shared memory problem on ARM v5TE using threads
Heiko Schocher
hs at denx.de
Fri Dec 4 06:23:45 EST 2009
Hello,
I have the following shared mem problem on a ARM v5TE
processor using Linux version 2.6.28,
-bash-3.2# cat /proc/cpuinfo
Processor : Feroceon 88FR131 rev 1 (v5l)
BogoMIPS : 799.53
Features : swp half thumb fastmult edsp
CPU implementer : 0x56
CPU architecture: 5TE
CPU variant : 0x2
CPU part : 0x131
CPU revision : 1
The testscript [1] starts 2 processes. One write
process with one thread, which writes in a shared memory.
The second process starts 4 threads, which all read from
this shared memory. This don;t work on this processor [4].
The same demoprogramm works fine on ppc, i386 or on a
ARMv6 based board [3][6] ...
If I start 4 read processes, which themselves starts only
one readthread [5], the demoprogramm works fine!
Also, if I start one read process, which only attaches
the shared memory once with shmat(), and then starts 4
read threads, and all this 4 read threads using
the same shared memory addr, returned from shmat(),
this works as expected.
Any ideas, hints ... ?
TIA
bye,
Heiko
--
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
[1] Testscript
#!/bin/sh
echo "Compile"
gcc -o shmtest2 shmtest2.c -lpthread
echo "Run shmtest2"
./shmtest2 write 1 &
./shmtest2 read 4 &
[2] demoprogramm, shmtest2.c
#include <pthread.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
extern void exit();
struct Entry
{
char ident_name[1000];
unsigned int tipc_nr;
unsigned int pid;
unsigned int in_msg;
unsigned int out_msg;
unsigned int rxQueueLength;
};
void* attachSharedMem(int shmid)
{
void* addr = shmat(shmid, NULL, 0);
if ((addr != 0) && (0xffffffff != (unsigned int)addr))
{
printf("attach shared mem:%x\n",addr);
}
else
{
printf("shmat failed");
addr = 0;
}
return addr;
}
int createSharedMem()
{
key_t key = 1000; /* key to be passed to shmget() */
int shmflg; /* shmflg to be passed to shmget() */
int shmid; /* return value from shmget() */
int size; /* size to be passed to shmget() */
size = 60000;
shmflg = IPC_CREAT | 0666;
if ((shmid = shmget (key, size, shmflg)) == -1)
{
printf("shmget failed");
shmid = 0;
}
printf("Shared memory Id:%d\n",shmid);
return shmid;
}
void* setupSharedMem()
{
int shmid = createSharedMem();
void* addrShm = attachSharedMem(shmid);
return addrShm;
}
void *readThread(void *t)
{
struct Entry* entry = 0;
int shmid = (int)t;
void* addrShm = attachSharedMem(shmid);
if (addrShm != 0)
{
printf("Start Read Thread addr:%x\n",addrShm);
entry = (struct Entry*)addrShm;
entry->in_msg = 0;
entry->out_msg = 0;
int i=0;
while(i < 60)
{
entry->in_msg += 1000;
sleep(1);
printf("Read from entry in_msg=%d, out_msg=%d, addr=%x\n",entry->in_msg,entry->out_msg, addrShm);
i++;
}
}
pthread_exit(NULL);
}
void *writeThread(void *t)
{
struct Entry* entry = 0;
unsigned int threadId = (unsigned int)t;
void* addrShm = setupSharedMem();
if (addrShm != 0)
{
printf("Start Write Thread %d, addr:%x\n",threadId,addrShm);
entry = (struct Entry*)addrShm;
strcpy(entry->ident_name,"this is a test entry");
entry->in_msg = 0;
entry->out_msg = 0;
entry->rxQueueLength = 20000;
entry->pid = threadId;
entry->tipc_nr = 1000;
int i=0;
while(i < 60)
{
entry->out_msg += 1000;
sleep(1);
i++;
}
}
pthread_exit(NULL);
}
main(int argc, char* argv[])
{
//check the arguments
if (argc != 3)
{
printf("Arguments are [read|write] [number of threads]\n");
exit(1);
}
unsigned int mode = 0;
unsigned int nbrOfThreads = 0;
if (strcmp(argv[1],"write") == 0)
{
printf("Write to in_msg\n");
mode = 1;
}
if (strcmp(argv[1],"read") == 0)
{
printf("Read from in_msg\n");
mode = 2;
}
nbrOfThreads = atoi(argv[2]);
pthread_t threads[nbrOfThreads];
pthread_attr_t attr;
/* Initialize and set thread detached attribute */
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
unsigned int t;
int rc;
for(t=0; t<nbrOfThreads; t++)
{
printf("Creating thread %ld\n", t);
if (mode == 1)
{
rc = pthread_create(&threads[t], &attr, writeThread, (void *)t);
}
else
{
int shmid = createSharedMem(t);
rc = pthread_create(&threads[t], &attr, readThread, (void *)shmid);
}
if (rc)
{
printf("ERROR; return code from pthread_create() is %d\n", rc);
exit(-1);
}
}
void* status;
pthread_attr_destroy(&attr);
for(t=0; t<nbrOfThreads; t++)
{
pthread_join(threads[t], &status);
}
printf("All %s threads finished, exit\n",mode == 1 ? "write":"read");
exit(0);
}
[3] ARMv6 processor cpuinfo
-bash-3.2# cat /proc/version
Linux version 2.6.32-rc6 (dzu at pollux.denx.de) (gcc version 4.2.2) #4 Thu Dec 3 12:31:13 CET 2009
-bash-3.2# cat /proc/cpuinfo
Processor : ARMv6-compatible processor rev 4 (v6l)
BogoMIPS : 398.13
Features : swp half thumb fastmult vfp edsp java
CPU implementer : 0x41
CPU architecture: 6TEJ
CPU variant : 0x0
CPU part : 0xb36
CPU revision : 4
[4] Log from Demoprogramm, not working
-bash-3.2# ./shtest2.sh
Run shmtest2
Read from in_msg
Creating thread 0
Shared memory Id:0
attach shared mem:40961000
Start Read Thread addr:40961000
Write to in_msg
Creating thread 0
Shared memory Id:0
attach shared mem:40961000
Start Write Thread 0, addr:40961000
348: write new mesg: 0
Read from in_msg
Creating thread 0
Shared memory Id:0
attach shared mem:40961000
Start Read Thread addr:40961000
Creating thread 1
Shared memory Id:0
Read from in_msg
Creating thread 0
Shared memory Id:0
attach shared mem:40961000
Start Read Thread addr:40961000
attach shared mem:41170000
Start Read Thread addr:41170000
Read from in_msg
Creating thread 0
Shared memory Id:0
attach shared mem:40961000
Start Read Thread addr:40961000
-bash-3.2# Read from entry in_msg=1000, out_msg=0, addr=40961000
Read from entry in_msg=0, out_msg=0, addr=40961000
Read from entry in_msg=2000, out_msg=1000, addr=40961000
Read from entry in_msg=1000, out_msg=0, addr=41170000
Read from entry in_msg=3000, out_msg=1000, addr=40961000
Read from entry in_msg=4000, out_msg=1000, addr=40961000
Read from entry in_msg=2000, out_msg=0, addr=40961000
Read from entry in_msg=5000, out_msg=2000, addr=40961000
Read from entry in_msg=3000, out_msg=0, addr=41170000
Read from entry in_msg=6000, out_msg=2000, addr=40961000
Read from entry in_msg=7000, out_msg=2000, addr=40961000
Read from entry in_msg=4000, out_msg=0, addr=40961000
Read from entry in_msg=8000, out_msg=3000, addr=40961000
Read from entry in_msg=5000, out_msg=0, addr=41170000
Read from entry in_msg=9000, out_msg=3000, addr=40961000
Read from entry in_msg=10000, out_msg=3000, addr=40961000
[...]
[5] Testscript which starts 4 read processes each with
one read thread
#!/bin/sh
echo "Compile"
gcc -o shmtest2 shmtest2.c -lpthread
echo "Run shmtest2"
./shmtest2 write 1 &
./shmtest2 read 1 &
./shmtest2 read 1 &
./shmtest2 read 1 &
./shmtest2 read 1 &
[6] working log on ARMv6
-bash-3.2# ./shtest2.sh
Run shmtest2
Write to in_msg
Creating thread 0
Shared memory Id:0
attach shared mem:40960000
Start Write Thread 0, addr:40960000
Read from in_msg
Creating thread 0
Shared memory Id:0
attach shared mem:40960000
Start Read Thread addr:40960000
Creating thread 1
Shared memory Id:0
Creating thread 2
Shared memory Id:0
Creating thread 3
Shared memory Id:0
attach shared mem:4216f000
Start Read Thread addr:4216f000
attach shared mem:4217e000
Start Read Thread addr:4217e000
attach shared mem:4218d000
Start Read Thread addr:4218d000
-bash-3.2# Read from entry in_msg=1000, out_msg=1000, addr=40960000
Read from entry in_msg=2000, out_msg=1000, addr=4216f000
Read from entry in_msg=3000, out_msg=1000, addr=4217e000
Read from entry in_msg=4000, out_msg=1000, addr=4218d000
Read from entry in_msg=5000, out_msg=2000, addr=40960000
Read from entry in_msg=6000, out_msg=2000, addr=4216f000
Read from entry in_msg=7000, out_msg=2000, addr=4217e000
Read from entry in_msg=8000, out_msg=2000, addr=4218d000
Read from entry in_msg=9000, out_msg=3000, addr=40960000
Read from entry in_msg=10000, out_msg=3000, addr=4216f000
Read from entry in_msg=11000, out_msg=3000, addr=4217e000
Read from entry in_msg=12000, out_msg=3000, addr=4218d000
Read from entry in_msg=13000, out_msg=4000, addr=40960000
Read from entry in_msg=14000, out_msg=4000, addr=4216f000
Read from entry in_msg=15000, out_msg=4000, addr=4217e000
Read from entry in_msg=16000, out_msg=4000, addr=4218d000
[...]
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