diff options
Diffstat (limited to 'miscutils')
| -rw-r--r-- | miscutils/hdparm.c | 135 |
1 files changed, 69 insertions, 66 deletions
diff --git a/miscutils/hdparm.c b/miscutils/hdparm.c index 1e34f4f..eb4991e 100644 --- a/miscutils/hdparm.c +++ b/miscutils/hdparm.c @@ -1023,11 +1023,14 @@ static void identify (uint16_t *id_supplied, const char *devname) #define VERSION "v5.4" -#undef DO_FLUSHCACHE /* under construction: force cache flush on -W0 */ -#define TIMING_BUF_MB 2 +#define TIMING_MB 64 +#define TIMING_BUF_MB 1 #define TIMING_BUF_BYTES (TIMING_BUF_MB * 1024 * 1024) +#define TIMING_BUF_COUNT (timing_MB / TIMING_BUF_MB) #define BUFCACHE_FACTOR 2 +#undef DO_FLUSHCACHE /* under construction: force cache flush on -W0 */ + static int verbose = 0, get_identity = 0, get_geom = 0, noisy = 1, quiet = 0; static int flagcount = 0, do_flush = 0, is_scsi_hd = 0, is_xt_hd = 0; static int do_ctimings, do_timings = 0; @@ -1303,13 +1306,15 @@ static int read_big_block (int fd, char *buf) return 0; } -static void time_cache (int fd) +static double correction = 0.0; + +void time_cache (int fd) { + int i; char *buf; struct itimerval e1, e2; int shmid; - double elapsed, elapsed2; - unsigned int iterations, total_MB; + int timing_MB = TIMING_MB; if ((shmid = shmget(IPC_PRIVATE, TIMING_BUF_BYTES, 0600)) == -1) { bb_perror_msg ("could not allocate sharedmem buf"); @@ -1332,7 +1337,12 @@ static void time_cache (int fd) sync(); sleep(3); - /* + /* Calculate a correction factor for the basic + * overhead of doing a read() from the buffer cache. + * To do this, we read the data once to "cache it" and + * to force full preallocation of our timing buffer, + * and then we re-read it 10 times while timing it. + * * getitimer() is used rather than gettimeofday() because * it is much more consistent (on my machine, at least). */ @@ -1346,42 +1356,34 @@ static void time_cache (int fd) sync(); sleep(1); - /* Now do the timing */ - iterations = 0; + /* Time re-reading from the buffer-cache */ getitimer(ITIMER_REAL, &e1); - do { - ++iterations; - if (seek_to_zero (fd) || read_big_block (fd, buf)) - goto quit; - getitimer(ITIMER_REAL, &e2); - elapsed = (e1.it_value.tv_sec - e2.it_value.tv_sec) - + ((e1.it_value.tv_usec - e2.it_value.tv_usec) / 1000000.0); - } while (elapsed < 2.0); - total_MB = iterations * TIMING_BUF_MB; - - elapsed = (e1.it_value.tv_sec - e2.it_value.tv_sec) + for (i = (BUFCACHE_FACTOR * TIMING_BUF_COUNT) ; i > 0; --i) { + if (seek_to_zero (fd)) goto quit; + if (read_big_block (fd, buf)) goto quit; + } + getitimer(ITIMER_REAL, &e2); + correction = (e1.it_value.tv_sec - e2.it_value.tv_sec) + ((e1.it_value.tv_usec - e2.it_value.tv_usec) / 1000000.0); - /* Now remove the lseek() and getitimer() overheads from the elapsed time */ + /* Now remove the lseek() from the correction factor */ getitimer(ITIMER_REAL, &e1); - do { - if (seek_to_zero (fd)) - goto quit; - getitimer(ITIMER_REAL, &e2); - elapsed2 = (e1.it_value.tv_sec - e2.it_value.tv_sec) - + ((e1.it_value.tv_usec - e2.it_value.tv_usec) / 1000000.0); - } while (--iterations); - - elapsed -= elapsed2; - - if ((BUFCACHE_FACTOR * total_MB) >= elapsed) /* more than 1MB/s */ - printf("%3u MB in %5.2f seconds = %6.2f MB/sec\n", - (BUFCACHE_FACTOR * total_MB), elapsed, - (BUFCACHE_FACTOR * total_MB) / elapsed); + for (i = (BUFCACHE_FACTOR * TIMING_BUF_COUNT) ; i > 0; --i) { + if (seek_to_zero (fd)) goto quit; + } + getitimer(ITIMER_REAL, &e2); + correction -= (e1.it_value.tv_sec - e2.it_value.tv_sec) + + ((e1.it_value.tv_usec - e2.it_value.tv_usec) / 1000000.0); + + if ((BUFCACHE_FACTOR * timing_MB) >= correction) /* more than 1MB/s */ + printf("%2d MB in %5.2f seconds =%6.2f MB/sec\n", + (BUFCACHE_FACTOR * timing_MB), correction, + (BUFCACHE_FACTOR * timing_MB) / correction); else - printf("%3u MB in %5.2f seconds = %6.2f kB/sec\n", - (BUFCACHE_FACTOR * total_MB), elapsed, - (BUFCACHE_FACTOR * total_MB) / elapsed * 1024); + printf("%2d MB in %5.2f seconds =%6.2f kB/sec\n", + (BUFCACHE_FACTOR * timing_MB), correction, + (BUFCACHE_FACTOR * timing_MB) / correction * 1024); + correction /= BUFCACHE_FACTOR; flush_buffer_cache(fd); sleep(1); @@ -1390,24 +1392,14 @@ quit: bb_perror_msg ("could not detach sharedmem buf"); } -static void time_device (int fd) +void time_device (int fd) { + int i; char *buf; double elapsed; struct itimerval e1, e2; int shmid; - unsigned int max_iterations = 1024, total_MB, iterations; - static long parm; - - // - // get device size - // - if (do_ctimings || do_timings) { - if (ioctl(fd, BLKGETSIZE, &parm)) - bb_perror_msg(" BLKGETSIZE failed"); - else - max_iterations = parm / (2 * 1024) / TIMING_BUF_MB; - } + int timing_MB = TIMING_MB; if ((shmid = shmget(IPC_PRIVATE, TIMING_BUF_BYTES, 0600)) == -1) { bb_perror_msg ("could not allocate sharedmem buf"); @@ -1440,24 +1432,35 @@ static void time_device (int fd) setitimer(ITIMER_REAL, &(struct itimerval){{1000,0},{1000,0}}, NULL); /* Now do the timings for real */ - iterations = 0; getitimer(ITIMER_REAL, &e1); - do { - ++iterations; - if (read_big_block (fd, buf)) - goto quit; - getitimer(ITIMER_REAL, &e2); - elapsed = (e1.it_value.tv_sec - e2.it_value.tv_sec) - + ((e1.it_value.tv_usec - e2.it_value.tv_usec) / 1000000.0); - } while (elapsed < 3.0 && iterations < max_iterations); - - total_MB = iterations * TIMING_BUF_MB; - if ((total_MB / elapsed) > 1.0) /* more than 1MB/s */ - printf("%3u MB in %5.2f seconds = %6.2f MB/sec\n", - total_MB, elapsed, total_MB / elapsed); + for (i = TIMING_BUF_COUNT; i > 0; --i) { + if (read_big_block (fd, buf)) goto quit; + } + getitimer(ITIMER_REAL, &e2); + + elapsed = (e1.it_value.tv_sec - e2.it_value.tv_sec) + + ((e1.it_value.tv_usec - e2.it_value.tv_usec) / 1000000.0); + if (timing_MB >= elapsed) /* more than 1MB/s */ + printf("%2d MB in %5.2f seconds =%6.2f MB/sec\n", + timing_MB, elapsed, timing_MB / elapsed); else - printf("%3u MB in %5.2f seconds = %6.2f kB/sec\n", - total_MB, elapsed, total_MB / elapsed * 1024); + printf("%2d MB in %5.2f seconds =%6.2f kB/sec\n", + timing_MB, elapsed, timing_MB / elapsed * 1024); + + if (elapsed <= (correction * 2)) + printf("Hmm.. suspicious results: probably not enough free memory for a proper test.\n"); +#if 0 /* the "estimate" is just plain wrong for many systems.. */ + else if (correction != 0.0) { + printf(" Estimating raw driver speed: "); + elapsed -= correction; + if (timing_MB >= elapsed) /* more than 1MB/s */ + printf("%2d MB in %5.2f seconds =%6.2f MB/sec\n", + timing_MB, elapsed, timing_MB / elapsed); + else + printf("%2d MB in %5.2f seconds =%6.2f kB/sec\n", + timing_MB, elapsed, timing_MB / elapsed * 1024); + } +#endif quit: if (-1 == shmdt(buf)) bb_perror_msg ("could not detach sharedmem buf"); |