Another take on /proc statistics (joke of the day)

1999-07-15 Thread Ronald G. Minnich 
I thought this amusing. 

Take the following program, designed to suck stats out of /proc for the
network devices:

#include 
#include 
#include 

main()
{
  char stuff[4096];
  int fd = open("/proc/net/dev", 0);

  while(1)
{
  int amount = read(fd, stuff, sizeof(stuff));
  if (amount > 0)
write(1, stuff, amount);
  sleep(1);
  lseek(fd, (off_t) 0, SEEK_SET);
}

}

Run this on linux, and you'll get the same values for all the stats. 

how to make it work right? 

#include 
#include 
#include 

main()
{
  char stuff[4096];

  while(1)
{
  int fd = open("/proc/net/dev", 0);
  int amount;
  amount = read(fd, stuff, sizeof(stuff));
  if (amount > 0)
write(1, stuff, amount);
  close(fd);
  sleep(1);
}
  
}

What are the implications of this? Well, if you have an rstatd that uses
/proc for statistics, it will have to (for every request)  open the status
files, read them, and close them. Net result: very very poor performance
for an rstatd (not even counting the fact that the rstatd has to parse
formatted output back to a binary format ...)

ron
p.s. the rstatd I have for redhat does indeed read stats out of /proc ...




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Another take on /proc statistics (joke of the day)

1999-07-15 Thread Ronald G. Minnich 

I thought this amusing. 

Take the following program, designed to suck stats out of /proc for the
network devices:

#include 
#include 
#include 

main()
{
  char stuff[4096];
  int fd = open("/proc/net/dev", 0);

  while(1)
{
  int amount = read(fd, stuff, sizeof(stuff));
  if (amount > 0)
write(1, stuff, amount);
  sleep(1);
  lseek(fd, (off_t) 0, SEEK_SET);
}

}

Run this on linux, and you'll get the same values for all the stats. 

how to make it work right? 

#include 
#include 
#include 

main()
{
  char stuff[4096];

  while(1)
{
  int fd = open("/proc/net/dev", 0);
  int amount;
  amount = read(fd, stuff, sizeof(stuff));
  if (amount > 0)
write(1, stuff, amount);
  close(fd);
  sleep(1);
}
  
}

What are the implications of this? Well, if you have an rstatd that uses
/proc for statistics, it will have to (for every request)  open the status
files, read them, and close them. Net result: very very poor performance
for an rstatd (not even counting the fact that the rstatd has to parse
formatted output back to a binary format ...)

ron
p.s. the rstatd I have for redhat does indeed read stats out of /proc ...




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