[Bug 95438] Elemental demo compute shader takes ages to compile

[Bug 95438] Elemental demo compute shader takes ages to compile

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 2419 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=95438

            Bug ID: 95438
           Summary: Elemental demo compute shader takes ages to compile
           Product: Mesa
           Version: git
          Hardware: Other
                OS: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Drivers/Gallium/radeonsi
          Assignee: dri-devel@lists.freedesktop.org
          Reporter: airlied@freedesktop.org
        QA Contact: dri-devel@lists.freedesktop.org

Created attachment 123804
  --> https://bugs.freedesktop.org/attachment.cgi?id=123804&action=edit
compute shader and GLSL/TGSI/llvm IR.

After fixing the two GLSL bugs, I hit a case where one of the compute shaders
in 
ElementalDemo takes a long long time to compile and consumes a lot of memory
doing so.


#0  llvm::SUnit::addPred (this=this@entry=0x7fa8da02fae0, D=...,
Required=Required@entry=true)
    at /home/airlied/devel/llvm/lib/CodeGen/ScheduleDAG.cpp:67
#1  0x00007fa92c946d2d in llvm::ScheduleDAGInstrs::addPhysRegDataDeps
(this=this@entry=0x7fa9248d3840, SU=SU@entry=0x7fa8d9833c40, 
    OperIdx=OperIdx@entry=8) at
/home/airlied/devel/llvm/lib/CodeGen/ScheduleDAGInstrs.cpp:318
#2  0x00007fa92c947198 in llvm::ScheduleDAGInstrs::addPhysRegDeps
(this=this@entry=0x7fa9248d3840, SU=SU@entry=0x7fa8d9833c40, 
    OperIdx=OperIdx@entry=8) at
/home/airlied/devel/llvm/lib/CodeGen/ScheduleDAGInstrs.cpp:370
#3  0x00007fa92c94fd1e in llvm::ScheduleDAGInstrs::buildSchedGraph
(this=this@entry=0x7fa9248d3840, AA=0x7fa8e2e55b10, 
    RPTracker=RPTracker@entry=0x0, PDiffs=PDiffs@entry=0x0, LIS=LIS@entry=0x0,
TrackLaneMasks=TrackLaneMasks@entry=false)
    at /home/airlied/devel/llvm/lib/CodeGen/ScheduleDAGInstrs.cpp:959
#4  0x00007fa92c8ff02b in (anonymous namespace)::SchedulePostRATDList::schedule
(this=this@entry=0x7fa9248d3840)
    at /home/airlied/devel/llvm/lib/CodeGen/PostRASchedulerList.cpp:391
#5  0x00007fa92c8ffbbe in (anonymous
namespace)::PostRAScheduler::runOnMachineFunction (this=0x7fa8e284a500, Fn=...)
    at /home/airlied/devel/llvm/lib/CodeGen/PostRASchedulerList.cpp:360
#6  0x00007fa92c880721 in llvm::MachineFunctionPass::runOnFunction
(this=0x7fa8e284a500, F=...)
    at /home/airlied/devel/llvm/lib/CodeGen/MachineFunctionPass.cpp:60

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 4017 bytes --]

[-- Attachment #2: Type: text/plain, Size: 160 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 95438] Elemental demo compute shader takes ages to compile

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 1375 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=95438

--- Comment #1 from Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl> ---
Last I looked at the elemental demo, we have multiple issues:

- The shared array (1024 elements) get wrongly promoted to a private array.
There is a fix for that at
https://lists.freedesktop.org/archives/mesa-dev/2016-April/113832.html

- in radeonsi we compile arrays to vectors with insert/extract element. This
pretty much results in the array being SSA version, which results in a very
large program.

- a 1024 element vector does not fit in 256 VGPR's so LLVM tries to load and
spill around every operation and therefore every versioned array element takes
scratch space.

- As a result I needed 7 MiB of scratch space per wave, or 6,7 GiB in total. 
This overflows the 32-bit buffer size and we only allocate a smaller buffer.

-  This resulted in hangs (or maybe long long shader execution times, not
really sure...).

So not sure how long a long long time is, last I tried (which admittedly is
some weeks ago) I certainly could get past the compilation stage. If you did
get past that and did not get hangs, I'm not sure why.

Fixing the first problem also circumvents problems 2 & 3, although it would be
nice to get those fixed as well.

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 2258 bytes --]

[-- Attachment #2: Type: text/plain, Size: 160 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 95438] Elemental demo compute shader takes ages to compile

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 317 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=95438

--- Comment #2 from Dave Airlie <airlied@freedesktop.org> ---
https://patchwork.freedesktop.org/patch/82260/

Looks like Bas's patch herre actually fixes this. sorry for the noise.

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 1166 bytes --]

[-- Attachment #2: Type: text/plain, Size: 160 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 95438] Elemental demo compute shader takes ages to compile

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 298 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=95438

--- Comment #3 from Dave Airlie <airlied@freedesktop.org> ---
with your patch any my two on llvm master and mesa master I'm running
elementaldemo in 4.3 mode now.

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 1086 bytes --]

[-- Attachment #2: Type: text/plain, Size: 160 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 95438] Elemental demo compute shader takes ages to compile

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 368 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=95438

--- Comment #4 from Marek Olšák <maraeo@gmail.com> ---
(In reply to Dave Airlie from comment #3)
> with your patch any my two on llvm master and mesa master I'm running
> elementaldemo in 4.3 mode now.

So can we close the bug?

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 1224 bytes --]

[-- Attachment #2: Type: text/plain, Size: 160 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 95438] Elemental demo compute shader takes ages to compile

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 534 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=95438

Marek Olšák <maraeo@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #5 from Marek Olšák <maraeo@gmail.com> ---
Closing as the scratch buffer issue was fixed.

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 2032 bytes --]

[-- Attachment #2: Type: text/plain, Size: 160 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel