Mailinglist Archive: opensuse (3605 mails)
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RE: [SLE] how can I interprate this: cpu use is low, system is fine, loadaverage is high
- From: 张韡武 <zhangweiwu@xxxxxxxxxx>
- Date: Fri, 23 Jun 2006 15:21:49 +0800
- Message-id: <1151047309.6852.4.camel@xxxxxxxxxx>
Sorry for last empty mail went out by accident.
Today someone rebooted the X terminal server in the morning, now it is
in the afternoon, for the whole day 2 users are working on it, doing
exactly the same thing they did yesterday, the load average is....
surprising, 0.33
Basically, the system looks exactly the same, feels as fast as yeserday,
only figures are treating me. Yeserday load average is 8, today is 0.33,
everything was almost the same except the figures.
在 2006-06-22四的 16:53 +0800，张韡武写道：
> 在 2006-06-21三的 11:29 -0400，Marlier, Ian写道：
> >
> > > -----Original Message-----
> > > From: 张|武 [mailto:zhangweiwu@xxxxxxxxxx]
> > > Sent: Wednesday, June 21, 2006 8:44 AM
> > > To: suse-linux-e@xxxxxxxx
> > > Cc: wangpenghui@xxxxxxxxxx
> > > Subject: [SLE] how can I interprate this: cpu use is low, system is fine,
> > > loadaverage is high
> > >
> > > Hello. I just logged in an X terminal server, noticed this X terminal
> > > server has 3 users using it at the same time, one user is developing a
> > > php application using Jedit (apache runs on anther host, he only use the
> > > editor), I am writing email and browsing, the third guy is browsing the
> > > web. The CPU usage is some 0% to 80%, avaragly looks like 10%. The
> > > memory is used 94% (1GB ram), swap space almost not used at all, and
> > > load average is 5.5
> > >
> > > I learned early years in some articles saying load average is the number
> > > of resource competiting for resource, a load average of 3 indicates the
> > > system is under heavy load, a load average of 6 shows the system must be
> > > upgraded or remove some service.
> > >
> > > I don't understand why, when I can see the CPU usage is only 10%, the
> > > load average says the system is under heavy burden. That doesn't make
> > > sense. All the applications, evolution, OpenOffice, chat software,
> > > Firefox... perform just like as fast as if I am the only one using the
> > > computer. Is my feeling cheating me?
> > >
> > > Or, can I interprate the load average of 5.5 as a OK value for X
> > > terminal system? Does desktop application works in different way then
> > > server application? Can this server handle more user by simply adding
> > > more memory bank?
> >
> > Remember that load average doesn't scale according to the number of cores available. A load of 3.0 on a machine with a single dual-core chip is just over half of the effective load of 3.0 on a machine with a single single-core chip. (Not exactly half because of throughput overhead.)
>
> > Load average is the average number of threads waiting at any given time. In the past, they were generally waiting for CPU. We've gotten to the point in CPU development, though, where it seems that waiting for I/O channel space is getting to be common.
> >
> > I've seen load spikes (without associated CPU use jumps) on a number of machines lately; in each case, the root cause has turned out to be backups in the I/O channel.
> >
> > Worth checking into, at least...
>
> Since you mensioned this could be I/O blocking, this is my environment
> and test data today:
>
> 1. 3 user use the X terminal server the same time;
> 2. average CPU usage is lower then 10%;
> 3. memory is used 95%, swap almost not used;
> 4. this is a single-core server;
> 5. I monitored HDD activity using gnome panel resource monitor, it
> shows the HDD activity is very low, almost no activity
> 6. the system behave sanely and fast, opening openoffice less then
> 7 seconds (as it was with one user), doing everything thing
> won't feel being slow
> 7. the only network service this machine have is 'svn', which is
> used very in-frequently
> 8. load average currently is 8.5. It has been higher then 7 since
> the early morning, now it's 17:00
> 9. I cannot understand 8).
>
> Anyone please teach me something new:)
>
> Is the 'load average' something really not for a dynamic system like X
> terminal server? I mean, it can happen that when I open email software,
> someone just hit 'gvim' and pressed enter, and two process compete for
> CPU. This may only happen for 0.5 second, but that also counts. Such
> accident can happen 100 times without user getting noticed, each time
> lasts 0.5 seconds. and because it happened 100 times, it is counted for
> the computer: "in last 5 minutes, process compete for resource 100
> times, thus your computer must be under huge burden and let's give you a
> surprising load-average"
--
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Today someone rebooted the X terminal server in the morning, now it is
in the afternoon, for the whole day 2 users are working on it, doing
exactly the same thing they did yesterday, the load average is....
surprising, 0.33
Basically, the system looks exactly the same, feels as fast as yeserday,
only figures are treating me. Yeserday load average is 8, today is 0.33,
everything was almost the same except the figures.
在 2006-06-22四的 16:53 +0800，张韡武写道：
> 在 2006-06-21三的 11:29 -0400，Marlier, Ian写道：
> >
> > > -----Original Message-----
> > > From: 张|武 [mailto:zhangweiwu@xxxxxxxxxx]
> > > Sent: Wednesday, June 21, 2006 8:44 AM
> > > To: suse-linux-e@xxxxxxxx
> > > Cc: wangpenghui@xxxxxxxxxx
> > > Subject: [SLE] how can I interprate this: cpu use is low, system is fine,
> > > loadaverage is high
> > >
> > > Hello. I just logged in an X terminal server, noticed this X terminal
> > > server has 3 users using it at the same time, one user is developing a
> > > php application using Jedit (apache runs on anther host, he only use the
> > > editor), I am writing email and browsing, the third guy is browsing the
> > > web. The CPU usage is some 0% to 80%, avaragly looks like 10%. The
> > > memory is used 94% (1GB ram), swap space almost not used at all, and
> > > load average is 5.5
> > >
> > > I learned early years in some articles saying load average is the number
> > > of resource competiting for resource, a load average of 3 indicates the
> > > system is under heavy load, a load average of 6 shows the system must be
> > > upgraded or remove some service.
> > >
> > > I don't understand why, when I can see the CPU usage is only 10%, the
> > > load average says the system is under heavy burden. That doesn't make
> > > sense. All the applications, evolution, OpenOffice, chat software,
> > > Firefox... perform just like as fast as if I am the only one using the
> > > computer. Is my feeling cheating me?
> > >
> > > Or, can I interprate the load average of 5.5 as a OK value for X
> > > terminal system? Does desktop application works in different way then
> > > server application? Can this server handle more user by simply adding
> > > more memory bank?
> >
> > Remember that load average doesn't scale according to the number of cores available. A load of 3.0 on a machine with a single dual-core chip is just over half of the effective load of 3.0 on a machine with a single single-core chip. (Not exactly half because of throughput overhead.)
>
> > Load average is the average number of threads waiting at any given time. In the past, they were generally waiting for CPU. We've gotten to the point in CPU development, though, where it seems that waiting for I/O channel space is getting to be common.
> >
> > I've seen load spikes (without associated CPU use jumps) on a number of machines lately; in each case, the root cause has turned out to be backups in the I/O channel.
> >
> > Worth checking into, at least...
>
> Since you mensioned this could be I/O blocking, this is my environment
> and test data today:
>
> 1. 3 user use the X terminal server the same time;
> 2. average CPU usage is lower then 10%;
> 3. memory is used 95%, swap almost not used;
> 4. this is a single-core server;
> 5. I monitored HDD activity using gnome panel resource monitor, it
> shows the HDD activity is very low, almost no activity
> 6. the system behave sanely and fast, opening openoffice less then
> 7 seconds (as it was with one user), doing everything thing
> won't feel being slow
> 7. the only network service this machine have is 'svn', which is
> used very in-frequently
> 8. load average currently is 8.5. It has been higher then 7 since
> the early morning, now it's 17:00
> 9. I cannot understand 8).
>
> Anyone please teach me something new:)
>
> Is the 'load average' something really not for a dynamic system like X
> terminal server? I mean, it can happen that when I open email software,
> someone just hit 'gvim' and pressed enter, and two process compete for
> CPU. This may only happen for 0.5 second, but that also counts. Such
> accident can happen 100 times without user getting noticed, each time
> lasts 0.5 seconds. and because it happened 100 times, it is counted for
> the computer: "in last 5 minutes, process compete for resource 100
> times, thus your computer must be under huge burden and let's give you a
> surprising load-average"
--
Check the headers for your unsubscription address
For additional commands send e-mail to suse-linux-e-help@xxxxxxxx
Also check the archives at http://lists.suse.com
Please read the FAQs: suse-linux-e-faq@xxxxxxxx
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