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tests/qht-bench: Adjust testing rate by -1

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Since the seed must be non-zero, subtracting 1 means puts the
rate in 0..UINT64_MAX-1, which allows the 0 and UINT64_MAX
thresholds to corrspond to 0% (never) and 100% (always).

Suggested-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200626200950.1015121-2-richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2020-06-26 13:09:49 -07:00 committed by Alex Bennée
parent 100a5efbbc
commit d11f824991
1 changed files with 15 additions and 7 deletions
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22
tests/qht-bench.c
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@ -25,7 +25,13 @@ struct thread_stats {
struct thread_info {
void (*func)(struct thread_info *);
struct thread_stats stats;
uint64_t r;
/*
* Seed is in the range [1..UINT64_MAX], because the RNG requires
* a non-zero seed. To use, subtract 1 and compare against the
* threshold with </>=. This lets threshold = 0 never match (0% hit),
* and threshold = UINT64_MAX always match (100% hit).
*/
uint64_t seed;
bool write_op; /* writes alternate between insertions and removals */
bool resize_down;
} QEMU_ALIGNED(64); /* avoid false sharing among threads */
@ -131,8 +137,9 @@ static uint64_t xorshift64star(uint64_t x)
static void do_rz(struct thread_info *info)
{
struct thread_stats *stats = &info->stats;
uint64_t r = info->seed - 1;
if (info->r < resize_threshold) {
if (r < resize_threshold) {
size_t size = info->resize_down ? resize_min : resize_max;
bool resized;
@ -151,13 +158,14 @@ static void do_rz(struct thread_info *info)
static void do_rw(struct thread_info *info)
{
struct thread_stats *stats = &info->stats;
uint64_t r = info->seed - 1;
uint32_t hash;
long *p;
if (info->r >= update_threshold) {
if (r >= update_threshold) {
bool read;
p = &keys[info->r & (lookup_range - 1)];
p = &keys[r & (lookup_range - 1)];
hash = hfunc(*p);
read = qht_lookup(&ht, p, hash);
if (read) {
@ -166,7 +174,7 @@ static void do_rw(struct thread_info *info)
stats->not_rd++;
}
} else {
p = &keys[info->r & (update_range - 1)];
p = &keys[r & (update_range - 1)];
hash = hfunc(*p);
if (info->write_op) {
bool written = false;
@ -208,7 +216,7 @@ static void *thread_func(void *p)
rcu_read_lock();
while (!atomic_read(&test_stop)) {
info->r = xorshift64star(info->r);
info->seed = xorshift64star(info->seed);
info->func(info);
}
rcu_read_unlock();
@ -221,7 +229,7 @@ static void *thread_func(void *p)
static void prepare_thread_info(struct thread_info *info, int i)
{
/* seed for the RNG; each thread should have a different one */
info->r = (i + 1) ^ time(NULL);
info->seed = (i + 1) ^ time(NULL);
/* the first update will be a write */
info->write_op = true;
/* the first resize will be down */