On 2011-06-01 15.12, Joel Wiramu Pauling wrote:
> Load is generally a measure of a single processor core utilization over an
> kernel dependent time range.
No it isn't. You have totally misunderstood what the load average is.
> Generally as others have pointed out being a very broad (not as in meadow,
> as in continent). Different OS's report load very differently from each
> other today.
That one's sort of correct, although I've yet to see an OS where the load
doesn't in some way refer to an *average* *count* *of* *processes*.
> Traditionally you would see a load average of 1-2 on a multicore system (I
> am talking HP-UX X client servers etc of the early 90's vintage). a Load
> average of 1 means a single core of the system is being utilized close to
> 100% of the time.
No, no, no. Absolutely *NOT*. It doesn't reflect CPU usage at all.
And it never have. The load average must be the single most misunderstood
kernel metric there have ever been in the history of unix systems.
Very simplified it reflects the *number* *of* *processes* in a runnable
state,
averaged over some time. Not necessarily processes actually on core,
mind you,
but the number of processes *wanting* to run.
Now, a process can be in a runnable state for a variety of reasons, and
there
is for example nothing that says it even needs to use up its alloted time
slice when actually running, but it still counts as runnable. It can be
runnable when waiting for a system resource; then it consumes *no* CPU
cycles
at all, but it still counts towards the load average.
> On dual core systems a load average of 1 should be absolutely no cause for
> concern.
I routinely see load averages of 30-40-50, upwards of 100 on some of my
systems. They run absolutely smooth and beautiful, with no noticable lag
or delays. The processors may be near idling, they may be doing some work,
it varies, but it is nothing I can tell from the load average alone.
> Linux has moved away from reporting load average as a percentage of a single
> core time in recent days for precisely this reason, people see a load of 1
> and think there systems are esploding.
>
> In the traditional mold todays processors should in theory get loads of 4-7
> and still be responsive...
I'm sorry to say, but your entire text is based on a misunderstanding of
what
the load average really is, so the above sentences are totally irrelevant.
Regards,
/Benny
> On 31 May 2011 19:10, Joel Carnat <j...@carnat.net> wrote:
>
>> Le 31 mai 2011 ` 08:10, Tony Abernethy a icrit :
>>> Joel Carnat wrote
>>>> well, compared to my previous box, running NetBSD/xen, the same services
>>>> and showing about 0.3-0.6 of load ; I thought a load of 1.21 was quite
>> much.
>>>
>>> Different systems will agree on the spelling of the word load.
>>> That is about as much agreement as you can expect.
>>> Does the 0.3-0.6 really mean 30-60 percent loaded?
>>
>> As far as I understood the counters on my previous nbsd box, 0.3 meant that
>> the
>> cpu was used at 30% of it's total capacity. Then, looking at the sys/user
>> counters,
>> I'd see what kind of things the system was doing.
>>
>>> 1.21 tasks seems kinda low for a multi-tasking system.
>>
>> ok :)
>
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