X-Git-Url: https://git.kernel.dk/?a=blobdiff_plain;f=HOWTO;h=e4d3198e49559e0e085cd04e8adc2fa8495a424e;hb=b570e037a5bb8abf780b75e896a8dee336c2dd74;hp=dbbbfaa1d839e2d0bd73d91ceb83956c69f8e2c2;hpb=a6ab5391edbc87bdf1e5c0d218ccf7d8325a8c55;p=fio.git

diff --git a/HOWTO b/HOWTO
index dbbbfaa1..e4d3198e 100644
--- a/HOWTO
+++ b/HOWTO
@@ -2377,24 +2377,27 @@ Threads, processes and job synchronization
 
 	Set the I/O priority class. See man :manpage:`ionice(1)`.
 
-.. option:: cpumask=int
-
-	Set the CPU affinity of this job. The parameter given is a bit mask of
-	allowed CPUs 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
-	:manpage:`sched_setaffinity(2)`. This may not work on all supported
-	operating systems or kernel versions. This option doesn't work well for a
-	higher CPU count than what you can store in an integer mask, so it can only
-	control cpus 1-32. For boxes with larger CPU counts, use
-	:option:`cpus_allowed`.
-
 .. option:: cpus_allowed=str
 
 	Controls the same options as :option:`cpumask`, but accepts a textual
-	specification of the permitted CPUs instead. So to use CPUs 1 and 5 you
-	would specify ``cpus_allowed=1,5``. This option also allows a range of CPUs
-	to be specified -- say you wanted a binding to CPUs 1, 5, and 8 to 15, you
-	would set ``cpus_allowed=1,5,8-15``.
+	specification of the permitted CPUs instead and CPUs are indexed from 0. So
+	to use CPUs 0 and 5 you would specify ``cpus_allowed=0,5``. This option also
+	allows a range of CPUs to be specified -- say you wanted a binding to CPUs
+	0, 5, and 8 to 15, you would set ``cpus_allowed=0,5,8-15``.
+
+	On Windows, when ``cpus_allowed`` is unset only CPUs from fio's current
+	processor group will be used and affinity settings are inherited from the
+	system. An fio build configured to target Windows 7 makes options that set
+	CPUs processor group aware and values will set both the processor group
+	and a CPU from within that group. For example, on a system where processor
+	group 0 has 40 CPUs and processor group 1 has 32 CPUs, ``cpus_allowed``
+	values between 0 and 39 will bind CPUs from processor group 0 and
+	``cpus_allowed`` values between 40 and 71 will bind CPUs from processor
+	group 1. When using ``cpus_allowed_policy=shared`` all CPUs specified by a
+	single ``cpus_allowed`` option must be from the same processor group. For
+	Windows fio builds not built for Windows 7, CPUs will only be selected from
+	(and be relative to) whatever processor group fio happens to be running in
+	and CPUs from other processor groups cannot be used.
 
 .. option:: cpus_allowed_policy=str
 
@@ -2411,6 +2414,17 @@ Threads, processes and job synchronization
 	enough CPUs are given for the jobs listed, then fio will roundrobin the CPUs
 	in the set.
 
+.. option:: cpumask=int
+
+	Set the CPU affinity of this job. The parameter given is a bit mask of
+	allowed CPUs 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
+	:manpage:`sched_setaffinity(2)`. This may not work on all supported
+	operating systems or kernel versions. This option doesn't work well for a
+	higher CPU count than what you can store in an integer mask, so it can only
+	control cpus 1-32. For boxes with larger CPU counts, use
+	:option:`cpus_allowed`.
+
 .. option:: numa_cpu_nodes=str
 
 	Set this job running on specified NUMA nodes' CPUs. The arguments allow