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allocate lazy memory to use only required amount

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This commit is contained in:
Alexander Zubkov
2021-12-01 19:22:12 +01:00
parent 12e2dc2d1e
commit d860bc330c
2 changed files with 62 additions and 36 deletions
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46
plageq.c
View File

@@ -1,5 +1,5 @@
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <string.h>
#include <error.h>
#include <errno.h>
@@ -17,8 +17,6 @@ struct node {
typedef struct node *iptree;
typedef void (*bitsfun)(bits, mask_t, mask_t, mask_t);
pos_t maxpos = 0;
void clearb(uint8_t *b) {
bzero(b, DEPTHB);
}
@@ -41,24 +39,37 @@ int getb(uint8_t *b, int n) {
}
iptree iptree_new(pos_t size) {
iptree t = malloc(size * sizeof(struct node));
if (t == 0) error(1, errno, "iptree_new: malloc failed");
pos_t i;
for(i = 0; i < size; ++i) {
t[i].a[0] = i + 1;
t[i].a[1] = 0;
clearb(t[i].b);
}
t[i].a[0] = 0;
// use mmap to get pages lazily and zeroed
iptree t = mmap(0, size * sizeof(struct node), PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
if (t == MAP_FAILED) error(1, errno, "iptree_new: mmap failed");
// use 2 queues of free nodes
t[0].a[0] = 1; // start of continuous range
t[0].a[1] = 0; // pointer to a chain of free nodes
t[size - 1].a[0] = 1; // end of countinous range marker
return t;
}
pos_t iptree_popfree(iptree t) {
pos_t f = t[0].a[0];
if (f > maxpos) maxpos = f;
if (!f) error(1, 0, "iptree_popfree: no free nodes left");
t[0].a[0] = t[f].a[0];
t[f].a[0] = 0;
pos_t f;
if (t[0].a[1]) {
// try from chain first
f = t[0].a[1];
t[0].a[1] = t[f].a[0]; // shift pointer to the next node
t[f].a[0] = 0; // clear popped element
} else if (t[0].a[0]) {
// then try if something is left in continuous range
f = t[0].a[0]; // start of the range
if (t[f].a[0]) {
// this is the last element
t[0].a[0] = 0;
t[f].a[0] = 0; // celar popped element
} else {
// more elements are there in the range
++(t[0].a[0]);
}
} else {
if (!f) error(1, 0, "iptree_popfree: no free nodes left");
}
return f;
}
@@ -211,6 +222,7 @@ int main(void) {
iptree_traverse(t, ip4, print4);
iptree_traverse(t, ip6, print6);
pos_t maxpos = t[0].a[0] ? t[0].a[0] : SIZE;
double mb_used = nodes2mb(maxpos);
double mb_all = nodes2mb(SIZE);
fprintf(stderr, "max nodes: %.2f%%, %d / %d, %.2fMB / %.2fMB\n", maxpos / (double)SIZE * 100.0, maxpos, SIZE, mb_used, mb_all);

52
plagmax.c
View File

@@ -1,5 +1,5 @@
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <string.h>
#include <error.h>
#include <errno.h>
@@ -11,33 +11,46 @@ struct node { pos_t a[2]; };
typedef struct node *iptree;
typedef void (*bitsfun)(bits, mask_t);
pos_t maxpos = 0;
iptree iptree_new(pos_t size) {
iptree t = malloc(size * sizeof(struct node));
if (t == 0) error(1, errno, "iptree_new: malloc failed");
pos_t i;
for(i = 0; i < size; ++i) {
t[i].a[0] = i + 1;
t[i].a[1] = 0;
}
t[i].a[0] = 0;
// use mmap to get pages lazily and zeroed
iptree t = mmap(0, size * sizeof(struct node), PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
if (t == MAP_FAILED) error(1, errno, "iptree_new: mmap failed");
// use 2 queues of free nodes
t[0].a[0] = 1; // start of continuous range
t[0].a[1] = 0; // pointer to a chain of free nodes
t[size - 1].a[0] = 1; // end of countinous range marker
return t;
}
pos_t iptree_popfree(iptree t) {
pos_t f = t[0].a[0];
if (f > maxpos) maxpos = f;
if (!f) error(1, 0, "iptree_popfree: no free nodes left");
t[0].a[0] = t[f].a[0];
t[f].a[0] = 0;
pos_t f;
if (t[0].a[1]) {
// try from chain first
f = t[0].a[1];
t[0].a[1] = t[f].a[0]; // shift pointer to the next node
t[f].a[0] = 0; // clear popped element
} else if (t[0].a[0]) {
// then try if something is left in continuous range
f = t[0].a[0]; // start of the range
if (t[f].a[0]) {
// this is the last element
t[0].a[0] = 0;
t[f].a[0] = 0; // celar popped element
} else {
// more elements are there in the range
++(t[0].a[0]);
}
} else {
error(1, 0, "iptree_popfree: no free nodes left");
}
return f;
}
void iptree_pushfree(iptree t, pos_t f) {
t[f].a[0] = t[0].a[0];
t[f].a[1] = 0;
t[0].a[0] = f;
// elements are pushed only to the pointer chain
t[f].a[0] = t[0].a[1]; // pointer to current head
t[f].a[1] = 0; // clear remaining fields
t[0].a[1] = f; // redirect the pointer to new head
}
int iptree_is_term(iptree t, pos_t h) {
@@ -191,6 +204,7 @@ int main(void) {
iptree_traverse(t, ip4, print4);
iptree_traverse(t, ip6, print6);
pos_t maxpos = t[0].a[0] ? t[0].a[0] : SIZE;
double mb_used = nodes2mb(maxpos);
double mb_all = nodes2mb(SIZE);
fprintf(stderr, "max nodes: %.2f%%, %d / %d, %.2fMB / %.2fMB\n", maxpos / (double)SIZE * 100.0, maxpos, SIZE, mb_used, mb_all);