== String routines ==
* Trying to understand my strlen behaviour that Michael identified
- Found lots of ways of making the faster case slower, but none of making
the slower case faster!
- Perf not being available on Panda (bug 702999/843628) made it
difficult to
dig down
* Fixing standards corner cases for strchr/memchr
- input match needs to be truncated to char (fixes bug 842258 & 791274)
* Tidying up formatting for cortex-strings release
* Looking at eglibc integration again
- getting confused by what has to happen in config.sub and how
other users of it
cope with triplets like armv7 even though it's not in config.sub
== QEMU ==
* Testing Peter's QEMU release
- All good
- Lost a few hours due to the broken version of l-i-f-ui in Oneiric
- PPA version works OK
* A little bit of perf profiling
== Other ==
* Managed to get hold of a nice fast build machine
== GDB ==
* Worked on hardware watchpoint support for gdbserver.
== GCC ==
* Analyzed root cause of three more ICEs when building Linux
kernel with mainline GCC (reported by Arnd):
PR target/50305: Inline asm reload failure when building Linux kernel
PR middle-end/50307: SSA checking ICE when building Linux kernel
PR tree-optimization/50318: ICE optimizing widening
multiply-and-accumulate
* Implemented proposed fix for PR target/50305 and posted for review.
== Misc ==
* Installed updated FPGA bitfiles on my Versatile Express and verified
that network stability issues (LP #673820) are now fixed.
* Booked Linaro Connect Q4.11 travel.
Mit freundlichen Gruessen / Best Regards
Ulrich Weigand
--
Dr. Ulrich Weigand | Phone: +49-7031/16-3727
STSM, GNU compiler and toolchain for Linux on System z and Cell/B.E.
IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Martin Jetter | Geschäftsführung: Dirk
Wittkopp
Sitz der Gesellschaft: Böblingen | Registergericht: Amtsgericht
Stuttgart, HRB 243294
RAG:
Red:
Amber:
Green: overrunning OMAP3 upstreaming work (mostly) replanned
Current Milestones:
|| || Planned || Estimate || Actual ||
||qemu-linaro 2011-09 || 2011-09-15 || 2011-09-15 || ||
Historical Milestones:
||qemu-linaro 2011-04 || 2011-04-21 || 2011-04-21 || 2011-04-21 ||
||qemu-linaro 2011-05 || 2011-05-19 || 2011-05-19 || n/a ||
||close out 1105 blueprints || 2011-05-28 || 2011-05-28 || 2011-05-19 ||
||complete 1111 planning || 2011-05-28 || 2011-05-28 || 2011-05-27 ||
||qemu-linaro-2011-06 || 2011-06-16 || 2011-06-16 || 2011-06-16 ||
||qemu-linaro-2011-07 || 2011-07-21 || 2011-07-21 || 2011-07-21 ||
||qemu-linaro 2011-08 || 2011-08-18 || 2011-08-18 || 2011-08-18 ||
== upstream-omap3-patches ==
* more reshuffling of patches and dropping of unnecessary changes (eg
code reformatting)
* we're going to divide this blueprint into four, each of which has a
reasonably clearly defined submilestone and an estimated 3
engineering weeks of work in it
* in order to not have work on this completely push out other items on
the schedule, we're going to limit work done on this to 2 or 3 days
each week
* still todo: actually split the blueprint, set dates for
submilestones, check that other blueprints fit reasonably in the
other half-week
== linaro-qemu-11.11 ==
* built a pre-release tarball and tested it -- looks good for next
week's release
* investigated whether we can reinstate the firmware blobs in our
releases (bringing us back into line with upstream) -- should be
possible but need to go through the license approval process since
some are GPLv3
== a15-system-mode-planning ==
* starting to see some (gentle) pressure for A15 support
* thinking about what we should do here; my current opinion is that
QEMU should implement an "A15 without virtualization or LPAE" -- we
have Linux kernels that will boot on this, and it is essentially
what an A15-on-A15 hw virt guest would see. The device work will be
needed for KVM anyway. Need to write this up.
== other ==
* submitted TSC licensing request to add the firmware blobs back into
our qemu-linaro tarballs, in line with how upstream do releases
* I need to track better how much time I'm spending on things like code
review on qemu-devel, minor bug fixing and other things that aren't
blueprints
* all holiday to the end of the year now booked (see below)
Current qemu patch status is tracked here:
https://wiki.linaro.org/PeterMaydell/QemuPatchStatus
Absences (to end of year):
Sep 19, Sep 29-Oct 07, Oct 17, Nov 21, Dec 15-Jan 03: leave
Oct 30-Nov 04: Linaro Connect Q4.11
Hi,
* I've been setting up a new system because the old laptop died
* finished the initial port of libunwind for Android on ARM
* changed debuggerd to make use of libunwind to unwind the stack of
crashing applications
* it works and the output looks great :)
* I plan to document these things in the wiki by next week
Regards
Ken
Just as an FYI, I've added these loops to the libav microbenchmarks
avg-h264-chroma-mc8-8.txt
avg-pixels8-8.txt
ff-h264-idct-add-8-8.txt
ff-put-pixels8x16-8.txt
h264-loop-filter-luma-8.txt
idct-internal-8.txt
put-h264-chroma-mc8-8.txt
put-h264-qpel8-h-lowpass-8.txt
put-h264-qpel8-hv-lowpass-8.txt
put-h264-qpel8-v-lowpass-8.txt
based on Michael's h264 profile. These loops:
decode_residual
ff_h264_decode_mb_cavlc
fill_decode_caches
aren't really the kind of thing that the microbenchmark is designed for;
running the whole h264 benchmark is probably a better test. Some of the
functions in the profile just consist of two copies of a simpler loop,
one after the other, so for those I just used the simpler loop.
Usual microbenchmark caveats apply.
Richard
Hi,
* merged vector over-promotion patch to linaro-gcc-4.6
* committed upstream the change of the default vector size for NEON
* continued working on widening shifts
Ira
Hi Dave. I've been hacking away and have checked in a couple of
benchmarking and plotting scripts to lp:cortex-strings. The current
results are at:
http://people.linaro.org/~michaelh/incoming/strings-performance/
All are done on an A9. The results are very incomplete due to how
long things take to run. I'll leave ursa3 doing these over the
weekend which should flesh this out for the other routines.
Your new memcpy() is looking good as well - as fast as GLIBC.
-- Michael
While out benchmarking today, I ran across code similar to this:
int *a;
int *b;
int *c;
const int ad[320];
const int bd[320];
const int cd[320];
void fill()
{
for (int i = 0; i < 320; i++)
{
a[i] = ad[i];
b[i] = bd[i];
c[i] = cd[i];
}
}
I was surprised and happy to see the vectoriser kick in for the copy.
The inner loop looks like:
add r5, r3, ip
adds r4, r3, r7
vldmia r2!, {d16-d17}
vldmia r1!, {d18-d19}
adds r0, r3, r6
vst1.32 {q9}, [r5]
vst1.32 {q8}, [r4]
vldmia r3, {d16-d17}
adds r3, r3, #16
cmp r3, r8
vst1.32 {q8}, [r0]
bne .L3
so r3 is the loop variable and {ip,r7} are the offsets from r3 to the
destination pointers. Adding a __restrict doesn't change the code.
Richard, will your auto-inc/dec changes combine the final vldmia r3,
add r3 into a vldmia r3! ?
Changing the int *a into in-file arrays like int a[320] gives:
vldmia r0!, {d16-d17}
vldmia r5!, {d18-d19}
vstmia r4!, {d18-d19}
vstmia r1!, {d16-d17}
vldmia r2!, {d16-d17}
vstmia r3!, {d16-d17}
cmp r3, r6
bne .L2
Marking them as extern int a[320] goes back to the first form.
Can we always use the second form? What optimisation is preventing it?
-- Michael
On Fri, Sep 2, 2011 at 4:51 AM, David Gilbert <david.gilbert(a)linaro.org> wrote:
> Hi Michael,
> I've just committed a pair of memcpy's into src/linaro-a9 - memcpy.S
> that is armv7
> and memcpy-hybrid.S that is a Neon hybrid which uses neon for non-aligned cases
> and for large (128K or larger) copies. I've also (accidentally)
> wired the memcpy-hybrid
> one into the Makefile.am (I wasn't sure what the right way to do this
> was - the neon_sources
> seemed a good place for it, but there is nothing currently in there
> that turns off the non-neon
> version).
>
> I'd be interested in seeing the results for both; I've got a bit of
> a soft spot for the hybrid
> solution.
>
> On the memset, yes the 'and' that you added is fine - but I started
> having a play and have
> some performance results (on -t 128) that I don't really understand:
>
>
> 1) and r1,#0xff
> orr r1,r1,r1,lsl#8
> orr r1,r1,r1,lsl#16
>
> That's your solution - and fastest at somewhere around 2270MB/s for
> me - by the TRM I reckon
> that should be 3 cycles.
>
> 2) lsls r1,#24
> orr r1,r1,r1,lsr#8
> orr r1,r1,r1,lsr#16
>
> lsl isn't explicitly listed in the TRM, so I assumed that was the
> same as a move with a constant
> shift, which my reading is that it's a single cycle; and the lsls is 2
> bytes - so you would think
> that should be as fast as yours but 2 bytes smaller - except it's
> reliably down at 2228MB/s - so
> it is slower.
>
> 3) Thinking it was an alignment issue I tried adding a mov r5,r1 to
> the front of that, and got 2248MB/s -
> so being faster with an extra instruction it probably was an alignment issue?
>
> 4) I also tried a pair of bfi's:
> bfi r1,r1, #8, #8
> bfi r1,r1, #16, #16
>
> That came out at 2228MB/s - and is 4 cycles by the book.
Unfortunately you can't tell the performance from the latency.
Attached is a micro benchmark that has the three different versions
(and, ubx, lsl). After compensating for the loop time, I got:
* lsl: 1.006 s
* ubx: 0.876 s
* and: 0.918 s
even though ubx has a latency of two cycles.
I then took the AND version and shifted it to the start of the file.
This small change in alignment pushed it up to 1.048 s which is 14 %
slower.
-- Michael
