I have a 12 core Linux cpu but the load is really high on this box, hovering around 50. Post: 302911437

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Top Forums UNIX for Dummies Questions & Answers I have a 12 core Linux cpu but the load is really high on this box, hovering around 50. Post 302911437 by Corona688 on Thursday 31st of July 2014 03:31:38 PM

07-31-2014

Registered User

A single-thread process can't use more than one core -- 100% -- so anything above 100% must have threads. All of them might have threads, just not as busy right now.

I must make this clear: We know nothing of this "zoombie" application. (Searching for it on the net just finds a game for android.) For all I know, this problem might be a bug or misconfiguration, fixed without resorting to anything I suggest next. You should really consult your vendor about this issue before you invest too much time or money.

That said, I see two paths.

1) Configure zoombie to run less threads. People will need to start waiting their turn. How to do this depends on the application in question.

If your disks and memory can't keep up with the load, it doesn't matter how many cores you have. 50 idle cores all waiting for the same disk (which might actually be counted in the load average on Linux) aren't any faster than 30 idle cores.

2) Toughen your system to tolerate such a high load.

A load average of 50 on a 12-core system isn't as horrible as it sounds... It's not great, but it's no worse than 4 on a single-core. Lots of systems (especially leased ones -- getting the most for you money) tolerate quite high loads nonstop.

They deal with it by having lots of memory, beefing up the disks, nice-ing the hungriest processes (so you get priority when you need to administrate), putting swap on a separate hard-disk, and other such things -- this is standard configuration for most large UNIX systems, but not so much for consumer Linux unless they really planned ahead. This reduces the punishment various bottlenecks will cause, so it slows down more or less proportionately instead of bogging down.

You still need to control how fast queries are allowed to happen, though. The total amount of work done per second doesn't improve without more cores, so the more queries you accept, the slower they'll be completed. If your server allows itself to accept more queries per second than it can complete in a second, it's doomed.

Questions for you:

I'd like to see top and ps and iotop sometime your load average is really, really high. If you can't catch it in the act, you might need something like sar to record it.

Last edited by Corona688; 07-31-2014 at 04:53 PM..

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LEARN ABOUT NETBSD

cpuset_set

CPUSET(3)						   BSD Library Functions Manual 						 CPUSET(3)

NAME

     cpuset_create, cpuset_destroy, cpuset_zero, cpuset_set, cpuset_clr, cpuset_isset, cpuset_size -- dynamic CPU sets

SYNOPSIS

     #include <sched.h>

     cpuset_t *
     cpuset_create(void);

     void
     cpuset_destroy(cpuset_t *set);

     void
     cpuset_zero(cpuset_t *set);

     int
     cpuset_set(cpuid_t cpu, cpuset_t *set);

     int
     cpuset_clr(cpuid_t cpu, cpuset_t *set);

     int
     cpuset_isset(cpuid_t cpu, const cpuset_t *set);

     size_t
     cpuset_size(const cpuset_t *set);

DESCRIPTION

     This section describes the functions used to create, set, use and destroy the dynamic CPU sets.

     This API can be used with the POSIX threads, see pthread(3) and affinity(3).

     The ID of the primary CPU in the system is 0.

FUNCTIONS

     cpuset_create()
	      Allocates and initializes a clean CPU-set.  Returns the pointer to the CPU-set, or NULL on failure.

     cpuset_destroy(set)
	      Destroy the CPU-set specified by set.

     cpuset_zero(set)
	      Makes the CPU-set specified by set clean, that is, memory is initialized to zero bytes, and none of the CPUs set.

     cpuset_set(cpu, set)
	      Sets the CPU specified by cpu in set.  Returns zero on success, and -1 if cpu is invalid.

     cpuset_clr(cpu, set)
	      Clears the CPU specified by cpu in the CPU-set set.  Returns zero on success, and -1 if cpu is invalid.

     cpuset_isset(cpu, set)
	      Checks if CPU specified by cpu is set in the CPU-set set.  Returns the positive number if set, zero if not set, and -1 if cpu is
	      invalid.

     cpuset_size(set)
	      Returns the size in bytes of CPU-set specified by set.

SEE ALSO

     affinity(3), pset(3), sched(3), schedctl(8), kcpuset(9)

HISTORY

     The dynamic CPU sets appeared in NetBSD 5.0.

BSD
								 November 2, 2011							       BSD