diff options
| author | Richard Henderson <richard.henderson@linaro.org> | 2020-06-26 13:09:49 -0700 |
|---|---|---|
| committer | Alex Bennée <alex.bennee@linaro.org> | 2020-07-11 15:53:00 +0100 |
| commit | d11f824991749c4b28c3c08ca737e82d0d9d01e6 (patch) | |
| tree | 61634d397fb842ad511034eb40f0c9a524edab1b /tests/qht-bench.c | |
| parent | 100a5efbbcffef50d187c045492bcd09d871845e (diff) | |
tests/qht-bench: Adjust testing rate by -1
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>
Diffstat (limited to 'tests/qht-bench.c')
| -rw-r--r-- | tests/qht-bench.c | 22 |
1 files changed, 15 insertions, 7 deletions
diff --git a/tests/qht-bench.c b/tests/qht-bench.c index eb88a90137..ad885d89d0 100644 --- a/tests/qht-bench.c +++ b/tests/qht-bench.c @@ -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 */ |