Add cpus_allowed option

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 99cbaea37eb760dca27875eab9bcb8bd9def2292..0c243076ef65be503d7fc17d63ba4f7737182ec9 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -466,10 +466,16 @@ ratecycle=int     Average bandwidth for 'rate' and 'ratemin' over this number
                of milliseconds.
 
 cpumask=int    Set the CPU affinity of this job. The parameter given is a
-               bitmask of allowed CPU's the job may run on. See man
+               bitmask of allowed CPU's the job may run on. So if you want
+               the allowed CPUs to be 1 and 5, you would pass the decimal
+               value of (1 << 1 | 1 << 5), or 34. See man
                sched_setaffinity(2). This may not work on all supported
                operating systems or kernel versions.
 
+cpus_allowed=str Controls the same options as cpumask, but it allows a text
+               setting of the permitted CPUs instead. So to use CPUs 1 and
+               5, you would specify cpus_allowed=1,5.
+
 startdelay=int Start this job the specified number of seconds after fio
                has started. Only useful if the job file contains several
                jobs, and you want to delay starting some jobs to a certain