I put a build harness around libav and gathered some profiling data. See:
bzr branch lp:~linaro-toolchain-dev/+junk/libav-suite
It includes a Makefile that builds a C only, h.264 only decoder and
two Creative Commons licensed videos to use as input.
README.rst has the basic commands for running ffmpeg and initial perf
results showing the hot functions. Dave, 20 % of the time is spent in
memcpy() so you might want to have a look.
The vectoriser has no effect. GCC 4.5 is ~17 % faster than 4.6. I'll
look into extracting and harnessing the functions themselves later
this week.
-- Michael
Hi,
is the Linaro toolchain (esp. gcc) useful on x86/x86_64, or is an
attempt to use the Linaro toolchain with such a target just asking for
trouble?
(No, I'm not secretly an Intel spy ;) Just trying to have some fun
with my desktop machine ;) )
ttyl
bero
The Linaro Toolchain Working Group is pleased to announce the release
of Linaro GDB 7.3.
Linaro GDB 7.3 2011.08 is the first release in the 7.3 series. Based
off the latest GDB 7.3, it includes a number of ARM-focused bug fixes.
This release includes all bug fixes from the latest Linaro GDB 7.2
release that were not already included in FSF GDB 7.3.
In addition, this release fixes:
* LP: #804401 [remote testsuite] Thread support
* LP: #804387 [remote testsuite] Shared library test problems
* LP: #804392 [remote testsuite] Rebuilt executables not copied
* LP: #804396 [remote testsuite] Spurious failures
The source tarball is available at:
https://launchpad.net/gdb-linaro/+milestone/7.3-2011.08
More information on Linaro GDB is available at:
https://launchpad.net/gdb-linaro
The Linaro Toolchain Working Group is pleased to announce the release
of Linaro QEMU 2011.08.
Linaro QEMU 2011.08 is the latest monthly release of qemu-linaro. Based
off upstream (trunk) QEMU, it includes a number of ARM-focused bug fixes
and enhancements.
This month's release is primarily minor improvements:
- Fixes LP:816791: ARMv6 cp15 barrier instructions now work
in linux-user mode as well as system mode
- Support for ARM1176JZF-S core has been added (thanks to
Jamie Iles <jamie(a)jamieiles.com>)
- Add workaround for kernel bug LP:727781 (which has resurfaced
in 3.0) to suppress warnings about bad-width omap i2c accesses
Plus of course new upstream fixes and improvements.
Performance:
When running qemu in system mode with an SD card image we have
determined that performance is best when the image is in writeback
caching mode. This significantly increases the performance of the SD
card (by factors of 10 or more). An example command line option is:
-drive if=sd,cache=writeback,file=my-sd-card.img
Note that cache=writeback may result in data not being written to
disk if the host system powers down unexpectedly (guest crashes
or powerdowns are not a problem).
Known issues:
- The beagle and beaglexm models still do not support USB networking
- There may be some problems with running multithreaded programs in
linux-user mode (LP:823902)
The source tarball is available at:
https://launchpad.net/qemu-linaro/+milestone/2011.08
Binary builds of this qemu-linaro release are being prepared and
will be available shortly for users of Ubuntu. Packages will be in
the linaro-maintainers tools ppa:
https://launchpad.net/~linaro-maintainers/+archive/tools/
More information on Linaro QEMU is available at:
https://launchpad.net/qemu-linaro
The Linaro Toolchain Working Group is pleased to announce the 2011.08
release of both Linaro GCC 4.6 and Linaro GCC 4.5.
Linaro GCC 4.6 2011.08 is the sixth release in the 4.6 series. Based
off the latest GCC 4.6.1+svn177703, it focuses on fixing bugs found
during the Android integration and in SMS. This is a quiet release
due to Linaro Connect.
Interesting changes include:
* Updates to 4.6.1+r177703
Fixes:
* LP: #736007 ICE immed_double_const at emit-rtl.c
* LP: #809768 ICE when compiling bionic's libm
* LP: #815777 Inconsistent packaging between tarball and root
directory names
Linaro GCC 4.5 2011.08 is the thirteenth release in the 4.5
series. Based off the latest GCC 4.5.3+svn177552, the release is
focused on maintenance.
Interesting changes in 4.5 include:
* Updates to 4.5.3+r177552
* Now builds for PowerPC
Fixes:
* LP: #736007 ICE immed_double_const at emit-rtl.c
* LP: #809768 ICE when compiling bionic's libm
* LP: #815435 ICE: insn does not satisfy its constraints
The source tarballs are available from:
https://launchpad.net/gcc-linaro/+milestone/4.6-2011.08https://launchpad.net/gcc-linaro/+milestone/4.5-2011.08
Downloads are available from the Linaro GCC page on Launchpad:
https://launchpad.net/gcc-linaro
Mailing list: http://lists.linaro.org/mailman/listinfo/linaro-toolchain
Bugs: https://bugs.launchpad.net/gcc-linaro/
Questions? https://ask.linaro.org/
Interested in commercial support? inquire at support(a)linaro.org
-- Michael
On Thu, Aug 18, 2011 at 4:16 AM, Richard Earnshaw
<Richard.Earnshaw(a)arm.com> wrote:
> I was just browsing libgmp this afternoon and noticed that it really
> could do with an overhaul to support recent ARM chips.
>
> The ARM code seems to have been written for StrongARM; which is now
> almost obsolete (for example, it loads from a cache line it is about to
> write to in order to pre-allocate the line in the cache).
>
> It doesn't support v4T interworking.
>
> It doesn't make any use of v5 or later instructions.
>
> There is some Thumb(1) code, but again it has no support for
> interworking, is pretty poor and limited in scope.
>
> I'm not sure overall how useful this is to gcc performance; the library
> is needed to build GCC, but I think it's mostly there to support libmpfr.
>
> Nevertheless, there are other apps out there that make use of this
> stuff, including some crypto code, IIRC.
I looked at using gmp as a benchmark some time ago. The assembly
version is twice as fast as the C version already, which is nice. I
assume NEON would be a big improvement as well.
I had a quick poke through the dependencies in Ubuntu and came up with
the following popular packages that use libgmp or libmpfr:
* guile
* python-crypto
* gch (Haskel)
* maxima
* darcs
Nothing earth shattering but probably worthwhile. I've registered:
https://blueprints.launchpad.net/linaro-toolchain-misc/+spec/improve-libgmp
so that we don't lose it.
-- Michael
Hi there. The 2011.08 release has been spun and is testing up well.
The 4.5 and 4.6 branches are now open so feel free to commit any
approved patches.
-- Michael
> . Would you be interested in adding a Firefox-based benchmark? As a large
> application it is a good testbed for LTO, FDO and other aggressive
> optimizations.
Sorry about the delayed response. I did notice your mail last week but
I was busy with our conference and then the first couple of days this
week have just disappeared with some internal training.
I would be interested in hearing how you get on with LTO and FDO on
ARM. Listening to Honza talking at the GCC unconference in London
about the memory usage for full LTO with trunk I did wonder what would
happen if we tried it on the ARM target to see what we got, but I
never managed to get around to trying anything there :) . We did look
at getting FDO working with Linaro GCC last cycle but there are still
a couple of issues with PGO in Linaro GCC 4.5.
With respect to LTO , the one problem we have currently is that the
Neon intrinsics aren't streamed out and streamed back in. So you might
have a few issues if your code uses arm_neon.h .
https://bugs.launchpad.net/gcc-linaro/+bug/823548 is an example of
this problem. This was fixed upstream and we probably just need to
backport that into our 4.6 tree. I've tried a backport this morning
and I think I have this right finally.
If you could do a build and a firefox benchmark run in about 30-60
minutes by all means please do let us know how you get on and what you
find. We've been steadily trying to improve the performance of the ARM
toolchain and the biggest improvements you'll notice will be with the
vectorizer but there will be other small improvements that you'll
notice in other general areas of code generation. We would be
interested in feedback about what can be done and to add to our queue
of things to look at and improve for the ARM port of GCC.
With respect to the images, Kiko's probably answered that bit.
cheers
Ramana
* GCC
Continued tracking down problems in my various broken patches. Fixed one
bug, investigated two more. Re-submitted the widening multiplies for
testing, and this time it returned with no problems. Yay, I can now
check it in next week.
Merged from upstream GCC 4.5. The launchpad import bug still exists
(although should not for much longer) so I had to ask on #launchpad to
get the imports done. Submitted the merged branch for testing.
Tried to merge GCC 4.6 similarly, but failed. Bzr just refused to play
ball, which was very frustrating. Michael Hope has now done the merge
instead.
* Other
On leave Wednesday and Friday.
* libauqntum - running the SMSed version on ARM machine did not show
significant improvement. Discussed it with Richard Sandiford.
Apparently in the SMS phase the instructions are of DI mode due to the
fact the loop contains 64 bit operations while they later been
generated as 32 bit operations. This makes SMS less accurate and I'm
now looking into a version which disables DI mode operations.
* Started to look at the potential of SMS on libav. Initial runs of
Richard's microbenchmarks with SMS show some regressions as well as
improvements that I'm looking at.
