X-Git-Url: https://git.kernel.dk/?a=blobdiff_plain;f=HOWTO;h=8a4e2bde1b7b8a1bd85d1a56dba41eb7d23e1d26;hb=c2e9cc4d20c1db1c81276fdaadb56b8b0085d0d8;hp=662689ef304da064f677bdf5bf62b408e604abf3;hpb=a5e371a61c9e37a2389f7473d65e35b29dec1ccd;p=fio.git diff --git a/HOWTO b/HOWTO index 662689ef..8a4e2bde 100644 --- a/HOWTO +++ b/HOWTO @@ -320,7 +320,7 @@ rw=str Type of io pattern. Accepted values are: one by appending a ':' to the end of the string given. For a random read, it would look like 'rw=randread:8' for passing in an offset modifier with a value of 8. If the - postfix is used with a sequential IO pattern, then the value + suffix is used with a sequential IO pattern, then the value specified will be added to the generated offset for each IO. For instance, using rw=write:4k will skip 4k for every write. It turns sequential IO into sequential IO with holes. @@ -893,6 +893,11 @@ create_fsync=bool fsync the data file after creation. This is the create_on_open=bool Don't pre-setup the files for IO, just create open() when it's time to do IO to that file. +create_only=bool If true, fio will only run the setup phase of the job. + If files need to be laid out or updated on disk, only + that will be done. The actual job contents are not + executed. + pre_read=bool If this is given, files will be pre-read into memory before starting the given IO operation. This will also clear the 'invalidate' flag, since it is pointless to pre-read @@ -1107,8 +1112,8 @@ write_bw_log=str If given, write a bandwidth log of the jobs in this job file. Can be used to store data of the bandwidth of the jobs in their lifetime. The included fio_generate_plots script uses gnuplot to turn these text files into nice - graphs. See write_log_log for behaviour of given - filename. For this option, the postfix is _bw.log. + graphs. See write_lat_log for behaviour of given + filename. For this option, the suffix is _bw.log. write_lat_log=str Same as write_bw_log, except that this option stores io submission, completion, and total latencies instead. If no @@ -1150,12 +1155,6 @@ exec_postrun=str After the job completes, issue the command specified ioscheduler=str Attempt to switch the device hosting the file to the specified io scheduler before running. -cpuload=int If the job is a CPU cycle eater, attempt to use the specified - percentage of CPU cycles. - -cpuchunks=int If the job is a CPU cycle eater, split the load into - cycles of the given time. In microseconds. - disk_util=bool Generate disk utilization statistics, if the platform supports it. Defaults to on. @@ -1286,6 +1285,11 @@ that defines them is selected. enabled when polling for a minimum of 0 events (eg when iodepth_batch_complete=0). +[cpu] cpuload=int Attempt to use the specified percentage of CPU cycles. + +[cpu] cpuchunks=int Split the load into cycles of the given time. In + microseconds. + [netsplice] hostname=str [net] hostname=str The host name or IP address to use for TCP or UDP based IO. If the job is a TCP listener or UDP reader, the hostname is not @@ -1382,7 +1386,8 @@ runt= The runtime of that thread latency, since queue/complete is one operation there. This value can be in milliseconds or microseconds, fio will choose the most appropriate base and print that. In the example - above, milliseconds is the best scale. + above, milliseconds is the best scale. Note: in --minimal mode + latencies are always expressed in microseconds. clat= Completion latency. Same names as slat, this denotes the time from submission to completion of the io pieces. For sync io, clat will usually be equal (or very close) to 0, @@ -1447,6 +1452,9 @@ io_queue= Total time spent in the disk queue. util= The disk utilization. A value of 100% means we kept the disk busy constantly, 50% would be a disk idling half of the time. +It is also possible to get fio to dump the current output while it is +running, without terminating the job. To do that, send fio the USR1 signal. + 7.0 Terse output ---------------- @@ -1474,14 +1482,14 @@ Split up, the format is as follows: Completion latency: min, max, mean, deviation (usec) Completion latency percentiles: 20 fields (see below) Total latency: min, max, mean, deviation (usec) - Bw: min, max, aggregate percentage of total, mean, deviation + Bw (KB/s): min, max, aggregate percentage of total, mean, deviation WRITE status: Total IO (KB), bandwidth (KB/sec), IOPS, runtime (msec) Submission latency: min, max, mean, deviation (usec) Completion latency: min, max, mean, deviation (usec) Completion latency percentiles: 20 fields (see below) Total latency: min, max, mean, deviation (usec) - Bw: min, max, aggregate percentage of total, mean, deviation + Bw (KB/s): min, max, aggregate percentage of total, mean, deviation CPU usage: user, system, context switches, major faults, minor faults IO depths: <=1, 2, 4, 8, 16, 32, >=64 IO latencies microseconds: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000