try_context() is such a hot path that the hashmap lookup is expensive.
The number of contexts is small - it is the number of object types.
Using a hashmap is overkill. A plain array will do.
Before:
$ time ./journalctl --since=2014-06-01 --until=2014-07-01 > /dev/null
real 0m9.445s
user 0m9.228s
sys 0m0.213s
After:
$ time ./journalctl --since=2014-06-01 --until=2014-07-01 > /dev/null
real 0m5.438s
user 0m5.266s
sys 0m0.170s
static unsigned type_to_context(ObjectType type) {
/* One context for each type, plus one catch-all for the rest */
static unsigned type_to_context(ObjectType type) {
/* One context for each type, plus one catch-all for the rest */
+ assert_cc(_OBJECT_TYPE_MAX <= MMAP_CACHE_MAX_CONTEXTS);
return type > OBJECT_UNUSED && type < _OBJECT_TYPE_MAX ? type : 0;
}
return type > OBJECT_UNUSED && type < _OBJECT_TYPE_MAX ? type : 0;
}
+ Context *contexts[MMAP_CACHE_MAX_CONTEXTS];
LIST_HEAD(Window, unused);
Window *last_unused;
LIST_HEAD(Window, unused);
Window *last_unused;
static Context *context_add(MMapCache *m, unsigned id) {
Context *c;
static Context *context_add(MMapCache *m, unsigned id) {
Context *c;
- c = hashmap_get(m->contexts, UINT_TO_PTR(id + 1));
- r = hashmap_ensure_allocated(&m->contexts, NULL);
- if (r < 0)
- return NULL;
-
c = new0(Context, 1);
if (!c)
return NULL;
c = new0(Context, 1);
if (!c)
return NULL;
c->cache = m;
c->id = id;
c->cache = m;
c->id = id;
- r = hashmap_put(m->contexts, UINT_TO_PTR(id + 1), c);
- if (r < 0) {
- free(c);
- return NULL;
- }
+ assert(!m->contexts[id]);
+ m->contexts[id] = c;
context_detach_window(c);
context_detach_window(c);
- if (c->cache)
- assert_se(hashmap_remove(c->cache->contexts, UINT_TO_PTR(c->id + 1)));
+ if (c->cache) {
+ assert(c->cache->contexts[c->id] == c);
+ c->cache->contexts[c->id] = NULL;
+ }
}
static void mmap_cache_free(MMapCache *m) {
}
static void mmap_cache_free(MMapCache *m) {
- while ((c = hashmap_first(m->contexts)))
- context_free(c);
-
- hashmap_free(m->contexts);
+ for (i = 0; i < MMAP_CACHE_MAX_CONTEXTS; i++)
+ if (m->contexts[i])
+ context_free(m->contexts[i]);
while ((f = hashmap_first(m->fds)))
fd_free(f);
while ((f = hashmap_first(m->fds)))
fd_free(f);
assert(size > 0);
assert(ret);
assert(size > 0);
assert(ret);
- c = hashmap_get(m->contexts, UINT_TO_PTR(context+1));
+ c = m->contexts[context];
assert(fd >= 0);
assert(size > 0);
assert(ret);
assert(fd >= 0);
assert(size > 0);
assert(ret);
+ assert(context < MMAP_CACHE_MAX_CONTEXTS);
/* Check whether the current context is the right one already */
r = try_context(m, fd, prot, context, keep_always, offset, size, ret);
/* Check whether the current context is the right one already */
r = try_context(m, fd, prot, context, keep_always, offset, size, ret);
#include <stdbool.h>
#include <sys/stat.h>
#include <stdbool.h>
#include <sys/stat.h>
+#define MMAP_CACHE_MAX_CONTEXTS 8
+
typedef struct MMapCache MMapCache;
MMapCache* mmap_cache_new(void);
typedef struct MMapCache MMapCache;
MMapCache* mmap_cache_new(void);