From: Ian Rogers Date: Mon, 12 May 2025 19:46:20 +0000 (-0700) Subject: perf fncache: Switch to using hashmap X-Git-Tag: v6.16-rc1~57^2~62 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=375368a9617dbf843e563d9deb6bf45751f6d770;p=linux-block.git perf fncache: Switch to using hashmap The existing fncache can get large in testing situations. As the bucket array is a fixed size this leads to it degrading to O(n) performance. Use a regular hashmap that can dynamically reallocate its array. Before: ``` $ time perf test "Parsing of PMU event table metrics" 10.3: Parsing of PMU event table metrics : Ok 10.4: Parsing of PMU event table metrics with fake PMUs : Ok real 0m14.132s user 0m17.806s sys 0m0.557s ``` After: ``` $ time perf test "Parsing of PMU event table metrics" 10.3: Parsing of PMU event table metrics : Ok 10.4: Parsing of PMU event table metrics with fake PMUs : Ok real 0m13.287s user 0m13.026s sys 0m0.532s ``` Committer notes: root@number:~# grep -m1 'model name' /proc/cpuinfo model name : AMD Ryzen 9 9950X3D 16-Core Processor root@number:~# Before: root@number:~# time perf test "Parsing of PMU event table metrics" 10.3: Parsing of PMU event table metrics : Ok 10.4: Parsing of PMU event table metrics with fake PMUs : Ok real 0m9.277s user 0m9.979s sys 0m0.055s root@number:~# After: root@number:~# time perf test "Parsing of PMU event table metrics" 10.3: Parsing of PMU event table metrics : Ok 10.4: Parsing of PMU event table metrics with fake PMUs : Ok real 0m9.296s user 0m9.361s sys 0m0.063s root@number:~# Signed-off-by: Ian Rogers Tested-by: Arnaldo Carvalho de Melo Tested-by: Namhyung Kim Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Kan Liang Cc: Mark Rutland Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Thomas Richter Cc: Xu Yang Link: https://lore.kernel.org/r/20250512194622.33258-2-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo --- diff --git a/tools/perf/util/fncache.c b/tools/perf/util/fncache.c index 6225cbc52310..bf9559c55c63 100644 --- a/tools/perf/util/fncache.c +++ b/tools/perf/util/fncache.c @@ -1,53 +1,58 @@ // SPDX-License-Identifier: GPL-2.0-only /* Manage a cache of file names' existence */ +#include #include -#include #include -#include +#include +#include #include "fncache.h" +#include "hashmap.h" -struct fncache { - struct hlist_node nd; - bool res; - char name[]; -}; +static struct hashmap *fncache; -#define FNHSIZE 61 +static size_t fncache__hash(long key, void *ctx __maybe_unused) +{ + return str_hash((const char *)key); +} -static struct hlist_head fncache_hash[FNHSIZE]; +static bool fncache__equal(long key1, long key2, void *ctx __maybe_unused) +{ + return strcmp((const char *)key1, (const char *)key2) == 0; +} -unsigned shash(const unsigned char *s) +static void fncache__init(void) { - unsigned h = 0; - while (*s) - h = 65599 * h + *s++; - return h ^ (h >> 16); + fncache = hashmap__new(fncache__hash, fncache__equal, /*ctx=*/NULL); +} + +static struct hashmap *fncache__get(void) +{ + static pthread_once_t fncache_once = PTHREAD_ONCE_INIT; + + pthread_once(&fncache_once, fncache__init); + + return fncache; } static bool lookup_fncache(const char *name, bool *res) { - int h = shash((const unsigned char *)name) % FNHSIZE; - struct fncache *n; - - hlist_for_each_entry(n, &fncache_hash[h], nd) { - if (!strcmp(n->name, name)) { - *res = n->res; - return true; - } - } - return false; + long val; + + if (!hashmap__find(fncache__get(), name, &val)) + return false; + + *res = (val != 0); + return true; } static void update_fncache(const char *name, bool res) { - struct fncache *n = malloc(sizeof(struct fncache) + strlen(name) + 1); - int h = shash((const unsigned char *)name) % FNHSIZE; - - if (!n) - return; - strcpy(n->name, name); - n->res = res; - hlist_add_head(&n->nd, &fncache_hash[h]); + char *old_key = NULL, *key = strdup(name); + + if (key) { + hashmap__set(fncache__get(), key, res, &old_key, /*old_value*/NULL); + free(old_key); + } } /* No LRU, only use when bounded in some other way. */ diff --git a/tools/perf/util/fncache.h b/tools/perf/util/fncache.h index fe020beaefb1..b6a0f209493e 100644 --- a/tools/perf/util/fncache.h +++ b/tools/perf/util/fncache.h @@ -1,7 +1,6 @@ #ifndef _FCACHE_H #define _FCACHE_H 1 -unsigned shash(const unsigned char *s); bool file_available(const char *name); #endif diff --git a/tools/perf/util/srccode.c b/tools/perf/util/srccode.c index 476e99896d5e..0f4907843ac1 100644 --- a/tools/perf/util/srccode.c +++ b/tools/perf/util/srccode.c @@ -16,7 +16,7 @@ #include "srccode.h" #include "debug.h" #include // page_size -#include "fncache.h" +#include "hashmap.h" #define MAXSRCCACHE (32*1024*1024) #define MAXSRCFILES 64 @@ -92,7 +92,7 @@ static struct srcfile *find_srcfile(char *fn) struct srcfile *h; int fd; unsigned long sz; - unsigned hval = shash((unsigned char *)fn) % SRC_HTAB_SZ; + size_t hval = str_hash(fn) % SRC_HTAB_SZ; hlist_for_each_entry (h, &srcfile_htab[hval], hash_nd) { if (!strcmp(fn, h->fn)) {