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tests: benchmark crypto with fixed data size, not time period

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Currently the crypto benchmarks are processing data in varying chunk
sizes, over a fixed time period. This turns out to be a terrible idea
because with small chunk sizes the overhead of checking the elapsed
time on each loop iteration masks the true performance.

Benchmarking over a fixed data size avoids the loop running any system
calls which can interfere with the performance measurements.

Before this change

Enc chunk 512 bytes 2283.47 MB/sec Dec chunk 512 bytes 2236.23 MB/sec OK
Enc chunk 4096 bytes 2744.97 MB/sec Dec chunk 4096 bytes 2614.71 MB/sec OK
Enc chunk 16384 bytes 2777.53 MB/sec Dec chunk 16384 bytes 2678.44 MB/sec OK
Enc chunk 65536 bytes 2809.34 MB/sec Dec chunk 65536 bytes 2699.47 MB/sec OK

After this change

Enc chunk 512 bytes 2058.22 MB/sec Dec chunk 512 bytes 2030.11 MB/sec OK
Enc chunk 4096 bytes 2699.27 MB/sec Dec chunk 4096 bytes 2573.78 MB/sec OK
Enc chunk 16384 bytes 2748.52 MB/sec Dec chunk 16384 bytes 2653.76 MB/sec OK
Enc chunk 65536 bytes 2814.08 MB/sec Dec chunk 65536 bytes 2712.74 MB/sec OK

The actual crypto performance hasn't changed, which shows how
significant the mis-measurement has been for small data sizes.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
This commit is contained in:
Daniel P. Berrangé 2019-10-17 14:22:19 +01:00
parent e2186a3606
commit b4296d7f88
2 changed files with 23 additions and 20 deletions
Download patch file Download diff file Expand all files Collapse all files

26
tests/benchmark-crypto-cipher.c
View file

@ -21,11 +21,12 @@ static void test_cipher_speed(size_t chunk_size,
{
QCryptoCipher *cipher;
Error *err = NULL;
double total = 0.0;
uint8_t *key = NULL, *iv = NULL;
uint8_t *plaintext = NULL, *ciphertext = NULL;
size_t nkey;
size_t niv;
const size_t total = 2 * GiB;
size_t remain;
if (!qcrypto_cipher_supports(alg, mode)) {
return;
@ -58,33 +59,34 @@ static void test_cipher_speed(size_t chunk_size,
&err) == 0);
g_test_timer_start();
do {
remain = total;
while (remain) {
g_assert(qcrypto_cipher_encrypt(cipher,
plaintext,
ciphertext,
chunk_size,
&err) == 0);
total += chunk_size;
} while (g_test_timer_elapsed() < 1.0);
remain -= chunk_size;
}
g_test_timer_elapsed();
total /= MiB;
g_print("Enc chunk %zu bytes ", chunk_size);
g_print("%.2f MB/sec ", total / g_test_timer_last());
g_print("%.2f MB/sec ", (double)total / MiB / g_test_timer_last());
total = 0.0;
g_test_timer_start();
do {
remain = total;
while (remain) {
g_assert(qcrypto_cipher_decrypt(cipher,
plaintext,
ciphertext,
chunk_size,
&err) == 0);
total += chunk_size;
} while (g_test_timer_elapsed() < 1.0);
remain -= chunk_size;
}
g_test_timer_elapsed();
total /= MiB;
g_print("Dec chunk %zu bytes ", chunk_size);
g_print("%.2f MB/sec ", total / g_test_timer_last());
g_print("%.2f MB/sec ", (double)total / MiB / g_test_timer_last());
qcrypto_cipher_free(cipher);
g_free(plaintext);