Re: [julia-users] Segmentation fault during Julia compilation

2015-08-31 Thread Patrick O'Leary 
Corresponding issue: https://github.com/JuliaLang/julia/issues/12840

On Monday, August 31, 2015 at 9:07:47 AM UTC-5, Mahesh Waidande wrote:
>
> Hi All,
>
>
> I am working on building/porting Julia on ppc64le architecture. I am using 
> Ubuntu 14.10 on top of ppc64le hardware, while compiling Julia code (master 
> branch) I was getting segmentation fault, I am able to resolve this 
> segmentation fault by turning on ‘MEMDEBUG’ flag from ‘src/options.h’ 
> file.  
>
>
> I decided to work more this issue and try to find out root cause of 
> segmentation fault, so I started studying/understanding memory management 
> of Julia. I have couple of questions in my mind regarding memory management 
> of Julia and I want to discuss those here. 
>
> 1. While defining ‘REGION_PG_COUNT’ macro, 4096 value is used, I want to 
> know what is the significance of 4096?
>   If 4096 is indicates page-size then this code is valid 
> or work fine on amd64/x86_64   architecture where page size 4k and it may 
> behave abnormally in case of PPC64 where page size is 64k, basically here I 
> want to discuss the impact of large page size on Julia code and what all 
> other things I need to take into consideration while porting Julia on 
> PPC64le.  
>
> 2. Past few days I was working on understanding memory management scheme 
> of Julia and I find it bit of difficult and time consuming process though I 
> have some success. I want to know is there any official / unofficial 
> document around which will help me understand it.
>
> Any suggestions/pointers on above mention points are much appreciated.
>
> -Mahesh  
>
> On Tue, Aug 18, 2015 at 8:11 PM, Jameson Nash  > wrote:
>
>> It is a considerable performance impact to run with MEMDEBUG, but 
>> otherwise has no side-effects. It is not necessary to run with this flag in 
>> production (and probably not helpful either, since you wouldn't have a 
>> debugger attached).
>>
>>
>> On Tue, Aug 18, 2015 at 9:53 AM Mahesh Waidande > > wrote:
>>
>>> Hi Jamseson,
>>>
>>> Thanks for explaining memory allocations on PPC and providing pointers 
>>> on resolving segmentation fault, pointers are really helpful and I am 
>>> working on those. I am able to compile Julia master branch after turning 
>>> ‘MEMDEBUG‘ flag on from options.h file, compilation went smooth and I am 
>>> able to see the Julia prompt. Although I will continue to work on finding 
>>> root cause of segmentation fault, occur at a time of Julia initialization. 
>>>
>>>
>>> I think when we turn on the ‘MEMDEBUG‘ flag it will reduce a performance 
>>> of Julia bit as with MEMDEBUG no memory pools are used and all allocation 
>>> is treated as big. 
>>>
>>>
>>> Apart from performance issue, I have few questions in my mind and I 
>>> would like to discuss those,
>>> 1. Apart from performance hit, is there any other functionality has 
>>> impacted due to turning on ‘MEMDEBUG’ flag OR what are side effects of 
>>> turning ‘MEMDEBUG’ flag on?
>>> 2. Should I use these settings (turning MEMDEBUG flag on) in production 
>>> environment or in release mode?
>>>
>>>
>>>
>>> -Mahesh 
>>>
>>> On Fri, Aug 14, 2015 at 10:03 PM, Jameson Nash >> > wrote:
>>>
 It's a JIT copy of a julia function named "new". The last time this 
 error popped up, it was due to an error in the free_page function logic to 
 compute whether it was safe to free the current page (since PPC using 
 large 
 pages). One place to check then is to ensure the invalid pointer hadn't 
 accidentally being deleted by an madvise(DONTNEED) for an unrelated page 
 free operations.

 Beyond that, I would suggest trying with the `MEMDEBUG` turned on in 
 options.h (which will also disable the `free_page` function).

 Also, when you have gdb running, there are many more useful things to 
 print than just the backtrace. For starters, I would suggest looking at 
 `disassembly` and `info registers`. Also, go `up` on the stack trace and 
 look at `jl_(f->linfo)`, `jl_(jl_uncompress_ast(f->linfo, 
 f->linfo->ast))`, 
 and `jl_(args[0])` / `jl_(args[1])`


 On Fri, Aug 14, 2015 at 9:07 AM Mahesh Waidande  wrote:

> Hi All, 
>
> I am working on building/porting Julia on ppc64le architecture. I am 
> using Ubuntu 14.10 on top of ppc64le hardware, while compiling Julia 
> code(master branch) I am getting segmentation fault. I tried to debug 
> segmentation fault with tools like gdb/vgdb , valgrind , electric-fence 
> etc. but I not able to find a root cause of it. I need some 
> help/pointers/suggestions on how I resolve it. 
>
> Here are some details which will help you to diagnose a problem,
>
> 1. Machine details : 
> $ uname -a
> Linux pts00433-vm1 3.16.0-30-generic #40-Ubuntu SMP Mon Jan 12 
> 22:07:11 UTC 2015 ppc64le ppc64le ppc64le

Re: [julia-users] Segmentation fault during Julia compilation

2015-08-31 Thread Mahesh Waidande 
Hi All,


I am working on building/porting Julia on ppc64le architecture. I am using
Ubuntu 14.10 on top of ppc64le hardware, while compiling Julia code (master
branch) I was getting segmentation fault, I am able to resolve this
segmentation fault by turning on ‘MEMDEBUG’ flag from ‘src/options.h’
file.


I decided to work more this issue and try to find out root cause of
segmentation fault, so I started studying/understanding memory management
of Julia. I have couple of questions in my mind regarding memory management
of Julia and I want to discuss those here.

1. While defining ‘REGION_PG_COUNT’ macro, 4096 value is used, I want to
know what is the significance of 4096?
  If 4096 is indicates page-size then this code is valid or
work fine on amd64/x86_64   architecture where page size 4k and it may
behave abnormally in case of PPC64 where page size is 64k, basically here I
want to discuss the impact of large page size on Julia code and what all
other things I need to take into consideration while porting Julia on
PPC64le.

2. Past few days I was working on understanding memory management scheme of
Julia and I find it bit of difficult and time consuming process though I
have some success. I want to know is there any official / unofficial
document around which will help me understand it.

Any suggestions/pointers on above mention points are much appreciated.

-Mahesh

On Tue, Aug 18, 2015 at 8:11 PM, Jameson Nash  wrote:

> It is a considerable performance impact to run with MEMDEBUG, but
> otherwise has no side-effects. It is not necessary to run with this flag in
> production (and probably not helpful either, since you wouldn't have a
> debugger attached).
>
>
> On Tue, Aug 18, 2015 at 9:53 AM Mahesh Waidande <
> mahesh.waidande1...@gmail.com> wrote:
>
>> Hi Jamseson,
>>
>> Thanks for explaining memory allocations on PPC and providing pointers on
>> resolving segmentation fault, pointers are really helpful and I am working
>> on those. I am able to compile Julia master branch after turning ‘MEMDEBUG‘
>> flag on from options.h file, compilation went smooth and I am able to see
>> the Julia prompt. Although I will continue to work on finding root cause of
>> segmentation fault, occur at a time of Julia initialization.
>>
>>
>> I think when we turn on the ‘MEMDEBUG‘ flag it will reduce a performance
>> of Julia bit as with MEMDEBUG no memory pools are used and all allocation
>> is treated as big.
>>
>>
>> Apart from performance issue, I have few questions in my mind and I would
>> like to discuss those,
>> 1. Apart from performance hit, is there any other functionality has
>> impacted due to turning on ‘MEMDEBUG’ flag OR what are side effects of
>> turning ‘MEMDEBUG’ flag on?
>> 2. Should I use these settings (turning MEMDEBUG flag on) in production
>> environment or in release mode?
>>
>>
>>
>> -Mahesh
>>
>> On Fri, Aug 14, 2015 at 10:03 PM, Jameson Nash  wrote:
>>
>>> It's a JIT copy of a julia function named "new". The last time this
>>> error popped up, it was due to an error in the free_page function logic to
>>> compute whether it was safe to free the current page (since PPC using large
>>> pages). One place to check then is to ensure the invalid pointer hadn't
>>> accidentally being deleted by an madvise(DONTNEED) for an unrelated page
>>> free operations.
>>>
>>> Beyond that, I would suggest trying with the `MEMDEBUG` turned on in
>>> options.h (which will also disable the `free_page` function).
>>>
>>> Also, when you have gdb running, there are many more useful things to
>>> print than just the backtrace. For starters, I would suggest looking at
>>> `disassembly` and `info registers`. Also, go `up` on the stack trace and
>>> look at `jl_(f->linfo)`, `jl_(jl_uncompress_ast(f->linfo, f->linfo->ast))`,
>>> and `jl_(args[0])` / `jl_(args[1])`
>>>
>>>
>>> On Fri, Aug 14, 2015 at 9:07 AM Mahesh Waidande <
>>> mahesh.waidande1...@gmail.com> wrote:
>>>
 Hi All,

 I am working on building/porting Julia on ppc64le architecture. I am
 using Ubuntu 14.10 on top of ppc64le hardware, while compiling Julia
 code(master branch) I am getting segmentation fault. I tried to debug
 segmentation fault with tools like gdb/vgdb , valgrind , electric-fence
 etc. but I not able to find a root cause of it. I need some
 help/pointers/suggestions on how I resolve it.

 Here are some details which will help you to diagnose a problem,

 1. Machine details :
 $ uname -a
 Linux pts00433-vm1 3.16.0-30-generic #40-Ubuntu SMP Mon Jan 12 22:07:11
 UTC 2015 ppc64le ppc64le ppc64le GNU/Linux
 $

 2. Snapshot of ‘make debug’ log
 make[1]: Leaving directory '/home/test/Mahesh/julia/julia/base'
 make[1]: Entering directory '/home/test/Mahesh/julia/julia'
  cd base && /home/test/Mahesh/julia/julia/usr/bin/julia-debug -C native
 --output-ji /home/test/Mahesh/julia/julia/usr/lib/julia/inference0.ji -f

Re: [julia-users] Segmentation fault during Julia compilation

2015-08-18 Thread Mahesh Waidande 
Hi Jamseson,

Thanks for explaining memory allocations on PPC and providing pointers on
resolving segmentation fault, pointers are really helpful and I am working
on those. I am able to compile Julia master branch after turning ‘MEMDEBUG‘
flag on from options.h file, compilation went smooth and I am able to see
the Julia prompt. Although I will continue to work on finding root cause of
segmentation fault, occur at a time of Julia initialization.


I think when we turn on the ‘MEMDEBUG‘ flag it will reduce a performance of
Julia bit as with MEMDEBUG no memory pools are used and all allocation is
treated as big.


Apart from performance issue, I have few questions in my mind and I would
like to discuss those,
1. Apart from performance hit, is there any other functionality has
impacted due to turning on ‘MEMDEBUG’ flag OR what are side effects of
turning ‘MEMDEBUG’ flag on?
2. Should I use these settings (turning MEMDEBUG flag on) in production
environment or in release mode?


-Mahesh

On Fri, Aug 14, 2015 at 10:03 PM, Jameson Nash vtjn...@gmail.com wrote:

 It's a JIT copy of a julia function named new. The last time this error
 popped up, it was due to an error in the free_page function logic to
 compute whether it was safe to free the current page (since PPC using large
 pages). One place to check then is to ensure the invalid pointer hadn't
 accidentally being deleted by an madvise(DONTNEED) for an unrelated page
 free operations.

 Beyond that, I would suggest trying with the `MEMDEBUG` turned on in
 options.h (which will also disable the `free_page` function).

 Also, when you have gdb running, there are many more useful things to
 print than just the backtrace. For starters, I would suggest looking at
 `disassembly` and `info registers`. Also, go `up` on the stack trace and
 look at `jl_(f-linfo)`, `jl_(jl_uncompress_ast(f-linfo, f-linfo-ast))`,
 and `jl_(args[0])` / `jl_(args[1])`


 On Fri, Aug 14, 2015 at 9:07 AM Mahesh Waidande 
 mahesh.waidande1...@gmail.com wrote:

 Hi All,

 I am working on building/porting Julia on ppc64le architecture. I am
 using Ubuntu 14.10 on top of ppc64le hardware, while compiling Julia
 code(master branch) I am getting segmentation fault. I tried to debug
 segmentation fault with tools like gdb/vgdb , valgrind , electric-fence
 etc. but I not able to find a root cause of it. I need some
 help/pointers/suggestions on how I resolve it.

 Here are some details which will help you to diagnose a problem,

 1. Machine details :
 $ uname -a
 Linux pts00433-vm1 3.16.0-30-generic #40-Ubuntu SMP Mon Jan 12 22:07:11
 UTC 2015 ppc64le ppc64le ppc64le GNU/Linux
 $

 2. Snapshot of ‘make debug’ log
 make[1]: Leaving directory '/home/test/Mahesh/julia/julia/base'
 make[1]: Entering directory '/home/test/Mahesh/julia/julia'
  cd base  /home/test/Mahesh/julia/julia/usr/bin/julia-debug -C native
 --output-ji /home/test/Mahesh/julia/julia/usr/lib/julia/inference0.ji -f
 coreimg.jl

   Electric Fence 2.2 Copyright (C) 1987-1999 Bruce Perens 
 br...@perens.com
 Segmentation fault
 Makefile:175: recipe for target
 '/home/test/Mahesh/julia/julia/usr/lib/julia/inference0.ji' failed
 make[1]: *** [/home/test/Mahesh/julia/julia/usr/lib/julia/inference0.ji]
 Error 139
 make[1]: Leaving directory '/home/test/Mahesh/julia/julia'
 Makefile:64: recipe for target 'julia-inference' failed
 make: *** [julia-inference] Error 2

 3. gdb stack trace
 test@pts00433-vm1:~/Mahesh/julia/julia/base$ gdb --args
 /home/test/Mahesh/julia/julia/usr/bin/julia-debug -C native --output-ji
 /home/test/Mahesh/julia/julia/usr/lib/julia/inference0.ji -f coreimg.jl
 GNU gdb (Ubuntu 7.8-1ubuntu4) 7.8.0.20141001-cvs
 Copyright (C) 2014 Free Software Foundation, Inc.
 License GPLv3+: GNU GPL version 3 or later 
 http://gnu.org/licenses/gpl.html
 This is free software: you are free to change and redistribute it.
 There is NO WARRANTY, to the extent permitted by law.  Type show copying
 and show warranty for details.
 This GDB was configured as powerpc64le-linux-gnu.
 Type show configuration for configuration details.
 For bug reporting instructions, please see:
 http://www.gnu.org/software/gdb/bugs/.
 Find the GDB manual and other documentation resources online at:
 http://www.gnu.org/software/gdb/documentation/.
 For help, type help.
 Type apropos word to search for commands related to word...
 Reading symbols from
 /home/test/Mahesh/julia/julia/usr/bin/julia-debug...done.
 (gdb) b repl.c:532
 Breakpoint 1 at 0x10003a34: file repl.c, line 532.
 (gdb) r
 Starting program: /home/test/Mahesh/julia/julia/usr/bin/julia-debug -C
 native --output-ji
 /home/test/Mahesh/julia/julia/usr/lib/julia/inference0.ji -f coreimg.jl
 [Thread debugging using libthread_db enabled]
 Using host libthread_db library
 /lib/powerpc64le-linux-gnu/libthread_db.so.1.

   Electric Fence 2.2 Copyright (C) 1987-1999 Bruce Perens 
 br...@perens.com

 Breakpoint 1, main (argc=7, argv=0x3478) at repl.c:533
 533 {
 (gdb) c
 Continuing.

 Program

Re: [julia-users] Segmentation fault during Julia compilation

2015-08-14 Thread Jameson Nash 
It's a JIT copy of a julia function named new. The last time this error
popped up, it was due to an error in the free_page function logic to
compute whether it was safe to free the current page (since PPC using large
pages). One place to check then is to ensure the invalid pointer hadn't
accidentally being deleted by an madvise(DONTNEED) for an unrelated page
free operations.

Beyond that, I would suggest trying with the `MEMDEBUG` turned on in
options.h (which will also disable the `free_page` function).

Also, when you have gdb running, there are many more useful things to print
than just the backtrace. For starters, I would suggest looking at
`disassembly` and `info registers`. Also, go `up` on the stack trace and
look at `jl_(f-linfo)`, `jl_(jl_uncompress_ast(f-linfo, f-linfo-ast))`,
and `jl_(args[0])` / `jl_(args[1])`

On Fri, Aug 14, 2015 at 9:07 AM Mahesh Waidande 
mahesh.waidande1...@gmail.com wrote:

 Hi All,

 I am working on building/porting Julia on ppc64le architecture. I am using
 Ubuntu 14.10 on top of ppc64le hardware, while compiling Julia code(master
 branch) I am getting segmentation fault. I tried to debug segmentation
 fault with tools like gdb/vgdb , valgrind , electric-fence etc. but I not
 able to find a root cause of it. I need some help/pointers/suggestions on
 how I resolve it.

 Here are some details which will help you to diagnose a problem,

 1. Machine details :
 $ uname -a
 Linux pts00433-vm1 3.16.0-30-generic #40-Ubuntu SMP Mon Jan 12 22:07:11
 UTC 2015 ppc64le ppc64le ppc64le GNU/Linux
 $

 2. Snapshot of ‘make debug’ log
 make[1]: Leaving directory '/home/test/Mahesh/julia/julia/base'
 make[1]: Entering directory '/home/test/Mahesh/julia/julia'
  cd base  /home/test/Mahesh/julia/julia/usr/bin/julia-debug -C native
 --output-ji /home/test/Mahesh/julia/julia/usr/lib/julia/inference0.ji -f
 coreimg.jl

   Electric Fence 2.2 Copyright (C) 1987-1999 Bruce Perens 
 br...@perens.com
 Segmentation fault
 Makefile:175: recipe for target
 '/home/test/Mahesh/julia/julia/usr/lib/julia/inference0.ji' failed
 make[1]: *** [/home/test/Mahesh/julia/julia/usr/lib/julia/inference0.ji]
 Error 139
 make[1]: Leaving directory '/home/test/Mahesh/julia/julia'
 Makefile:64: recipe for target 'julia-inference' failed
 make: *** [julia-inference] Error 2

 3. gdb stack trace
 test@pts00433-vm1:~/Mahesh/julia/julia/base$ gdb --args
 /home/test/Mahesh/julia/julia/usr/bin/julia-debug -C native --output-ji
 /home/test/Mahesh/julia/julia/usr/lib/julia/inference0.ji -f coreimg.jl
 GNU gdb (Ubuntu 7.8-1ubuntu4) 7.8.0.20141001-cvs
 Copyright (C) 2014 Free Software Foundation, Inc.
 License GPLv3+: GNU GPL version 3 or later 
 http://gnu.org/licenses/gpl.html
 This is free software: you are free to change and redistribute it.
 There is NO WARRANTY, to the extent permitted by law.  Type show copying
 and show warranty for details.
 This GDB was configured as powerpc64le-linux-gnu.
 Type show configuration for configuration details.
 For bug reporting instructions, please see:
 http://www.gnu.org/software/gdb/bugs/.
 Find the GDB manual and other documentation resources online at:
 http://www.gnu.org/software/gdb/documentation/.
 For help, type help.
 Type apropos word to search for commands related to word...
 Reading symbols from
 /home/test/Mahesh/julia/julia/usr/bin/julia-debug...done.
 (gdb) b repl.c:532
 Breakpoint 1 at 0x10003a34: file repl.c, line 532.
 (gdb) r
 Starting program: /home/test/Mahesh/julia/julia/usr/bin/julia-debug -C
 native --output-ji
 /home/test/Mahesh/julia/julia/usr/lib/julia/inference0.ji -f coreimg.jl
 [Thread debugging using libthread_db enabled]
 Using host libthread_db library
 /lib/powerpc64le-linux-gnu/libthread_db.so.1.

   Electric Fence 2.2 Copyright (C) 1987-1999 Bruce Perens 
 br...@perens.com

 Breakpoint 1, main (argc=7, argv=0x3478) at repl.c:533
 533 {
 (gdb) c
 Continuing.

 Program received signal SIGSEGV, Segmentation fault.
 0x3fffb6970078 in julia.new_0 ()
 (gdb) where
 #0  0x3fffb6970078 in julia.new_0 ()
 #1  0x3fffb6b3b820 in jl_apply (f=0x3ffd9ac1de10, args=0x3fffde28,
 nargs=2) at julia.h:1263
 #2  0x3fffb6b4137c in jl_trampoline (F=0x3ffd9ac1de10,
 args=0x3fffde28, nargs=2) at builtins.c:979
 #3  0x3fffb6b2b084 in jl_apply (f=0x3ffd9ac1de10, args=0x3fffde28,
 nargs=2) at julia.h:1263
 #4  0x3fffb6b328d0 in jl_apply_generic (F=0x3ffd9ac1dd90,
 args=0x3fffde28, nargs=2) at gf.c:1675
 #5  0x3fffb6c2d9a0 in jl_apply (f=0x3ffd9ac1dd90, args=0x3fffde28,
 nargs=2) at julia.h:1263
 #6  0x3fffb6c2e014 in do_call (f=0x3ffd9ac1dd90, args=0x3ffd9ac215a8,
 nargs=2, eval0=0x0, locals=0x0, nl=0, ngensym=0)
 at interpreter.c:65
 #7  0x3fffb6c2eec4 in eval (e=0x3ffd9ac1ddd0, locals=0x0, nl=0,
 ngensym=0) at interpreter.c:212
 #8  0x3fffb6c2dc20 in jl_interpret_toplevel_expr (e=0x3ffd9ac1ddd0) at
 interpreter.c:27
 #9  0x3fffb6c55eac in jl_toplevel_eval_flex (e=0x3ffd9ac1ddb0, fast=1)
 at