Date: Wed, 11 Sep 1996 19:00:00 -0700 From: "Michael L. VanLoon -- HeadCandy.com" <michaelv@MindBender.serv.net> To: Mark Mayo <mark@quickweb.com> Cc: hackers@freebsd.org Subject: Re: forking program ? Message-ID: <199609120200.TAA23852@MindBender.serv.net> In-Reply-To: Your message of Wed, 11 Sep 96 16:27:15 -0400. <Pine.BSF.3.94.960911162448.25775A-100000@scooter.quickweb.com>
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>I remember some time back someone posted a little piece of code that
>forked and allocated memory until the OS gave up.. and the same program
>appeared with an NT version (using CreateThread instead of fork()).
Appended first is the original article that started the thread.
Appended second is the NT version that I wrote.
You should be able to find anything else by searching the FreeBSD
archives using the information in these two messages...
---------- >8 ----- Begin article ----- 8< ----------
(Message freebsd/hackers:3826)
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id TAA15058; Thu, 8 Aug 1996 19:19:17 GMT
Date: Thu, 8 Aug 1996 22:19:17 +0300 (EET DST)
From: "Litvin Alexander B. <litvin@cmr.kiev.ua>" <archer@cmr.kiev.ua>
To: hackers@freebsd.org
Subject: "Panick" - help needed...
Message-ID: <Pine.BSD/.3.91.960808221623.14971A-100000@cmr.kiev.ua>
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Hello, All!
I was advised by J.K.Habbard to send this into freebsd.hackers, so
here my "problem" goes...
I tried to figure out how would FreeBSD behave under heavy load.
For this purpose I wrote the simple program. It creates 200 copies
of itself, and then each copy tries to give system some work, that
is opens a file and writes into it randomly and also allocates memory,
uses it and frees memory afterwards. Here it is:
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
int main()
{
int incarnation; /* Program incarnation */
int i,j; /* Counters */
int descriptor; /* File descriptor */
int PID,status; /* Self-explaining */
char buffer[512]; /* Buffer for file operations */
int written; /* Bytes written */
char name[10]; /* For file name */
double t; /* Temporary */
char* p=NULL; /* Dinamic allocated memory pointer */
for(incarnation=0;incarnation<200;incarnation++)
{
PID=fork(); /* Let's create another incarnation */
if(PID==-1)
{
printf("Cannot create another process, %d\n",incarnation);
break;
}
if(!PID)
break;
}
sprintf(name,"%d",getpid());
descriptor=open(name,O_CREAT|O_WRONLY,0777); /* Create temporary file */
if(descriptor==-1)
{
printf("Cannot create another file, %d\n",incarnation);
exit(-1);
}
srand(incarnation); /* Make some randomization */
for(i=0;i<1000;i++) /* Do some work */
{
written=write(descriptor,buffer,512);
if(written!=512)
{
printf("Cannot write file, %d\n",incarnation);
close(descriptor);
if(p)
free(p);
exit(-1);
}
/* We'll write into file at random position */
t=((double)rand()/(double)RAND_MAX)*32255.;
lseek(descriptor,(int)t,SEEK_SET);
if(p) /* Use some VM as well */
{
for(j=0;j<0xffff;j++)
p[j]='Z';
free(p);
p=NULL;
}
else
{
p=(char*)malloc(0xffff*sizeof(char));
if(!p)
{
printf("Cannot allocate memory, %d\n",incarnation);
close(descriptor);
exit(-1);
}
for(j=0;j<0xffff;j++)
p[j]='z';
}
}
close(descriptor);
if(p)
free(p);
wait(&status);
return 0;
}
I ran at at one 2.1 box: AMD 5x86-133, ISA/PCI, 24M ram, 1.2G IDE hard
disk, and at two 2.1.5 boxes: Pentium 100, ISA/PCI, 16M ram, Adaptec 7850
SCSI adapter, Seagate 2G SCSI hard disk, and Pentium 75, ISA/PCI, 16M ram,
1.2G hard disk.
Each system crashes with message like:
kernel page directory invalid pdir=0x52e063 va=0xc000
^^^^^^^^
actual numbers may differ
panic: invalid page directory
Crash is more or less severe from time to time. Sometimes system will
work well with 200 processes, but crash with 300 - it depends.
I don't see any reason for such system behaviour. I'm not sure it's
melfunction, but will be grateful to hear any comments. For we would
like to use FreeBSD as a server for http, ftp, nntp, and other
services, and we're very concerned with it's stability. I of course
know that ftp.freebsd.org sustains very heavy load, but...
At least, system should refuse to give servicies when overloaded, but
(from my point of view) it shouldn't crash!
P.S. May be the program is simply buggy - forgive the dummy in that case.
--
Litvin Alexander <archer@cmr.kiev.ua>
+--------------------+
|"Must-die" must die!|
+--------------------+
---------- >8 ----- End article ----- 8< ----------
---------- >8 ----- Begin NT code ----- 8< ----------
(Message carbons:1943)
To: "Ron G. Minnich" <rminnich@sarnoff.com>,
"Litvin Alexander B. <litvin@cmr.kiev.ua>" <archer@cmr.kiev.ua>
cc: hackers@freebsd.org
Subject: Re: "Panick" - help needed...
In-reply-to: Your message of Thu, 08 Aug 96 16:45:42 -0400.
<Pine.SUN.3.91.960808160220.25116I-100000@terra>
Date: Fri, 09 Aug 1996 01:17:55 -0700
From: "Michael L. VanLoon -- HeadCandy.com" <michaelv@MindBender.HeadCandy.com>
>i just tried this on linux 1.3.99 for grins. It does not crash the
>system. It just makes the system totally unusable. X locks up, my 'top'
>window stops updating, etc.
[details of Linux biting for anything other than benchmarks, deleted...]
>If anyone runs this on a freebsd desktop i'd be interested in what you
>observe -- how does interactive response function as this program runs.
>Does the system become unusable for interactive use as does linux or does
>the system just keep plugging along. Same for NT if anyone wants to fool
>with it.
I ran it on my NetBSD system. NetBSD-current (1.2_BETA), AMD 5x86
133MHz, 24MB RAM, BusLogic BT747s EISA SCSI, filesystem on a two SCSI
drive ccd, etc.
It ran for fifteen minutes, approximately with no noticeable
weirdness. Response was *very* sluggish, taking a few minutes to log
into another PCVT virtual terminal. This is probably partially
because 200 processes were writing non-stop on the same disks it was
trying to swap my process back in off of. I have a feeling it would
have responded much quicker if the tmp files were written to a disk
that had none of my swap allocated on it.
At around fifteen minutes, I got a panic: vm_map_entry_create: out of
map entries. Note that this is not exactly a bug. It's just a design
deficiency in the old mach memory system NetBSD still uses.
I. e. pmap entries are allocated in a fixed table, and I just plain
ran out of them. The FreeBSD VM system has an advantage in this
particular area.
I also ran a modified version of this program on NT Server 4.0 Beta 2
(haven't upgraded to the release bits at home, yet), ASUS Pentium
100MHz, BusLogic BT956c PCI SCSI controller, etc.
It ran for twenty minutes straight before I finally killed it.
Absolutely nothing bad happened, as I had expected (we push NT
machines a *lot* harder than this in the Exchange stress labs). The
machine, like NetBSD, was very sluggish while the whole thing was in
progress, taking from 30 to 60 seconds to switch back to a program
that had gotten pushed out to swap. Since the filesystem and the
swap, once again, were on the same drive, that probably was a
significant impact.
Here is my NT version of your program:
--------------------------------------------------------------------
#include <windows.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#define MAX_THREADS 200
int thrash(int iParam)
{
DWORD dwThreadID = 0;
int i, j; /* Counters */
HANDLE hFile;
DWORD dwStatus;
BOOL bRet;
char buffer[512]; /* Buffer for file operations */
int written; /* Bytes written */
char name[256]; /* For file name */
double t; /* Temporary */
char* p = NULL; /* Dinamic allocated memory pointer */
Sleep(rand() * 9000 / RAND_MAX + 1000); // 1 to 10 seconds
printf("Starting thread %d.\n", iParam);
dwThreadID = GetCurrentThreadId();
sprintf(name, "thrasher-tmp-%d", dwThreadID);
hFile = CreateFile(name, GENERIC_WRITE, FILE_SHARE_WRITE, NULL,
CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
if (hFile == INVALID_HANDLE_VALUE)
{
dwStatus = GetLastError();
printf("Cannot create another file, %d: 0x%08x/%d\n", dwThreadID,
dwStatus, dwStatus);
goto Exit;
}
for (i = 0; i < 1000; i++) /* Do some work */
{
bRet = WriteFile(hFile, buffer, 512, &written, NULL);
if (!bRet || written != 512)
{
dwStatus = GetLastError();
printf("Cannot write file, %d: 0x%08x/%d\n", dwThreadID,
dwStatus, dwStatus);
goto Exit;
}
/* We'll write into file at random position */
t = ((double)rand() / (double)RAND_MAX) * 32255.;
dwStatus = SetFilePointer(hFile, (LONG)t, NULL, FILE_BEGIN);
if (dwStatus < 0)
{
dwStatus = GetLastError();
printf("Cannot seek file, %d: 0x%08x/%d\n", dwThreadID,
dwStatus, dwStatus);
goto Exit;
}
/* Use some VM as well */
if (p)
{
for (j = 0; j < 0xffff; j++)
p[j] = (char)j;
free(p);
p = NULL;
}
else
{
p = (char*)malloc(0xffff * sizeof(char));
if (!p)
{
dwStatus = GetLastError();
printf("Cannot allocate memory, %d: 0x%08x/%d\n", dwThreadID,
dwStatus, dwStatus);
goto Exit;
}
for (j = 0; j < 0xffff; j++)
p[j] = ~(char)j;
}
}
dwStatus = 0;
Exit:
if (hFile != INVALID_HANDLE_VALUE)
{
CloseHandle(hFile);
hFile = INVALID_HANDLE_VALUE;
}
if (p)
{
free(p);
p = NULL;
}
return dwStatus;
}
int main()
{
int nThreads;
HANDLE hThread;
DWORD dwStatus;
srand(GetTickCount());
for (nThreads = 0; nThreads < MAX_THREADS; nThreads++)
{
hThread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)thrash,
(LPVOID)nThreads, 0, NULL);
if (hThread == NULL)
{
dwStatus = GetLastError();
printf("Cannot create another thread, %d: 0x%08x/%d\n",
nThreads, dwStatus, dwStatus);
break;
}
}
thrash(nThreads);
return 0;
}
--------------------------------------------------------------------
---------- >8 ----- End NT code ----- 8< ----------
-----------------------------------------------------------------------------
Michael L. VanLoon michaelv@MindBender.serv.net
--< Free your mind and your machine -- NetBSD free un*x >--
NetBSD working ports: 386+PC, Mac 68k, Amiga, Atari 68k, HP300, Sun3,
Sun4/4c/4m, DEC MIPS, DEC Alpha, PC532, VAX, MVME68k, arm32...
NetBSD ports in progress: PICA, others...
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