Add section 9 to HOWTO table of contents.

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index d5fa98768735302bdfed61012744b8cd8ff7eca7..fbe8f7919988db293b921334268a424e887604fd 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -9,6 +9,7 @@ Table of contents
 6. Normal output
 7. Terse output
 8. Trace file format
 6. Normal output
 7. Terse output
 8. Trace file format

+9. CPU idleness profiling

 
 1.0 Overview and history
 ------------------------
 
 1.0 Overview and history
 ------------------------


@@ -353,6 +354,12 @@ kb_base=int        The base unit for a kilobyte. The defacto base is 2^10, 1024.
                ten unit instead, for obvious reasons. Allow values are
                1024 or 1000, with 1024 being the default.
 
                ten unit instead, for obvious reasons. Allow values are
                1024 or 1000, with 1024 being the default.
 

+unified_rw_reporting=bool      Fio normally reports statistics on a per
+               data direction basis, meaning that read, write, and trim are
+               accounted and reported separately. If this option is set,
+               the fio will sum the results and report them as "mixed"
+               instead.
+

 randrepeat=bool        For random IO workloads, seed the generator in a predictable
                way so that results are repeatable across repetitions.
 
 randrepeat=bool        For random IO workloads, seed the generator in a predictable
                way so that results are repeatable across repetitions.
 


@@ -769,7 +776,7 @@ random_generator=str        Fio supports the following engines for generating
                block sizes, not with workloads that use multiple block
                sizes. If used with such a workload, fio may read or write
                some blocks multiple times.
                block sizes, not with workloads that use multiple block
                sizes. If used with such a workload, fio may read or write
                some blocks multiple times.

-               
+

 nice=int       Run the job with the given nice value. See man nice(2).
 
 prio=int       Set the io priority value of this job. Linux limits us to
 nice=int       Run the job with the given nice value. See man nice(2).
 
 prio=int       Set the io priority value of this job. Linux limits us to


@@ -1396,6 +1403,9 @@ that defines them is selected.
 [netsplice] port=int
 [net] port=int The TCP or UDP port to bind to or connect to.
 
 [netsplice] port=int
 [net] port=int The TCP or UDP port to bind to or connect to.
 

+[netsplice] nodelay=bool
+[net] nodelay=bool     Set TCP_NODELAY on TCP connections.
+

 [netsplice] protocol=str
 [netsplice] proto=str
 [net] protocol=str
 [netsplice] protocol=str
 [netsplice] proto=str
 [net] protocol=str


@@ -1687,3 +1697,18 @@ write      Write 'length' bytes beginning from 'offset'
 sync       fsync() the file
 datasync   fdatasync() the file
 trim       trim the given file from the given 'offset' for 'length' bytes
 sync       fsync() the file
 datasync   fdatasync() the file
 trim       trim the given file from the given 'offset' for 'length' bytes

+
+
+9.0 CPU idleness profiling
+
+In some cases, we want to understand CPU overhead in a test. For example,
+we test patches for the specific goodness of whether they reduce CPU usage.
+fio implements a balloon approach to create a thread per CPU that runs at
+idle priority, meaning that it only runs when nobody else needs the cpu.
+By measuring the amount of work completed by the thread, idleness of each
+CPU can be derived accordingly.
+
+An unit work is defined as touching a full page of unsigned characters. Mean
+and standard deviation of time to complete an unit work is reported in "unit
+work" section. Options can be chosen to report detailed percpu idleness or
+overall system idleness by aggregating percpu stats.