Add --parse-only command line option

Sometimes it's useful just being able to verify whether a job
config is valid or not, without actually starting any jobs.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Fix rate iops with ramp time

When the ramp time is over, fio resets the ->io_issues[]
counters, but not the rwmix counters. This causes a problem
for mixed read/write workloads that are rate limited and
include a ramp time.

Fix it by resetting rwmix_issues with the regular issues.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Fix skewed latencies for rate IOPS

- when -rate_iops is specified, FIO periodically calls usleep() to limit IOPS

- Before usleep(), FIO always wait until the completion of all pending I/O

- For all I/O completions, FIO shows erroneous behavior of logging their
  latency, with that of the longest latency IO sample.

- w/ QD=8/ mixed R:W=33:66, up to 7 samples may get false latency log when
  waiting all I/O completions => False report of latency distribution

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Improve LFSR implementation

Changes:

1. Use Galois LFSR instead of Fibonacci LFSR.
2. Use XNOR gates instead of XOR gates.
3. Add tap sizes for LFSRs ranging from 3-bits to 15-bits.
4. Add spin parameter.

Rationale:

1. Fibonacci LFSRs have the following drawbacks:

   a. Their next state can not be computed in one cycle, since the input
      bit must be propagated serially through the XOR gates. Galois
	  LFSRs however, can be computed instantly with XOR-masks.

   b. Their state changes cannot be considered "irregular", even by I/O
      standards. Actually, if the current state of an n-bit LFSR is x,
	  then the next will either be (x >> 1) or (2^n + (x >> 1)). Galois
	  LFSRs have instead their XOR gates interleaved with their bits,
	  which means that the inner bits are changed as well, besides of
	  the shifting. If the number of taps is z, this means that the
	  different outcomes are 2^(z + 1).

2. An LFSR with XOR gates has the all-zeroes state as illegal. Since
   zero is valid for most I/O operations, it would be more intuitive to
   use XNOR gates, that have as the all-ones state as illegal.

3. Allow smaller I/O benchmarks to use LFSRs.

4. The spin parameter follows the same rationale as in 1b. To make the
   LFSR outcome "appear" less predictable, we can spin internally the
   LFSR state and produce the i-th number. To understand the spin
   parameter, consider the following state sequence of a 3-bit LFSR:

                             0, 2, 3, 5, 6, 1, 4
   Same LFSR, spin value 2:  0, 3, 6, 4, 2, 5, 1
   But what is the benefit from using spin? Well, the benefits are
   two-fold:

   a. For the same I/O size, we can create a different I/O sequences.

   b. Following the rationale of 1b, we can have more variable outcomes.
      If the spin value is "i" and the taps are "z", the number of
	  different outcomes become i * 2^(z + 1).

Signed-off-by: Alex Pyrgiotis <apyrgio@grnet.gr>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a simple test for LFSR generator

Adds a simple test suite to check the speed of the LFSR
generator and verify its results. Just run:

    make t/lfsr-test
    ./t/lfsr-test

to compile the test suite and print its usage

Signed-off-by: Alex Pyrgiotis <apyrgio@grnet.gr>

 create mode 100644 t/lfsr-test.c
Signed-off-by: Jens Axboe <axboe@kernel.dk>
lfsr: indent table

Signed-off-by: Jens Axboe <axboe@kernel.dk>
lfsr: Fix spin related bug

On the previous patch on cycle detection, we would incremet spin value
when:

    num_vals % cycle_length == 0

which would evaluate always to true for the first iteration since we
start with num_vals = 0. Only one corner-case is affected by this bug
and this patch should fix it.

Signed-off-by: Alex Pyrgiotis <apyrgio@grnet.gr>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remove config-host.h on clean.

Signed-off-by: Oleg Matcovschi <olegmatcovsky@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Conditionally include <sys/shm.h> based on OS support. Define missing MAP_HUGETLB for Android.

Signed-off-by: Oleg Matcovschi <olegmatcovsky@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
lfsr: fix verification and spin bugs

Changes:

1. Verification now works properly and reports for which value it fails
2. Fix a mishandling of spin incrementation which led to multiple
calculation of the same values

Signed-off-by: Alex Pyrgiotis <apyrgio@grnet.gr>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Android: add ioprio support

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Make test for gnuplot work with empty strings.

When I launch fio_generate_plots on a system where gnuplot is not installed I
get this error :

$ fio_generate_plots test
Making bw logs
/usr/bin/fio_generate_plots: 42: /usr/bin/fio_generate_plots: -: not found

That's because the test checking whether gnuplot is installed is failing
because of an empty variable :
GNUPLOT=$(which gnuplot)
if [ ! -x $GNUPLOT ]; then
        echo You need gnuplot installed to generate graphs
        exit 1
fi

Indeed the command "test -x" is exiting with code 0.

To correct this we should enclose the variable with quotes :
if [ ! -x "$GNUPLOT" ]; then

Then the script is going into the test properly :
$ fio_generate_plots test
You need gnuplot installed to generate graphs

I copied problem description by Hervé from the Debian bug report below.

Fixes:
Bug#700580: /usr/bin/fio_generate_plots: -: not found
http://bugs.debian.org/700580

Reported-By: Hervé Werner <hwerner@score-md.com>
Tested-By: Hervé Werner <hwerner@score-md.com>
Tested-By: Martin Steigerwald <ms@teamix.de>

Signed-off-by: Jens Axboe <axboe@kernel.dk>
android: fix compile by not defining FIO_NO_HAVE_SHM_H twice

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Propagate target OS from configure to Makefile

Propagate target OS from configure to Makefile (CONFIG_TARGET_OS) to avoid
duplicating the check in Makefile.  Also allow CROSS_COMPILE for the toolchain
prefix, which is common (e.g. Linux).

Signed-off-by: Aaron Carroll <aaronc@cse.unsw.edu.au>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
configure: compile-time word size detection

Signed-off-by: Aaron Carroll <aaronc@cse.unsw.edu.au>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
configure: endianness check for cross compile

 - Add a cross compile check: assume yes if we can't run a test binary
 - If cross compiling, revert to a compile-time endianess check. This tries
   a few possible ways to detect big endian, but otherwise assumes little. We
   rely on the run-time check to save us if the build-time check is wrong.

Signed-off-by: Aaron Carroll <aaronc@cse.unsw.edu.au>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Android: remove static Android configuration

Android can now be configured dynamically, so remove the static config.
For this we need to modify the socklen_t check #includes which appear to
be wrong anyway.

Signed-off-by: Aaron Carroll <aaronc@cse.unsw.edu.au>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Fixup commit error in 56c796

I hand-fondled it, forgot to revert.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
A few ULL -> uint64_t conversions

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Fix re-run issue when job size is set to "unknown"

Assert that td->o.size is valid before comparing the IO amount
we did to it. This prevents re-running a job because we think
there's more work to do. But if we haven't set ->o.size to a
valid value, then that must not determine whether to re-run
the loop or not.

Signed-off-by: Jens Axboe <axboe@kernel.dk>