Add support for async IO verification offload

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 3107d3a15e6b4488dcd8626264b791d078459d1e..55662d34bae7d7cc2ed46a6b87d2a5fa971568ee 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -741,7 +741,10 @@ create_on_open=bool        Don't pre-setup the files for IO, just create open()
 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
-               and then drop the cache.
+               and then drop the cache. This will only work for IO engines
+               that are seekable, since they allow you to read the same data
+               multiple times. Thus it will not work on eg network or splice
+               IO.
 
 unlink=bool    Unlink the job files when done. Not the default, as repeated
                runs of that job would then waste time recreating the file
@@ -824,6 +827,16 @@ verify_fatal=bool  Normally fio will keep checking the entire contents
                before quitting on a block verification failure. If this
                option is set, fio will exit the job on the first observed
                failure.
+
+verify_async=int       Fio will normally verify IO inline from the submitting
+               thread. This option takes an integer describing how many
+               async offload threads to create for IO verification instead,
+               causing fio to offload the duty of verifying IO contents
+               to one or more separate threads.
+
+verify_async_cpus=str  Tell fio to set the given CPU affinity on the
+               async IO verification threads. See cpus_allowed for the
+               format used.
                
 stonewall      Wait for preceeding jobs in the job file to exit, before
                starting this one. Can be used to insert serialization