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authorEric Dumazet <eric.dumazet@gmail.com>2010-11-09 18:29:27 +0300
committerMichal Marek <mmarek@suse.cz>2010-11-11 19:12:06 +0300
commit8af27e1dc4e4dd7a7b04c2cd0fc3d419d91d45b0 (patch)
tree0cf6febb82aafa421259a69007a6e848c3b9fa3c /scripts/basic
parentd63f6d1b4d3ad0d88685a5f8eb1c3cac01ddd0db (diff)
downloadlinux-8af27e1dc4e4dd7a7b04c2cd0fc3d419d91d45b0.tar.xz
fixdep: use hash table instead of a single array
I noticed fixdep uses ~2% of cpu time in kernel build, in function use_config() fixdep spends a lot of cpu cycles in linear searches in its internal string array. With about 400 stored strings per dep file, this begins to be noticeable. Convert fixdep to use a hash table. kbuild results on my x86_64 allmodconfig Before patch : real 10m30.414s user 61m51.456s sys 8m28.200s real 10m12.334s user 61m50.236s sys 8m30.448s real 10m42.947s user 61m50.028s sys 8m32.380s After: real 10m8.180s user 61m22.506s sys 8m32.384s real 10m35.039s user 61m21.654s sys 8m32.212s real 10m14.487s user 61m23.498s sys 8m32.312s Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Michal Marek <mmarek@suse.cz>
Diffstat (limited to 'scripts/basic')
-rw-r--r--scripts/basic/fixdep.c109
1 files changed, 61 insertions, 48 deletions
diff --git a/scripts/basic/fixdep.c b/scripts/basic/fixdep.c
index ea26b23de082..ed0584623690 100644
--- a/scripts/basic/fixdep.c
+++ b/scripts/basic/fixdep.c
@@ -138,38 +138,36 @@ static void print_cmdline(void)
printf("cmd_%s := %s\n\n", target, cmdline);
}
-char * str_config = NULL;
-int size_config = 0;
-int len_config = 0;
+struct item {
+ struct item *next;
+ unsigned int len;
+ unsigned int hash;
+ char name[0];
+};
-/*
- * Grow the configuration string to a desired length.
- * Usually the first growth is plenty.
- */
-static void grow_config(int len)
-{
- while (len_config + len > size_config) {
- if (size_config == 0)
- size_config = 2048;
- str_config = realloc(str_config, size_config *= 2);
- if (str_config == NULL)
- { perror("fixdep:malloc"); exit(1); }
- }
-}
+#define HASHSZ 256
+static struct item *hashtab[HASHSZ];
+static unsigned int strhash(const char *str, unsigned int sz)
+{
+ /* fnv32 hash */
+ unsigned int i, hash = 2166136261U;
+ for (i = 0; i < sz; i++)
+ hash = (hash ^ str[i]) * 0x01000193;
+ return hash;
+}
/*
* Lookup a value in the configuration string.
*/
-static int is_defined_config(const char * name, int len)
+static int is_defined_config(const char *name, int len, unsigned int hash)
{
- const char * pconfig;
- const char * plast = str_config + len_config - len;
- for ( pconfig = str_config + 1; pconfig < plast; pconfig++ ) {
- if (pconfig[ -1] == '\n'
- && pconfig[len] == '\n'
- && !memcmp(pconfig, name, len))
+ struct item *aux;
+
+ for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) {
+ if (aux->hash == hash && aux->len == len &&
+ memcmp(aux->name, name, len) == 0)
return 1;
}
return 0;
@@ -178,13 +176,19 @@ static int is_defined_config(const char * name, int len)
/*
* Add a new value to the configuration string.
*/
-static void define_config(const char * name, int len)
+static void define_config(const char *name, int len, unsigned int hash)
{
- grow_config(len + 1);
+ struct item *aux = malloc(sizeof(*aux) + len);
- memcpy(str_config+len_config, name, len);
- len_config += len;
- str_config[len_config++] = '\n';
+ if (!aux) {
+ perror("fixdep:malloc");
+ exit(1);
+ }
+ memcpy(aux->name, name, len);
+ aux->len = len;
+ aux->hash = hash;
+ aux->next = hashtab[hash % HASHSZ];
+ hashtab[hash % HASHSZ] = aux;
}
/*
@@ -192,40 +196,49 @@ static void define_config(const char * name, int len)
*/
static void clear_config(void)
{
- len_config = 0;
- define_config("", 0);
+ struct item *aux, *next;
+ unsigned int i;
+
+ for (i = 0; i < HASHSZ; i++) {
+ for (aux = hashtab[i]; aux; aux = next) {
+ next = aux->next;
+ free(aux);
+ }
+ hashtab[i] = NULL;
+ }
}
/*
* Record the use of a CONFIG_* word.
*/
-static void use_config(char *m, int slen)
+static void use_config(const char *m, int slen)
{
- char s[PATH_MAX];
- char *p;
+ unsigned int hash = strhash(m, slen);
+ int c, i;
- if (is_defined_config(m, slen))
+ if (is_defined_config(m, slen, hash))
return;
- define_config(m, slen);
-
- memcpy(s, m, slen); s[slen] = 0;
+ define_config(m, slen, hash);
- for (p = s; p < s + slen; p++) {
- if (*p == '_')
- *p = '/';
+ printf(" $(wildcard include/config/");
+ for (i = 0; i < slen; i++) {
+ c = m[i];
+ if (c == '_')
+ c = '/';
else
- *p = tolower((int)*p);
+ c = tolower(c);
+ putchar(c);
}
- printf(" $(wildcard include/config/%s.h) \\\n", s);
+ printf(".h) \\\n");
}
-static void parse_config_file(char *map, size_t len)
+static void parse_config_file(const char *map, size_t len)
{
- int *end = (int *) (map + len);
+ const int *end = (const int *) (map + len);
/* start at +1, so that p can never be < map */
- int *m = (int *) map + 1;
- char *p, *q;
+ const int *m = (const int *) map + 1;
+ const char *p, *q;
for (; m < end; m++) {
if (*m == INT_CONF) { p = (char *) m ; goto conf; }
@@ -265,7 +278,7 @@ static int strrcmp(char *s, char *sub)
return memcmp(s + slen - sublen, sub, sublen);
}
-static void do_config_file(char *filename)
+static void do_config_file(const char *filename)
{
struct stat st;
int fd;