Add necessary support to lowlevel-blt benchmark for benchmarking pixbuf and
rpixbuf fast paths. bench_composite function now checks for pixbuf string in
testname, and if that is detected, use same bits for src and mask images.
The source, mask and destination buffers are initialised to 0xCC just after
they are allocated. Between each benchmark, there are a pair of memcpys,
from the destination buffer to the source buffer and back again (there are
no explanatory comments, but presumably this is an effort to flush the
caches). However, it has an unintended consequence, which is to change the
contents of the buffers on entry to subsequent benchmarks. This means it is
not a fair test: for example, with over_n_8888 (featured in the following
patches) it reports L2 and even M tests as being faster than the L1 test,
because after the L1 test, the source buffer is filled with fully opaque
pixels, for which over_n_8888 has a shortcut.
The fix here is simply to reverse the order of the memcpys, so src and
destination are both filled with 0xCC on entry to all tests.
In particular this affects single-core ARMs (e.g. ARM11, Cortex-A8), which
are usually configured this way. For other CPUs, this should only add a
constant time, which will be cancelled out by the EXCLUDE_OVERHEAD runs.
The problems were caused by cachelines becoming permanently evicted from
the cache, because the code that was intended to pull them back in again on
each iteration assumed too long a cache line (for the L1 test) or failed to
read memory beyond the first pixel row (for the L2 test). Also, the reloading
of the source buffer was unnecessary.
These issues were identified by Siarhei in this post:
http://lists.freedesktop.org/archives/pixman/2013-January/002543.html
This adds two extra tests, src_n_8 and src_8_8, which I have been
using to benchmark my ARMv6 changes.
I'd also like to propose that it requires an exact test name as the
executable's argument, as achieved by this strstr to strcmp change.
Without this, it is impossible to only benchmark (for example)
add_8_8, add_n_8 or src_n_8, due to those also being substrings of
many other test names.
This patch has been generated by the following Coccinelle semantic patch:
// Use the ARRAY_LENGTH() macro when possible
//
// Replace open-coded array length computations with the
// ARRAY_LENGTH() macro
@@
type T;
T[] E;
@@
- (sizeof(E)/sizeof(T))
+ ARRAY_LENGTH (E)
All the tests are linked to libutil, hence it makes sence to always
include utils.h and reuse what it provides (config.h inclusion, access
to private pixman APIs, ARRAY_LENGTH, ...).
The next few commits will speed this up quite a bit.
Current output:
---
reference memcpy speed = 2217.5MB/s (554.4MP/s for 32bpp fills)
---
over_x888_8_0565 = L1: 54.67 L2: 54.01 M: 52.33 ( 18.88%) HT: 37.19 VT: 35.54 R: 29.40 RT: 13.63 ( 162Kops/s)
This test is a modified version of Siarhei's compositor throughput
benchmark. It's expanded with explicit reporting of memory bandwidth
consumption for the M-test, and with an additional 8x8-random test
intended to determine peak ops/sec capability. There are also quite a
lot more operations tested for.
