
}
/*****************************************************************
*
* COMMON FUNCTIONS
*
*****************************************************************/
/**
* Write charts
*
* Write the current information to publish the charts.
*
* @param family chart family
* @param chart chart id
* @param dim dimension name
* @param v1 value.
*/
static inline void cachestat_write_charts(char *family, char *chart, char *dim, long long v1)
{
write_begin_chart(family, chart);
write_chart_dimension(dim, v1);
write_end_chart();
}
/**
* Update publish
*
* Update publish values before to write dimension.
*
* @param out strcuture that will receive data.
* @param mpa calls for mark_page_accessed during the last second.
* @param mbd calls for mark_buffer_dirty during the last second.
* @param apcl calls for add_to_page_cache_lru during the last second.
* @param apd calls for account_page_dirtied during the last second.
*/
void cachestat_update_publish(netdata_publish_cachestat_t *out, uint64_t mpa, uint64_t mbd,
uint64_t apcl, uint64_t apd)
{
// Adapted algorithm from https://github.com/iovisor/bcc/blob/master/tools/cachestat.py#L126-L138
calculated_number total = (calculated_number) (((long long)mpa) - ((long long)mbd));
if (total < 0)
total = 0;
calculated_number misses = (calculated_number) ( ((long long) apcl) - ((long long) apd) );
if (misses < 0)
misses = 0;
// If hits are < 0, then its possible misses are overestimate due to possibly page cache read ahead adding
// more pages than needed. In this case just assume misses as total and reset hits.
calculated_number hits = total - misses;
if (hits < 0 ) {
misses = total;
hits = 0;
}
calculated_number ratio = (total > 0) ? hits/total : 0;
out->ratio = (long long )(ratio*100);
out->hit = (long long)hits;
out->miss = (long long)misses;
}
/**
* Save previous values
*
* Save values used this time.
*
* @param publish
*/
static void save_previous_values(netdata_publish_cachestat_t *publish) {
publish->prev.mark_page_accessed = cachestat_hash_values[NETDATA_KEY_CALLS_MARK_PAGE_ACCESSED];
publish->prev.account_page_dirtied = cachestat_hash_values[NETDATA_KEY_CALLS_ACCOUNT_PAGE_DIRTIED];
publish->prev.add_to_page_cache_lru = cachestat_hash_values[NETDATA_KEY_CALLS_ADD_TO_PAGE_CACHE_LRU];
publish->prev.mark_buffer_dirty = cachestat_hash_values[NETDATA_KEY_CALLS_MARK_BUFFER_DIRTY];
}
/**
* Calculate statistics
*
* @param publish the structure where we will store the data.
*/
static void calculate_stats(netdata_publish_cachestat_t *publish) {
if (!publish->prev.mark_page_accessed) {
save_previous_values(publish);
return;
}
uint64_t mpa = cachestat_hash_values[NETDATA_KEY_CALLS_MARK_PAGE_ACCESSED] - publish->prev.mark_page_accessed;
uint64_t mbd = cachestat_hash_values[NETDATA_KEY_CALLS_MARK_BUFFER_DIRTY] - publish->prev.mark_buffer_dirty;
uint64_t apcl = cachestat_hash_values[NETDATA_KEY_CALLS_ADD_TO_PAGE_CACHE_LRU] - publish->prev.add_to_page_cache_lru;
uint64_t apd = cachestat_hash_values[NETDATA_KEY_CALLS_ACCOUNT_PAGE_DIRTIED] - publish->prev.account_page_dirtied;
save_previous_values(publish);
// We are changing the original algorithm to have a smooth ratio.
cachestat_update_publish(publish, mpa, mbd, apcl, apd);
}
/*****************************************************************
*
* APPS
*
*****************************************************************/
/**
* Apps Accumulator
*
* Sum all values read from kernel and store in the first address.
*
* @param out the vector with read values.
*/
static void cachestat_apps_accumulator(netdata_cachestat_pid_t *out)
{
int i, end = (running_on_kernel >= NETDATA_KERNEL_V4_15) ? ebpf_nprocs : 1;
netdata_cachestat_pid_t *total = &out[0];
for (i = 1; i < end; i++) {
netdata_cachestat_pid_t *w = &out[i];
total->account_page_dirtied += w->account_page_dirtied;
total->add_to_page_cache_lru += w->add_to_page_cache_lru;
total
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