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synced 2024-11-05 05:52:15 +03:00
qemu-io-cmds: use clock_gettime for benchmarking
The previous use of gettimeofday() ran into undefined behaviour when we ended up doing a div 0 for a very short operation. This is because gettimeofday only works at the microsecond level as well as being prone to discontinuous jumps in system time. Using clock_gettime with CLOCK_MONOTONIC gives greater precision and alleviates some of the potential problems with time jumping around. We could use CLOCK_MONOTONIC_RAW to avoid being tripped up by NTP and adjtime but that is Linux specific so I decided it would do for now. Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
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9b109f566a
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50290c002c
@ -248,20 +248,21 @@ static void cvtstr(double value, char *str, size_t size)
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static struct timeval tsub(struct timeval t1, struct timeval t2)
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static struct timespec tsub(struct timespec t1, struct timespec t2)
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{
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t1.tv_usec -= t2.tv_usec;
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if (t1.tv_usec < 0) {
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t1.tv_usec += 1000000;
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t1.tv_nsec -= t2.tv_nsec;
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if (t1.tv_nsec < 0) {
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t1.tv_nsec += NANOSECONDS_PER_SECOND;
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t1.tv_sec--;
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}
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t1.tv_sec -= t2.tv_sec;
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return t1;
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}
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static double tdiv(double value, struct timeval tv)
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static double tdiv(double value, struct timespec tv)
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{
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return value / ((double)tv.tv_sec + ((double)tv.tv_usec / 1000000.0));
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double seconds = tv.tv_sec + (tv.tv_nsec / 1e9);
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return value / seconds;
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}
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#define HOURS(sec) ((sec) / (60 * 60))
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@ -274,29 +275,27 @@ enum {
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VERBOSE_FIXED_TIME = 0x2,
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};
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static void timestr(struct timeval *tv, char *ts, size_t size, int format)
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static void timestr(struct timespec *tv, char *ts, size_t size, int format)
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{
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double usec = (double)tv->tv_usec / 1000000.0;
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double frac_sec = tv->tv_nsec / 1e9;
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if (format & TERSE_FIXED_TIME) {
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if (!HOURS(tv->tv_sec)) {
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snprintf(ts, size, "%u:%02u.%02u",
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(unsigned int) MINUTES(tv->tv_sec),
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(unsigned int) SECONDS(tv->tv_sec),
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(unsigned int) (usec * 100));
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snprintf(ts, size, "%u:%05.2f",
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(unsigned int) MINUTES(tv->tv_sec),
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SECONDS(tv->tv_sec) + frac_sec);
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return;
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}
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format |= VERBOSE_FIXED_TIME; /* fallback if hours needed */
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}
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if ((format & VERBOSE_FIXED_TIME) || tv->tv_sec) {
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snprintf(ts, size, "%u:%02u:%02u.%02u",
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snprintf(ts, size, "%u:%02u:%05.2f",
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(unsigned int) HOURS(tv->tv_sec),
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(unsigned int) MINUTES(tv->tv_sec),
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(unsigned int) SECONDS(tv->tv_sec),
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(unsigned int) (usec * 100));
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SECONDS(tv->tv_sec) + frac_sec);
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} else {
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snprintf(ts, size, "0.%04u sec", (unsigned int) (usec * 10000));
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snprintf(ts, size, "%05.2f sec", frac_sec);
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}
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}
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@ -376,7 +375,7 @@ static void dump_buffer(const void *buffer, int64_t offset, int64_t len)
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}
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}
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static void print_report(const char *op, struct timeval *t, int64_t offset,
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static void print_report(const char *op, struct timespec *t, int64_t offset,
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int64_t count, int64_t total, int cnt, bool Cflag)
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{
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char s1[64], s2[64], ts[64];
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@ -649,7 +648,7 @@ static const cmdinfo_t read_cmd = {
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static int read_f(BlockBackend *blk, int argc, char **argv)
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{
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struct timeval t1, t2;
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struct timespec t1, t2;
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bool Cflag = false, qflag = false, vflag = false;
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bool Pflag = false, sflag = false, lflag = false, bflag = false;
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int c, cnt, ret;
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@ -758,13 +757,13 @@ static int read_f(BlockBackend *blk, int argc, char **argv)
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buf = qemu_io_alloc(blk, count, 0xab);
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gettimeofday(&t1, NULL);
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clock_gettime(CLOCK_MONOTONIC, &t1);
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if (bflag) {
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ret = do_load_vmstate(blk, buf, offset, count, &total);
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} else {
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ret = do_pread(blk, buf, offset, count, &total);
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}
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gettimeofday(&t2, NULL);
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clock_gettime(CLOCK_MONOTONIC, &t2);
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if (ret < 0) {
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printf("read failed: %s\n", strerror(-ret));
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@ -836,7 +835,7 @@ static const cmdinfo_t readv_cmd = {
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static int readv_f(BlockBackend *blk, int argc, char **argv)
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{
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struct timeval t1, t2;
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struct timespec t1, t2;
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bool Cflag = false, qflag = false, vflag = false;
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int c, cnt, ret;
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char *buf;
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@ -891,9 +890,9 @@ static int readv_f(BlockBackend *blk, int argc, char **argv)
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return -EINVAL;
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}
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gettimeofday(&t1, NULL);
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clock_gettime(CLOCK_MONOTONIC, &t1);
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ret = do_aio_readv(blk, &qiov, offset, &total);
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gettimeofday(&t2, NULL);
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clock_gettime(CLOCK_MONOTONIC, &t2);
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if (ret < 0) {
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printf("readv failed: %s\n", strerror(-ret));
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@ -972,7 +971,7 @@ static const cmdinfo_t write_cmd = {
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static int write_f(BlockBackend *blk, int argc, char **argv)
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{
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struct timeval t1, t2;
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struct timespec t1, t2;
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bool Cflag = false, qflag = false, bflag = false;
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bool Pflag = false, zflag = false, cflag = false;
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int flags = 0;
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@ -1091,7 +1090,7 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
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buf = qemu_io_alloc(blk, count, pattern);
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}
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gettimeofday(&t1, NULL);
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clock_gettime(CLOCK_MONOTONIC, &t1);
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if (bflag) {
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ret = do_save_vmstate(blk, buf, offset, count, &total);
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} else if (zflag) {
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@ -1101,7 +1100,7 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
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} else {
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ret = do_pwrite(blk, buf, offset, count, flags, &total);
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}
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gettimeofday(&t2, NULL);
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clock_gettime(CLOCK_MONOTONIC, &t2);
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if (ret < 0) {
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printf("write failed: %s\n", strerror(-ret));
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@ -1160,7 +1159,7 @@ static const cmdinfo_t writev_cmd = {
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static int writev_f(BlockBackend *blk, int argc, char **argv)
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{
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struct timeval t1, t2;
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struct timespec t1, t2;
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bool Cflag = false, qflag = false;
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int flags = 0;
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int c, cnt, ret;
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@ -1213,9 +1212,9 @@ static int writev_f(BlockBackend *blk, int argc, char **argv)
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return -EINVAL;
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}
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gettimeofday(&t1, NULL);
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clock_gettime(CLOCK_MONOTONIC, &t1);
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ret = do_aio_writev(blk, &qiov, offset, flags, &total);
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gettimeofday(&t2, NULL);
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clock_gettime(CLOCK_MONOTONIC, &t2);
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if (ret < 0) {
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printf("writev failed: %s\n", strerror(-ret));
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@ -1250,15 +1249,15 @@ struct aio_ctx {
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bool zflag;
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BlockAcctCookie acct;
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int pattern;
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struct timeval t1;
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struct timespec t1;
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};
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static void aio_write_done(void *opaque, int ret)
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{
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struct aio_ctx *ctx = opaque;
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struct timeval t2;
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struct timespec t2;
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gettimeofday(&t2, NULL);
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clock_gettime(CLOCK_MONOTONIC, &t2);
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if (ret < 0) {
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@ -1288,9 +1287,9 @@ out:
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static void aio_read_done(void *opaque, int ret)
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{
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struct aio_ctx *ctx = opaque;
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struct timeval t2;
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struct timespec t2;
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gettimeofday(&t2, NULL);
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clock_gettime(CLOCK_MONOTONIC, &t2);
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if (ret < 0) {
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printf("readv failed: %s\n", strerror(-ret));
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@ -1425,7 +1424,7 @@ static int aio_read_f(BlockBackend *blk, int argc, char **argv)
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return -EINVAL;
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}
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gettimeofday(&ctx->t1, NULL);
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clock_gettime(CLOCK_MONOTONIC, &ctx->t1);
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block_acct_start(blk_get_stats(blk), &ctx->acct, ctx->qiov.size,
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BLOCK_ACCT_READ);
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blk_aio_preadv(blk, ctx->offset, &ctx->qiov, 0, aio_read_done, ctx);
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@ -1570,7 +1569,7 @@ static int aio_write_f(BlockBackend *blk, int argc, char **argv)
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return -EINVAL;
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}
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gettimeofday(&ctx->t1, NULL);
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clock_gettime(CLOCK_MONOTONIC, &ctx->t1);
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block_acct_start(blk_get_stats(blk), &ctx->acct, ctx->qiov.size,
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BLOCK_ACCT_WRITE);
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@ -1746,7 +1745,7 @@ static const cmdinfo_t discard_cmd = {
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static int discard_f(BlockBackend *blk, int argc, char **argv)
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{
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struct timeval t1, t2;
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struct timespec t1, t2;
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bool Cflag = false, qflag = false;
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int c, ret;
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int64_t offset, bytes;
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@ -1787,9 +1786,9 @@ static int discard_f(BlockBackend *blk, int argc, char **argv)
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return -EINVAL;
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}
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gettimeofday(&t1, NULL);
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clock_gettime(CLOCK_MONOTONIC, &t1);
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ret = blk_pdiscard(blk, offset, bytes);
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gettimeofday(&t2, NULL);
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clock_gettime(CLOCK_MONOTONIC, &t2);
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if (ret < 0) {
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printf("discard failed: %s\n", strerror(-ret));
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