My guess is also that you've linked with a version of malloc that's not
thread-safe. Try linking your application with -lpthread; that should
link with the thread-safe libraries.
Steve
Ali Saidi wrote:
Hi Jiayuan,
I'm not completely sure, it really depends on what you're new thread
code is doing. From a simulation stand point all M5 is doing is
providing an implementation of the brk() syscall. If malloc() increases
the break size, physical frames are allocated and mapped the virtual
addresses between the old brk and the new one (syscall_emul.cc:110). I
can't see how this would be a problem, but no guarantees. My guess
would be something to do with malloc() not expecting a threaded process.
Ali
On Jun 12, 2007, at 11:26 PM, Jiayuan Meng wrote:
Hi Ali,
Thanks for the hint and I did find that there is an error. But I'm not
sure whether it's the problem with my implementation or with M5.
Here is the problem:
void thread_main()
{
int* x = new x[10];
delete [] x;
my_exit(); // inlined assembly(asm volatile (".byte 0x61,
0x00,0x00,0x40))
}
main()
{
for(int n=0; n<4; n++)
thread_create(&thread_main); // inlined assembly(asm volatile
(".byte 0x62, 0x00,0x00,0x40))
wait(); // inlined assembly(asm volatile (".byte 0x63,
0x00,0x00,0x40))
}
in the following example, I am trying to create 4 threads running
simultaneously. Each of the thread allocate some heap space and then
free it.
I am expecting that the "x"s in each thread is assigned to a different
address in the heap. But I found that the 4 threads allocate exactly
the same address to the 4 "x"s, thus, when they try to free "x", it is
freed four times and the application invokes an error:
*** glibc detected *** double free or corruption (fasttop):
0x00000001201d8a40 ***
and this error is always followed by the "stat64 unimplemented" message.
Can you also give me some hints about how to solve this? why does the
four threads assign their "x" the same address? how can I get around
with this?
Thanks!
Jiayuan
----- Original Message -----
*From:* Ali Saidi <mailto:[EMAIL PROTECTED]>
*To:* M5 users mailing list <mailto:[email protected]>
*Sent:* 2007年6月13日 10:24 AM
*Subject:* Re: [m5-users] thread alloc/dealloc error and stat64
system call
I'm not sure I know why stat64 is being called. It could be that
one of your new instructions isn't what you think it is and the
program execution path changes to some error handler, or something
else. You probably want to create an instruction trace and make
sure it's doing what you think it is. If that is the case then
implementing stat64 shouldn't be that difficult, just take a look
at fstat64. stat64 is the same thing but instead of argument 1
being a file descriptor it's a path to a file.
Ali
On Jun 12, 2007, at 8:14 PM, Jiayuan Meng wrote:
Hi all,
As I am trying to run a thread in SE mode, I made up the
following code:
void thread_main()
{
int* x = new x[10];
delete [] x;
my_exit(); // inlined assembly(asm volatile (".byte 0x61,
0x00,0x00,0x40))
}
main()
{
launch(&thread_main); // inlined assembly(asm volatile
(".byte 0x62, 0x00,0x00,0x40))
wait(); // inlined assembly(asm volatile (".byte 0x63,
0x00,0x00,0x40))
}
To launch this thread, what I did was: allocate a stack, assign
the pc, and activate the thread context on another cpu. my_exit()
will tell the simulator that this thread is finished and the
simulator will deallocate/halt its thread context.
The extened assemblies are implemented following the M5FUNC
pseudo instructions.
I use crosstool's g++ 3.4.3 to compile the code to alpha-linux.
M5 is compiled on a 64bit x86 machine.
I get the following message:
fatal: syscall stat64 (#425) unimplemented.
how ever, if I just change the thread_main to:
void thread_main()
{
int* x = new x
delete x;
my_exit();
}
The error will be gone. What can I do to allow the first case to
work? is there any patch for system call stat64?
Thanks!
Jiayuan
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