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authorMahmoud Mandour <ma.mandourr@gmail.com>2021-08-03 17:13:00 +0200
committerAlex Bennée <alex.bennee@linaro.org>2021-09-02 11:29:34 +0100
commitc79a2116af6ad5a923e1bf127a78e8089e315021 (patch)
treec216f61652c1c1e12436ea367365865f86a71736 /contrib
parentb906acace2d4f68b6ff8de73739a773cc4851436 (diff)
plugins/cache: supported multicore cache modelling
Multicore L1 cache modelling is introduced and is supported for both full system emulation and linux-user. For full-system emulation, L1 icache and dcache are maintained for each available core, since this information is exposed to the plugin through `qemu_plugin_n_vcpus()`. For linux-user, a static number of cores is assumed (default 1 core, and can be provided as a plugin argument `cores=N`). Every memory access goes through one of these caches, this approach is taken as it's somewhat akin to what happens on real setup, where a program that dispatches more threads than the available cores, they'll thrash each other Signed-off-by: Mahmoud Mandour <ma.mandourr@gmail.com> Message-Id: <20210803151301.123581-2-ma.mandourr@gmail.com> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Diffstat (limited to 'contrib')
-rw-r--r--contrib/plugins/cache.c176
1 files changed, 132 insertions, 44 deletions
diff --git a/contrib/plugins/cache.c b/contrib/plugins/cache.c
index 066ea6d8ec..a1e03ca882 100644
--- a/contrib/plugins/cache.c
+++ b/contrib/plugins/cache.c
@@ -17,18 +17,12 @@ static enum qemu_plugin_mem_rw rw = QEMU_PLUGIN_MEM_RW;
static GHashTable *miss_ht;
-static GMutex mtx;
+static GMutex hashtable_lock;
static GRand *rng;
static int limit;
static bool sys;
-static uint64_t dmem_accesses;
-static uint64_t dmisses;
-
-static uint64_t imem_accesses;
-static uint64_t imisses;
-
enum EvictionPolicy {
LRU,
FIFO,
@@ -80,6 +74,8 @@ typedef struct {
int blksize_shift;
uint64_t set_mask;
uint64_t tag_mask;
+ uint64_t accesses;
+ uint64_t misses;
} Cache;
typedef struct {
@@ -96,7 +92,16 @@ void (*update_miss)(Cache *cache, int set, int blk);
void (*metadata_init)(Cache *cache);
void (*metadata_destroy)(Cache *cache);
-Cache *dcache, *icache;
+static int cores;
+static Cache **dcaches, **icaches;
+
+static GMutex *dcache_locks;
+static GMutex *icache_locks;
+
+static uint64_t all_dmem_accesses;
+static uint64_t all_imem_accesses;
+static uint64_t all_imisses;
+static uint64_t all_dmisses;
static int pow_of_two(int num)
{
@@ -233,20 +238,24 @@ static bool bad_cache_params(int blksize, int assoc, int cachesize)
static Cache *cache_init(int blksize, int assoc, int cachesize)
{
- if (bad_cache_params(blksize, assoc, cachesize)) {
- return NULL;
- }
-
Cache *cache;
int i;
uint64_t blk_mask;
+ /*
+ * This function shall not be called directly, and hence expects suitable
+ * parameters.
+ */
+ g_assert(!bad_cache_params(blksize, assoc, cachesize));
+
cache = g_new(Cache, 1);
cache->assoc = assoc;
cache->cachesize = cachesize;
cache->num_sets = cachesize / (blksize * assoc);
cache->sets = g_new(CacheSet, cache->num_sets);
cache->blksize_shift = pow_of_two(blksize);
+ cache->accesses = 0;
+ cache->misses = 0;
for (i = 0; i < cache->num_sets; i++) {
cache->sets[i].blocks = g_new0(CacheBlock, assoc);
@@ -263,6 +272,24 @@ static Cache *cache_init(int blksize, int assoc, int cachesize)
return cache;
}
+static Cache **caches_init(int blksize, int assoc, int cachesize)
+{
+ Cache **caches;
+ int i;
+
+ if (bad_cache_params(blksize, assoc, cachesize)) {
+ return NULL;
+ }
+
+ caches = g_new(Cache *, cores);
+
+ for (i = 0; i < cores; i++) {
+ caches[i] = cache_init(blksize, assoc, cachesize);
+ }
+
+ return caches;
+}
+
static int get_invalid_block(Cache *cache, uint64_t set)
{
int i;
@@ -353,6 +380,7 @@ static void vcpu_mem_access(unsigned int vcpu_index, qemu_plugin_meminfo_t info,
{
uint64_t effective_addr;
struct qemu_plugin_hwaddr *hwaddr;
+ int cache_idx;
InsnData *insn;
hwaddr = qemu_plugin_get_hwaddr(info, vaddr);
@@ -361,32 +389,35 @@ static void vcpu_mem_access(unsigned int vcpu_index, qemu_plugin_meminfo_t info,
}
effective_addr = hwaddr ? qemu_plugin_hwaddr_phys_addr(hwaddr) : vaddr;
+ cache_idx = vcpu_index % cores;
- g_mutex_lock(&mtx);
- if (!access_cache(dcache, effective_addr)) {
+ g_mutex_lock(&dcache_locks[cache_idx]);
+ if (!access_cache(dcaches[cache_idx], effective_addr)) {
insn = (InsnData *) userdata;
- insn->dmisses++;
- dmisses++;
+ __atomic_fetch_add(&insn->dmisses, 1, __ATOMIC_SEQ_CST);
+ dcaches[cache_idx]->misses++;
}
- dmem_accesses++;
- g_mutex_unlock(&mtx);
+ dcaches[cache_idx]->accesses++;
+ g_mutex_unlock(&dcache_locks[cache_idx]);
}
static void vcpu_insn_exec(unsigned int vcpu_index, void *userdata)
{
uint64_t insn_addr;
InsnData *insn;
+ int cache_idx;
- g_mutex_lock(&mtx);
insn_addr = ((InsnData *) userdata)->addr;
- if (!access_cache(icache, insn_addr)) {
+ cache_idx = vcpu_index % cores;
+ g_mutex_lock(&icache_locks[cache_idx]);
+ if (!access_cache(icaches[cache_idx], insn_addr)) {
insn = (InsnData *) userdata;
- insn->imisses++;
- imisses++;
+ __atomic_fetch_add(&insn->imisses, 1, __ATOMIC_SEQ_CST);
+ icaches[cache_idx]->misses++;
}
- imem_accesses++;
- g_mutex_unlock(&mtx);
+ icaches[cache_idx]->accesses++;
+ g_mutex_unlock(&icache_locks[cache_idx]);
}
static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
@@ -411,7 +442,7 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
* new entries for those instructions. Instead, we fetch the same
* entry from the hash table and register it for the callback again.
*/
- g_mutex_lock(&mtx);
+ g_mutex_lock(&hashtable_lock);
data = g_hash_table_lookup(miss_ht, GUINT_TO_POINTER(effective_addr));
if (data == NULL) {
data = g_new0(InsnData, 1);
@@ -421,7 +452,7 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
g_hash_table_insert(miss_ht, GUINT_TO_POINTER(effective_addr),
(gpointer) data);
}
- g_mutex_unlock(&mtx);
+ g_mutex_unlock(&hashtable_lock);
qemu_plugin_register_vcpu_mem_cb(insn, vcpu_mem_access,
QEMU_PLUGIN_CB_NO_REGS,
@@ -453,6 +484,15 @@ static void cache_free(Cache *cache)
g_free(cache);
}
+static void caches_free(Cache **caches)
+{
+ int i;
+
+ for (i = 0; i < cores; i++) {
+ cache_free(caches[i]);
+ }
+}
+
static int dcmp(gconstpointer a, gconstpointer b)
{
InsnData *insn_a = (InsnData *) a;
@@ -461,6 +501,37 @@ static int dcmp(gconstpointer a, gconstpointer b)
return insn_a->dmisses < insn_b->dmisses ? 1 : -1;
}
+static void append_stats_line(GString *line, uint64_t daccess, uint64_t dmisses,
+ uint64_t iaccess, uint64_t imisses)
+{
+ double dmiss_rate, imiss_rate;
+
+ dmiss_rate = ((double) dmisses) / (daccess) * 100.0;
+ imiss_rate = ((double) imisses) / (iaccess) * 100.0;
+
+ g_string_append_printf(line, "%-14lu %-12lu %9.4lf%% %-14lu %-12lu"
+ " %9.4lf%%\n",
+ daccess,
+ dmisses,
+ daccess ? dmiss_rate : 0.0,
+ iaccess,
+ imisses,
+ iaccess ? imiss_rate : 0.0);
+}
+
+static void sum_stats(void)
+{
+ int i;
+
+ g_assert(cores > 1);
+ for (i = 0; i < cores; i++) {
+ all_imisses += icaches[i]->misses;
+ all_dmisses += dcaches[i]->misses;
+ all_imem_accesses += icaches[i]->accesses;
+ all_dmem_accesses += dcaches[i]->accesses;
+ }
+}
+
static int icmp(gconstpointer a, gconstpointer b)
{
InsnData *insn_a = (InsnData *) a;
@@ -471,19 +542,29 @@ static int icmp(gconstpointer a, gconstpointer b)
static void log_stats(void)
{
- g_autoptr(GString) rep = g_string_new("");
- g_string_append_printf(rep,
- "Data accesses: %lu, Misses: %lu\nMiss rate: %lf%%\n\n",
- dmem_accesses,
- dmisses,
- ((double) dmisses / (double) dmem_accesses) * 100.0);
-
- g_string_append_printf(rep,
- "Instruction accesses: %lu, Misses: %lu\nMiss rate: %lf%%\n\n",
- imem_accesses,
- imisses,
- ((double) imisses / (double) imem_accesses) * 100.0);
+ int i;
+ Cache *icache, *dcache;
+
+ g_autoptr(GString) rep = g_string_new("core #, data accesses, data misses,"
+ " dmiss rate, insn accesses,"
+ " insn misses, imiss rate\n");
+
+ for (i = 0; i < cores; i++) {
+ g_string_append_printf(rep, "%-8d", i);
+ dcache = dcaches[i];
+ icache = icaches[i];
+ append_stats_line(rep, dcache->accesses, dcache->misses,
+ icache->accesses, icache->misses);
+ }
+
+ if (cores > 1) {
+ sum_stats();
+ g_string_append_printf(rep, "%-8s", "sum");
+ append_stats_line(rep, all_dmem_accesses, all_dmisses,
+ all_imem_accesses, all_imisses);
+ }
+ g_string_append(rep, "\n");
qemu_plugin_outs(rep->str);
}
@@ -530,8 +611,8 @@ static void plugin_exit(qemu_plugin_id_t id, void *p)
log_stats();
log_top_insns();
- cache_free(dcache);
- cache_free(icache);
+ caches_free(dcaches);
+ caches_free(icaches);
g_hash_table_destroy(miss_ht);
}
@@ -579,6 +660,8 @@ int qemu_plugin_install(qemu_plugin_id_t id, const qemu_info_t *info,
policy = LRU;
+ cores = sys ? qemu_plugin_n_vcpus() : 1;
+
for (i = 0; i < argc; i++) {
char *opt = argv[i];
if (g_str_has_prefix(opt, "iblksize=")) {
@@ -595,6 +678,8 @@ int qemu_plugin_install(qemu_plugin_id_t id, const qemu_info_t *info,
dcachesize = g_ascii_strtoll(opt + 11, NULL, 10);
} else if (g_str_has_prefix(opt, "limit=")) {
limit = g_ascii_strtoll(opt + 6, NULL, 10);
+ } else if (g_str_has_prefix(opt, "cores=")) {
+ cores = g_ascii_strtoll(opt + 6, NULL, 10);
} else if (g_str_has_prefix(opt, "evict=")) {
gchar *p = opt + 6;
if (g_strcmp0(p, "rand") == 0) {
@@ -615,22 +700,25 @@ int qemu_plugin_install(qemu_plugin_id_t id, const qemu_info_t *info,
policy_init();
- dcache = cache_init(dblksize, dassoc, dcachesize);
- if (!dcache) {
+ dcaches = caches_init(dblksize, dassoc, dcachesize);
+ if (!dcaches) {
const char *err = cache_config_error(dblksize, dassoc, dcachesize);
fprintf(stderr, "dcache cannot be constructed from given parameters\n");
fprintf(stderr, "%s\n", err);
return -1;
}
- icache = cache_init(iblksize, iassoc, icachesize);
- if (!icache) {
+ icaches = caches_init(iblksize, iassoc, icachesize);
+ if (!icaches) {
const char *err = cache_config_error(iblksize, iassoc, icachesize);
fprintf(stderr, "icache cannot be constructed from given parameters\n");
fprintf(stderr, "%s\n", err);
return -1;
}
+ dcache_locks = g_new0(GMutex, cores);
+ icache_locks = g_new0(GMutex, cores);
+
qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans);
qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);