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c3122bca5

Denis Vlasenko
Denis Vlasenko
2007-09-28
FAILED Duration: 19s

Subject

hdparm: simplify timing measurement (it wa the last last user of setitimer in the tree).

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

miscutils/hdparm.c +62 -64
miscutils/hdparm.c+62 -64
@@ -429,10 +429,8 @@ static const char *const secu_str[] = {
#define SIG 0x00ff /* signature location */
#define SIG_VAL 0x00a5 /* signature value */
-#define TIMING_MB 64
#define TIMING_BUF_MB 1
#define TIMING_BUF_BYTES (TIMING_BUF_MB * 1024 * 1024)
-#define BUFCACHE_FACTOR 2
#undef DO_FLUSHCACHE /* under construction: force cache flush on -W0 */
@@ -505,6 +503,9 @@ struct globals {
unsigned long hwif_ctrl;
unsigned long hwif_irq;
#endif
+#ifdef DO_FLUSHCACHE
+ unsigned char flushcache[4] = { WIN_FLUSHCACHE, 0, 0, 0 };
+#endif
};
#define G (*(struct globals*)&bb_common_bufsiz1)
struct BUG_G_too_big {
@@ -1342,22 +1343,17 @@ static void seek_to_zero(/*int fd*/ void)
xlseek(fd, (off_t) 0, SEEK_SET);
}
-static int read_big_block(/*int fd,*/ char *buf)
+static void read_big_block(/*int fd,*/ char *buf)
{
int i;
- i = read(fd, buf, TIMING_BUF_BYTES);
- if (i != TIMING_BUF_BYTES) {
- bb_error_msg("read(%d bytes) failed (rc=%d)", TIMING_BUF_BYTES, i);
- return 1;
- }
+ xread(fd, buf, TIMING_BUF_BYTES);
/* access all sectors of buf to ensure the read fully completed */
for (i = 0; i < TIMING_BUF_BYTES; i += 512)
buf[i] &= 1;
- return 0;
}
-static unsigned long long do_blkgetsize(/*int fd*/ void)
+static unsigned long long dev_size_mb(/*int fd*/ void)
{
union {
unsigned long long blksize64;
@@ -1365,85 +1361,88 @@ static unsigned long long do_blkgetsize(/*int fd*/ void)
} u;
if (0 == ioctl(fd, BLKGETSIZE64, &u.blksize64)) { // returns bytes
- return u.blksize64 / 512;
+ return u.blksize64 / (1024 * 1024);
}
xioctl(fd, BLKGETSIZE, &u.blksize32); // returns sectors
- return u.blksize32;
+ return u.blksize32 / (2 * 1024);
}
-static void print_timing(unsigned t, double e)
+static void print_timing(unsigned long m, unsigned elapsed_us)
{
- if (t >= e) /* more than 1MB/s */
- printf("%4d MB in %.2f seconds = %.2f %cB/sec\n", t, e, t / e, 'M');
- else
- printf("%4d MB in %.2f seconds = %.2f %cB/sec\n", t, e, t / e * 1024, 'k');
+ unsigned sec = elapsed_us / 1000000;
+ unsigned hs = (elapsed_us % 1000000) / 10000;
+
+ printf("%5lu MB in %u.%02u seconds = %lu kB/s\n",
+ m, sec, hs,
+ /* Trying to not overflow 32-bit arith in m * CONST
+ * by keeping CONST not so big. + 1 prevents div-by-0. */
+ (m * (1024 * 1000000 / (64*1024))) / (elapsed_us / (64*1024) + 1)
+ // ~= (m * 1024 * 1000000) / elapsed_ms
+ // = (m * 1024) / (elapsed_ms / 1000000)
+ // = kb / elapsed_sec
+ );
}
-static void do_time(int flag /*,int fd*/)
-/* flag = 0 time_cache, 1 time_device */
+static void do_time(int cache /*,int fd*/)
+/* cache=1: time cache: repeatedly read N MB at offset 0
+ * cache=0: time device: linear read, starting at offset 0
+ */
{
- static const struct itimerval thousand = {{1000, 0}, {1000, 0}};
-
- struct itimerval itv;
+ unsigned max_iterations, iterations;
+ unsigned start; /* don't need to be long long */
unsigned elapsed, elapsed2;
- unsigned max_iterations, total_MB, iterations;
+ unsigned long total_MB;
char *buf = xmalloc(TIMING_BUF_BYTES);
- if (mlock(buf, TIMING_BUF_BYTES)) {
- bb_perror_msg("mlock");
- goto quit2;
- }
+ if (mlock(buf, TIMING_BUF_BYTES))
+ bb_perror_msg_and_die("mlock");
- max_iterations = do_blkgetsize() / (2 * 1024) / TIMING_BUF_MB;
+ /* Don't want to read past the end! */
+ max_iterations = UINT_MAX;
+ if (!cache)
+ max_iterations = dev_size_mb() / TIMING_BUF_MB;
- /* Clear out the device request queues & give them time to complete */
+ /* Clear out the device request queues & give them time to complete.
+ * NB: *small* delay. User is expected to have a clue and to not run
+ * heavy io in parallel with measurements. */
sync();
- sleep(2);
- if (flag == 0) { /* Time cache */
+ sleep(1);
+ if (cache) { /* Time cache */
seek_to_zero();
- if (read_big_block(buf))
- goto quit;
- printf(" Timing buffer-cache reads: ");
+ read_big_block(buf);
+ printf("Timing buffer-cache reads: ");
} else { /* Time device */
- printf(" Timing buffered disk reads: ");
+ printf("Timing buffered disk reads:");
}
fflush(stdout);
- iterations = 0;
- /*
- * getitimer() is used rather than gettimeofday() because
- * it is much more consistent (on my machine, at least).
- */
-//TODO: get rid of
- setitimer(ITIMER_REAL, &thousand, NULL);
+
/* Now do the timing */
+ iterations = 0;
+ start = monotonic_us();
do {
- ++iterations;
- if (flag == 0)
+ if (cache)
seek_to_zero();
- if (read_big_block(buf))
- goto quit;
- getitimer(ITIMER_REAL, &itv);
- elapsed = (1000 - itv.it_value.tv_sec) * 1000000
- - itv.it_value.tv_usec;
+ read_big_block(buf);
+ elapsed = (unsigned)monotonic_us() - start;
+ ++iterations;
} while (elapsed < 3000000 && iterations < max_iterations);
- total_MB = iterations * TIMING_BUF_MB;
- if (flag == 0) {
- /* Now remove the lseek() and getitimer() overheads from the elapsed time */
- setitimer(ITIMER_REAL, &thousand, NULL);
+ total_MB = (unsigned long)iterations * TIMING_BUF_MB;
+ //printf(" elapsed:%u iterations:%u ", elapsed, iterations);
+ if (cache) {
+ /* Now remove the lseek() and monotonic_us() overheads
+ * from elapsed */
+ start = monotonic_us();
do {
seek_to_zero();
- getitimer(ITIMER_REAL, &itv);
- elapsed2 = (1000 - itv.it_value.tv_sec) * 1000000
- - itv.it_value.tv_usec;
+ elapsed2 = (unsigned)monotonic_us() - start;
} while (--iterations);
+ //printf(" elapsed2:%u ", elapsed2);
elapsed -= elapsed2;
- total_MB *= BUFCACHE_FACTOR;
+ total_MB *= 2; // BUFCACHE_FACTOR (why?)
flush_buffer_cache();
}
- print_timing(total_MB, elapsed / 1000000.0);
- quit:
+ print_timing(total_MB, elapsed);
munlock(buf, TIMING_BUF_BYTES);
- quit2:
free(buf);
}
@@ -1688,7 +1687,6 @@ static void process_dev(char *devname)
#ifndef WIN_FLUSHCACHE
#define WIN_FLUSHCACHE 0xe7
#endif
- static unsigned char flushcache[4] = { WIN_FLUSHCACHE, 0, 0, 0 };
#endif /* DO_FLUSHCACHE */
args[2] = wcache ? 0x02 : 0x82;
print_flag_on_off(get_wcache, "drive write-caching", wcache);
@@ -1749,7 +1747,7 @@ static void process_dev(char *devname)
char buf[512];
flush_buffer_cache();
if (-1 == read(fd, buf, sizeof(buf)))
- bb_perror_msg("read(%d bytes) failed (rc=%d)", sizeof(buf), -1);
+ bb_perror_msg("read(%d bytes) failed (rc=-1)", sizeof(buf));
}
#endif /* HDIO_DRIVE_CMD */
@@ -1912,9 +1910,9 @@ static void process_dev(char *devname)
ioctl_or_warn(fd, BLKRRPART, NULL);
if (do_ctimings)
- do_time(0 /*,fd*/); /* time cache */
+ do_time(1 /*,fd*/); /* time cache */
if (do_timings)
- do_time(1 /*,fd*/); /* time device */
+ do_time(0 /*,fd*/); /* time device */
if (do_flush)
flush_buffer_cache();
close(fd);