Revamp file locking

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 3d6b354b87b7df40f723c497ab82b1424cd287f6..3d9229338a11c9628f18d61a2a13e6cdc8b1c263 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -219,6 +219,25 @@ filename=str       Fio normally makes up a filename based on the job name,
 opendir=str    Tell fio to recursively add any file it can find in this
                directory and down the file system tree.
 
 opendir=str    Tell fio to recursively add any file it can find in this
                directory and down the file system tree.
 

+lockfile=str   Fio defaults to not doing any locking files before it does
+               IO to them. If a file or file descriptor is shared, fio
+               can serialize IO to that file to make the end result
+               consistent. This is usual for emulating real workloads that
+               share files. The lock modes are:
+
+                       none            No locking. The default.
+                       exclusive       Only one thread/process may do IO,
+                                       excluding all others.
+                       readwrite       Read-write locking on the file. Many
+                                       readers may access the file at the
+                                       same time, but writes get exclusive
+                                       access.
+
+               The option may be post-fixed with a lock batch number. If
+               set, then each thread/process may do that amount of IOs to
+               the file before giving up the lock. Since lock acqusition is
+               expensive, batching the lock/unlocks will speed up IO.
+

 readwrite=str
 rw=str         Type of io pattern. Accepted values are:
 
 readwrite=str
 rw=str         Type of io pattern. Accepted values are:
 


@@ -344,7 +363,7 @@ ioengine=str        Defines how the job issues io to the file. The following
 
                        psync   Basic pread(2) or pwrite(2) io.
 
 
                        psync   Basic pread(2) or pwrite(2) io.
 

-                       vsync   Basic readv(2) or writev(3) IO.
+                       vsync   Basic readv(2) or writev(2) IO.

 
                        libaio  Linux native asynchronous io.
 
 
                        libaio  Linux native asynchronous io.
 


@@ -383,7 +402,10 @@ ioengine=str       Defines how the job issues io to the file. The following
                                cycles according to the cpuload= and
                                cpucycle= options. Setting cpuload=85
                                will cause that job to do nothing but burn
                                cycles according to the cpuload= and
                                cpucycle= options. Setting cpuload=85
                                will cause that job to do nothing but burn

-                               85% of the CPU.
+                               85% of the CPU. In case of SMP machines,
+                               use numjobs=<no_of_cpu> to get desired CPU
+                               usage, as the cpuload only loads a single
+                               CPU at the desired rate.

 
                        guasi   The GUASI IO engine is the Generic Userspace
                                Asyncronous Syscall Interface approach
 
                        guasi   The GUASI IO engine is the Generic Userspace
                                Asyncronous Syscall Interface approach