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>hifive-unleashed-5.1
Eric Dumazet
Michal Marek
parent
d63f6d1b4d
commit
8af27e1dc4
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@ -138,38 +138,36 @@ static void print_cmdline(void)
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printf("cmd_%s := %s\n\n", target, cmdline);
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}
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char * str_config = NULL;
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int size_config = 0;
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int len_config = 0;
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struct item {
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struct item *next;
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unsigned int len;
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unsigned int hash;
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char name[0];
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};
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/*
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* Grow the configuration string to a desired length.
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* Usually the first growth is plenty.
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*/
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static void grow_config(int len)
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#define HASHSZ 256
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static struct item *hashtab[HASHSZ];
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static unsigned int strhash(const char *str, unsigned int sz)
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{
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while (len_config + len > size_config) {
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if (size_config == 0)
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size_config = 2048;
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str_config = realloc(str_config, size_config *= 2);
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if (str_config == NULL)
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{ perror("fixdep:malloc"); exit(1); }
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}
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/* fnv32 hash */
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unsigned int i, hash = 2166136261U;
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for (i = 0; i < sz; i++)
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hash = (hash ^ str[i]) * 0x01000193;
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return hash;
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}
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/*
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* Lookup a value in the configuration string.
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*/
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static int is_defined_config(const char * name, int len)
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static int is_defined_config(const char *name, int len, unsigned int hash)
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{
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const char * pconfig;
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const char * plast = str_config + len_config - len;
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for ( pconfig = str_config + 1; pconfig < plast; pconfig++ ) {
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if (pconfig[ -1] == '\n'
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&& pconfig[len] == '\n'
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&& !memcmp(pconfig, name, len))
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struct item *aux;
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for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) {
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if (aux->hash == hash && aux->len == len &&
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memcmp(aux->name, name, len) == 0)
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return 1;
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}
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return 0;
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@ -178,13 +176,19 @@ static int is_defined_config(const char * name, int len)
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/*
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* Add a new value to the configuration string.
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*/
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static void define_config(const char * name, int len)
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static void define_config(const char *name, int len, unsigned int hash)
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{
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grow_config(len + 1);
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struct item *aux = malloc(sizeof(*aux) + len);
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memcpy(str_config+len_config, name, len);
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len_config += len;
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str_config[len_config++] = '\n';
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if (!aux) {
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perror("fixdep:malloc");
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exit(1);
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}
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memcpy(aux->name, name, len);
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aux->len = len;
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aux->hash = hash;
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aux->next = hashtab[hash % HASHSZ];
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hashtab[hash % HASHSZ] = aux;
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}
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/*
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@ -192,40 +196,49 @@ static void define_config(const char * name, int len)
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*/
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static void clear_config(void)
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{
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len_config = 0;
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define_config("", 0);
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struct item *aux, *next;
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unsigned int i;
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for (i = 0; i < HASHSZ; i++) {
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for (aux = hashtab[i]; aux; aux = next) {
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next = aux->next;
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free(aux);
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}
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hashtab[i] = NULL;
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}
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}
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/*
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* Record the use of a CONFIG_* word.
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*/
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static void use_config(char *m, int slen)
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static void use_config(const char *m, int slen)
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{
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char s[PATH_MAX];
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char *p;
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unsigned int hash = strhash(m, slen);
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int c, i;
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if (is_defined_config(m, slen))
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if (is_defined_config(m, slen, hash))
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return;
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define_config(m, slen);
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define_config(m, slen, hash);
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memcpy(s, m, slen); s[slen] = 0;
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for (p = s; p < s + slen; p++) {
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if (*p == '_')
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*p = '/';
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printf(" $(wildcard include/config/");
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for (i = 0; i < slen; i++) {
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c = m[i];
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if (c == '_')
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c = '/';
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else
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*p = tolower((int)*p);
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c = tolower(c);
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putchar(c);
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}
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printf(" $(wildcard include/config/%s.h) \\\n", s);
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printf(".h) \\\n");
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}
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static void parse_config_file(char *map, size_t len)
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static void parse_config_file(const char *map, size_t len)
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{
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int *end = (int *) (map + len);
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const int *end = (const int *) (map + len);
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/* start at +1, so that p can never be < map */
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int *m = (int *) map + 1;
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char *p, *q;
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const int *m = (const int *) map + 1;
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const char *p, *q;
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for (; m < end; m++) {
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if (*m == INT_CONF) { p = (char *) m ; goto conf; }
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@ -265,7 +278,7 @@ static int strrcmp(char *s, char *sub)
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return memcmp(s + slen - sublen, sub, sublen);
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}
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static void do_config_file(char *filename)
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static void do_config_file(const char *filename)
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{
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struct stat st;
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int fd;
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