Re: [PATCH 1/1] mips: fault.c: Port OOM changes to do_page_fault

From: Kautuk Consul
Date: Fri Dec 23 2011 - 06:42:39 EST


>
> Without these changes, my MIPS board encounters many hang and livelock
> scenarios.
> After applying this patch, OOM feature performance improves according to
> my testing.
>

Just to clarify the hang scenario I am talking about, the test case I
used to reproduce
this problem is attached to this email.
Running this a few times hangs my console and then even Ctrl-C signals
do not get handled
and I also do not get back the command prompt.

After applying this patch things seem to improve, but there are still
some hangs which I
encounter which I am further trying to debug.

However, since the generic part of the kernel(mm/filemap.c) now
supports killable and
retryable page fault handling, I thought that this change would be
valid for MIPS too.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <unistd.h>

#define ALLOC_BYTE 512*1024
#define COUNT 50

void *alloc_function_one( void *ptr );
void *alloc_function_two( void *ptr );
void *alloc_function_three( void *ptr );
void *alloc_function_four( void *ptr );
void *alloc_function_five( void *ptr );
void *enable_function( void *ptr );


int main(int argc, char *argv[])
{
pthread_t thread1, thread2, thread3, thread4, thread5;
char *message1 = "Thread 1";
char *message2 = "Thread 2";
char *message3 = "Thread 3";
char *message4 = "Thread 4";
char *message5 = "Thread 5";
int iret1 = -1;
int iret2 = -1;
int iret3 = -1;
int iret4 = -1;
int iret5 = -1;
fork();
iret1 = pthread_create( &thread1, NULL, alloc_function_one, (void*) message1);
iret2 = pthread_create( &thread2, NULL, alloc_function_two, (void*) message2);
iret2 = pthread_create( &thread3, NULL, alloc_function_three, (void*) message2);
iret2 = pthread_create( &thread4, NULL, alloc_function_four, (void*) message2);
iret2 = pthread_create( &thread5, NULL, alloc_function_five, (void*) message2);

pthread_join( thread1, NULL);
pthread_join( thread2, NULL);
pthread_join( thread3, NULL);
pthread_join( thread4, NULL);
pthread_join( thread5, NULL);

printf("Thread 1 returns: %d\n",iret1);
printf("Thread 2 returns: %d\n",iret2);
printf("Thread 3 returns: %d\n",iret3);
printf("Thread 4 returns: %d\n",iret4);
printf("Thread 5 returns: %d\n",iret5);
exit(0);
}

void *alloc_function_two( void *ptr )
{
char *message;
message = (char *) ptr;
void *myblock[COUNT];
int i= 0,j=0;
int freed=0;
printf("message_alloc \n");
while(1)
{
memset(myblock,0,sizeof(myblock));
printf("message_alloc %s \n",message);
for(i=0;i< COUNT ;i++)
{
myblock[i] = (void *) malloc(ALLOC_BYTE);
memset(myblock[i],1, ALLOC_BYTE);
}
}
}


void *alloc_function_one( void *ptr )
{
char *message;
message = (char *) ptr;
void *myblock[COUNT];
int i= 0,j=0;
int freed=0;
printf("message_alloc \n");
while(1)
{
memset(myblock,0,sizeof(myblock));
printf("message_alloc %s \n",message);
for(i=0;i< COUNT ;i++)
{
myblock[i] = (void *) malloc(ALLOC_BYTE);
memset(myblock[i],1, ALLOC_BYTE);
}
}
}

void *alloc_function_three( void *ptr )
{
char *message;
message = (char *) ptr;
void *myblock[COUNT];
int i= 0,j=0;
int freed=0;
printf("message_alloc \n");
while(1)
{
memset(myblock,0,sizeof(myblock));
printf("message_alloc %s \n",message);
for(i=0;i< COUNT ;i++)
{
myblock[i] = (void *) malloc(ALLOC_BYTE);
memset(myblock[i],1, ALLOC_BYTE);
}
}
}
void *alloc_function_four( void *ptr )
{
char *message;
message = (char *) ptr;
void *myblock[COUNT];
int i= 0,j=0;
int freed=0;
printf("message_alloc \n");
while(1)
{
memset(myblock,0,sizeof(myblock));
printf("message_alloc %s \n",message);
for(i=0;i< COUNT ;i++)
{
myblock[i] = (void *) malloc(ALLOC_BYTE);
memset(myblock[i],1, ALLOC_BYTE);
}
}
}
void *alloc_function_five( void *ptr )
{
char *message;
message = (char *) ptr;
void *myblock[COUNT];
int i= 0,j=0;
int freed=0;
printf("message_alloc \n");
while(1)
{
memset(myblock,0,sizeof(myblock));
printf("message_alloc %s \n",message);
for(i=0;i< COUNT ;i++)
{
myblock[i] = (void *) malloc(ALLOC_BYTE);
memset(myblock[i],1, ALLOC_BYTE);
}
}
}