X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=tools%2Fhist%2Ffiologparser_hist.py;h=778cc007601196aaa76803309314956f0ea75113;hp=58914275754f1dbffcccc5d1fafd27f4af647624;hb=d1f6fcadb7cb28a5e57a5e573395fe2deb3cfd7b;hpb=65a4d15c132de669223445791b141eb90267f761;ds=sidebyside diff --git a/tools/hist/fiologparser_hist.py b/tools/hist/fiologparser_hist.py index 58914275..778cc007 100755 --- a/tools/hist/fiologparser_hist.py +++ b/tools/hist/fiologparser_hist.py @@ -11,111 +11,6 @@ 4000, 39, 1152, 1546.962, 1545.785, 1627.192, 1640.019, 1691.204, 1744 ... - Notes: - - * end-times are calculated to be uniform increments of the --interval value given, - regardless of when histogram samples are reported. Of note: - - * Intervals with no samples are omitted. In the example above this means - "no statistics from 2 to 3 seconds" and "39 samples influenced the statistics - of the interval from 3 to 4 seconds". - - * Intervals with a single sample will have the same value for all statistics - - * The number of samples is unweighted, corresponding to the total number of samples - which have any effect whatsoever on the interval. - - * Min statistics are computed using value of the lower boundary of the first bin - (in increasing bin order) with non-zero samples in it. Similarly for max, - we take the upper boundary of the last bin with non-zero samples in it. - This is semantically identical to taking the 0th and 100th percentiles with a - 50% bin-width buffer (because percentiles are computed using mid-points of - the bins). This enforces the following nice properties: - - * min <= 50th <= 90th <= 95th <= 99th <= max - - * min and max are strict lower and upper bounds on the actual - min / max seen by fio (and reported in *_clat.* with averaging turned off). - - * Average statistics use a standard weighted arithmetic mean. - - * Percentile statistics are computed using the weighted percentile method as - described here: https://en.wikipedia.org/wiki/Percentile#Weighted_percentile - See weights() method for details on how weights are computed for individual - samples. In process_interval() we further multiply by the height of each bin - to get weighted histograms. - - * We convert files given on the command line, assumed to be fio histogram files, - An individual histogram file can contain the - histograms for multiple different r/w directions (notably when --rw=randrw). This - is accounted for by tracking each r/w direction separately. In the statistics - reported we ultimately merge *all* histograms (regardless of r/w direction). - - * The value of *_GROUP_NR in stat.h (and *_BITS) determines how many latency bins - fio outputs when histogramming is enabled. Namely for the current default of - GROUP_NR=19, we get 1,216 bins with a maximum latency of approximately 17 - seconds. For certain applications this may not be sufficient. With GROUP_NR=24 - we have 1,536 bins, giving us a maximum latency of 541 seconds (~ 9 minutes). If - you expect your application to experience latencies greater than 17 seconds, - you will need to recompile fio with a larger GROUP_NR, e.g. with: - - sed -i.bak 's/^#define FIO_IO_U_PLAT_GROUP_NR 19\n/#define FIO_IO_U_PLAT_GROUP_NR 24/g' stat.h - make fio - - Quick reference table for the max latency corresponding to a sampling of - values for GROUP_NR: - - GROUP_NR | # bins | max latency bin value - 19 | 1216 | 16.9 sec - 20 | 1280 | 33.8 sec - 21 | 1344 | 67.6 sec - 22 | 1408 | 2 min, 15 sec - 23 | 1472 | 4 min, 32 sec - 24 | 1536 | 9 min, 4 sec - 25 | 1600 | 18 min, 8 sec - 26 | 1664 | 36 min, 16 sec - - * At present this program automatically detects the number of histogram bins in - the log files, and adjusts the bin latency values accordingly. In particular if - you use the --log_hist_coarseness parameter of fio, you get output files with - a number of bins according to the following table (note that the first - row is identical to the table above): - - coarse \ GROUP_NR - 19 20 21 22 23 24 25 26 - ------------------------------------------------------- - 0 [[ 1216, 1280, 1344, 1408, 1472, 1536, 1600, 1664], - 1 [ 608, 640, 672, 704, 736, 768, 800, 832], - 2 [ 304, 320, 336, 352, 368, 384, 400, 416], - 3 [ 152, 160, 168, 176, 184, 192, 200, 208], - 4 [ 76, 80, 84, 88, 92, 96, 100, 104], - 5 [ 38, 40, 42, 44, 46, 48, 50, 52], - 6 [ 19, 20, 21, 22, 23, 24, 25, 26], - 7 [ N/A, 10, N/A, 11, N/A, 12, N/A, 13], - 8 [ N/A, 5, N/A, N/A, N/A, 6, N/A, N/A]] - - For other values of GROUP_NR and coarseness, this table can be computed like this: - - bins = [1216,1280,1344,1408,1472,1536,1600,1664] - max_coarse = 8 - fncn = lambda z: list(map(lambda x: z/2**x if z % 2**x == 0 else nan, range(max_coarse + 1))) - np.transpose(list(map(fncn, bins))) - - Also note that you can achieve the same downsampling / log file size reduction - by pre-processing (before inputting into this script) with half_bins.py. - - * If you have not adjusted GROUP_NR for your (high latency) application, then you - will see the percentiles computed by this tool max out at the max latency bin - value as in the first table above, and in this plot (where GROUP_NR=19 and thus we see - a max latency of ~16.7 seconds in the red line): - - https://www.cronburg.com/fio/max_latency_bin_value_bug.png - - * Motivation for, design decisions, and the implementation process are - described in further detail here: - - https://www.cronburg.com/fio/cloud-latency-problem-measurement/ - @author Karl Cronburg """ import os @@ -216,7 +111,7 @@ def histogram_generator(ctx, fps, sz): rdrs[fp] = pandas.read_csv(fp, dtype=int, header=None, chunksize=sz) except ValueError as e: if e.message == 'No columns to parse from file': - if not ctx.nowarn: sys.stderr.write("WARNING: Empty input file encountered.\n") + if ctx.warn: sys.stderr.write("WARNING: Empty input file encountered.\n") rdrs[fp] = None else: raise(e) @@ -441,11 +336,11 @@ if __name__ == '__main__': type=int, help='number of decimal places to print floats to') - arg('--nowarn', - dest='nowarn', - action='store_false', - default=True, - help='do not print any warning messages to stderr') + arg('--warn', + dest='warn', + action='store_true', + default=False, + help='print warning messages to stderr') arg('--group_nr', default=19,