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hdparm: more robust (re overflows) code. +38 bytes.

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This commit is contained in:
Denis Vlasenko 2007-09-28 13:38:08 +00:00
parent a0ad43b80b
commit 920c52a5c8
1 changed files with 23 additions and 25 deletions
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48
miscutils/hdparm.c
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@ -1353,35 +1353,34 @@ static void read_big_block(/*int fd,*/ char *buf)
buf[i] &= 1; buf[i] &= 1;
} }
static unsigned long long dev_size_mb(/*int fd*/ void) static unsigned dev_size_mb(/*int fd*/ void)
{ {
union { union {
unsigned long long blksize64; unsigned long long blksize64;
unsigned blksize32; unsigned blksize32;
} u; } u;
if (0 == ioctl(fd, BLKGETSIZE64, &u.blksize64)) { // returns bytes if (0 == ioctl(fd, BLKGETSIZE64, &u.blksize64)) { // bytes
return u.blksize64 / (1024 * 1024); u.blksize64 /= (1024 * 1024);
} else {
xioctl(fd, BLKGETSIZE, &u.blksize32); // sectors
u.blksize64 = u.blksize32 / (2 * 1024);
} }
xioctl(fd, BLKGETSIZE, &u.blksize32); // returns sectors if (u.blksize64 > UINT_MAX)
return u.blksize32 / (2 * 1024); return UINT_MAX;
return u.blksize64;
} }
static void print_timing(unsigned long m, unsigned elapsed_us) static void print_timing(unsigned m, unsigned elapsed_us)
{ {
unsigned sec = elapsed_us / 1000000; unsigned sec = elapsed_us / 1000000;
unsigned hs = (elapsed_us % 1000000) / 10000; unsigned hs = (elapsed_us % 1000000) / 10000;
printf("%5lu MB in %u.%02u seconds = %lu kB/s\n", printf("%5u MB in %u.%02u seconds = %u kB/s\n",
m, sec, hs, m, sec, hs,
/* Trying to not overflow 32-bit arith in m * CONST /* + 1 prevents div-by-0 */
* by keeping CONST not so big. But elapsed_us / CONST2 (unsigned) ((unsigned long long)m * (1024 * 1000000) / (elapsed_us + 1))
* also should not introduce big errors. Currently, // ~= (m * 1024) / (elapsed_us / 1000000)
* 16000us is ~1.6% of 1 second.
* "+ 1" prevents div-by-0. */
(m * (1024 * 1000000 / (16*1024))) / (elapsed_us / (16*1024) + 1)
// ~= (m * 1024 * 1000000) / elapsed_us
// = (m * 1024) / (elapsed_us / 1000000)
// = kb / elapsed_sec // = kb / elapsed_sec
); );
} }
@ -1392,19 +1391,14 @@ static void do_time(int cache /*,int fd*/)
*/ */
{ {
unsigned max_iterations, iterations; unsigned max_iterations, iterations;
unsigned start; /* don't need to be long long */ unsigned start; /* doesn't need to be long long */
unsigned elapsed, elapsed2; unsigned elapsed, elapsed2;
unsigned long total_MB; unsigned total_MB;
char *buf = xmalloc(TIMING_BUF_BYTES); char *buf = xmalloc(TIMING_BUF_BYTES);
if (mlock(buf, TIMING_BUF_BYTES)) if (mlock(buf, TIMING_BUF_BYTES))
bb_perror_msg_and_die("mlock"); bb_perror_msg_and_die("mlock");
/* 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 * NB: *small* delay. User is expected to have a clue and to not run
* heavy io in parallel with measurements. */ * heavy io in parallel with measurements. */
@ -1422,10 +1416,14 @@ static void do_time(int cache /*,int fd*/)
/* Now do the timing */ /* Now do the timing */
iterations = 0; iterations = 0;
/* Max time to run (small for cache, avoids getting /* Max time to run (small for cache, avoids getting
* huge total_MB which can overlow on print_timing) */ * huge total_MB which can overlow unsigned type) */
elapsed2 = 510000; /* cache */ elapsed2 = 510000; /* cache */
if (!cache) max_iterations = UINT_MAX;
if (!cache) {
elapsed2 = 3000000; /* not cache */ elapsed2 = 3000000; /* not cache */
/* Don't want to read past the end! */
max_iterations = dev_size_mb() / TIMING_BUF_MB;
}
start = monotonic_us(); start = monotonic_us();
do { do {
if (cache) if (cache)
@ -1434,7 +1432,7 @@ static void do_time(int cache /*,int fd*/)
elapsed = (unsigned)monotonic_us() - start; elapsed = (unsigned)monotonic_us() - start;
++iterations; ++iterations;
} while (elapsed < elapsed2 && iterations < max_iterations); } while (elapsed < elapsed2 && iterations < max_iterations);
total_MB = (unsigned long)iterations * TIMING_BUF_MB; total_MB = iterations * TIMING_BUF_MB;
//printf(" elapsed:%u iterations:%u ", elapsed, iterations); //printf(" elapsed:%u iterations:%u ", elapsed, iterations);
if (cache) { if (cache) {
/* Cache: remove lseek() and monotonic_us() overheads /* Cache: remove lseek() and monotonic_us() overheads