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  #1  
Old 21st September 2006, 03:00 AM
qinhan Offline
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what is avahi-daemon?

Just noticed it's taking more than 50% of the cpu usage constantly. What is it doing?
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  #2  
Old 21st September 2006, 03:25 AM
dishawjp Offline
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Check this link out. If you don't use it, kill it. I did, but then I don't have a laptop.

http://avahi.org/

HTH,

Jim Dishaw
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  #3  
Old 21st September 2006, 03:43 AM
Iron_Mike Offline
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Not necessarily for a laptop that was just an example. It is a dynamic discovery program that when a computer is plugged into an existing can go out and show printers, hosts, scanners on the network providing security allows it so.
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Old 21st September 2006, 03:56 AM
dishawjp Offline
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Quote:
Not necessarily for a laptop
Agreed, however *most* desktops don't have to go out and find printers, scanners and etc. after initial installation and kudzu does a decent job of detecting new hardware attached directly to the computer.

Anyway, my point was (is), if he doesn't know what it is and he's not using a laptop (or isn't connected to some sort of a dynamic network which is highly unlikely), then he probably doesn't need it and can safely stop the service.

But that's just my opinion. I gave him a URL to read and he can decide for himself.

Jim
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  #5  
Old 21st September 2006, 04:22 AM
Iron_Mike Offline
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Quote:
Originally Posted by dishawjp
Agreed, however *most* desktops don't have to go out and find printers, scanners and etc. after initial installation and kudzu does a decent job of detecting new hardware attached directly to the computer.

Anyway, my point was (is), if he doesn't know what it is and he's not using a laptop (or isn't connected to some sort of a dynamic network which is highly unlikely), then he probably doesn't need it and can safely stop the service.

But that's just my opinion. I gave him a URL to read and he can decide for himself.

Jim
And I totally concur as I have it disabled also but to regulate it laptops is misleading, who knows you might roll a desktop around at work.... All it does is start broadcasting arps to see what is on the network and to see what's available on the network. Now in a secure world as soon as your plug an unknown device in, it will block it. But like you said, give him the info and let him make his own decision.
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  #6  
Old 13th August 2012, 12:54 AM
RogerOdle2 Offline
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Re: what is avahi-daemon?

Why is avahi a daemon that runs all the time and not an on-demand only feature? It discovers network services? Why do I want that unless I am actively looking from one like when I am adding a printer or connecting to a printer? If I am not printing then I do not want my computer looking for a printer. I go days at a time without printing anything. My computer stands alone on my "home" network. What is there to discover anyway? I have been disabling it because it has caused strange problems but that is besides the point.

So what is the purpose of implementing avahi as a daemon service? I would like to know why this decision was made.
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  #7  
Old 13th August 2012, 02:25 AM
smr54 Online
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Re: what is avahi-daemon?

Because Fedora--no, because just about every version of Linux--seems to have forgotten the sysadmins who made it popular. Just about all of them have cpu scaling, avahi, GUI logins and so on as the default. It's aggravating--whether it's lack of competence on developers' part, or the fact that they're a bunch of durn kids on my lawn who haven't ever had to administer more than their moms' basement (had to throw that in--and please DO keep in mind that I'm relatively old and a great many of my complaints are just sour grapes of an old guy).

It's getting to the point where it's becoming as, or more difficult to go against the developers' decisions for you than it is with Windows. Hrrm, I'm sure I'm exaggerating, or only talking about one isolated thing, but being reasonable takes all the fun out of it, so NO MORE BEING REASONABLE, durn young kids!!!

Seriously, it is problematic in some cases. Many of the decisions have people, who are apparently very skilled programmers but either ignorant or uncaring of the sysadmin's thoughts, and will say things like it's not a big deal if the system doesn't get the time at boot, or the famous I don't really care how Unix has done things for 40 years. (Which made the front page of slashdot and made so much news that that particular decision was changed.)

HOWEVER--and I think this is important, IMHO. The distributions that do this, e.g., Fedora, Ubuntu, and company are far more popular and widely used than the ones that don't, such as Arch, or the BSDs (which isn't a distribution, it's an alternative Unix like system). So, these choices may, for the sake of the distribution, be the right choice. Just because I hate it doesn't mean it's bad.

While one could argue well, they'll see when people drop RH in the Enterprise--because, it's not gonna happen, in the same way that regardless of how Windows aggravates people, most businesses aren't going to take the trouble to re-educate their entire workstation rollout, and most businesses that are using RH as servers, while they might get aggravated, aren't going to change it.

What would be interesting, but I doubt it will happen, would be if one of the binary compatible versions, CentOS, SL, or even Oracle, worked around these various newer user oriented distros, and suddenly took off in popularity.
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  #8  
Old 13th August 2012, 01:15 PM
secipolla Offline
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Re: what is avahi-daemon?

I don't know if it adds to the discussion. I don't need that either but I have it installed because gvfs 'requires' it.
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  #9  
Old 13th August 2012, 01:48 PM
smr54 Online
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Re: what is avahi-daemon?

Yes, if you try to remove it, a great many gnome packages go with it, as well others that don't really need it.
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  #10  
Old 20th August 2012, 01:28 AM
RogerOdle2 Offline
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Re: what is avahi-daemon?

Like sendmail, it is a service that I always disable. I have had several mysterious system slow down where I have found avahi consuming large amounts of CPU time. I do not no what it was doing. The description of what it is supposed to accomplsh is something that I would only want to run when I asked for it. The marginal bennifit of "learning" the environment before I ask for something is not justified. Especially in a home environment that rarely changes. How often do you replace a printer?

I have found that startup to my desktop is often delayed by backgound services that have little or nothing to do with the desktop. Like the NFS server. I have found in the past that some minor error in NFS configuration caused it to stall during startup and delay bringing up the desktop for several minutes. All of the desktop distros could make a better effort of separating server related startup issues from desktop ones. I know some of you think that a desktop should never be running services in the first place except some of these are installed as dependencies and developers are going to run services on desktops for test purposes anyway.

I use an apache server as a portable mirror server for Fedora because I have to maintain several computers in a lab environment. Fedora does not install an NFS client by default. It is convenient to accesss the few configuration changes from the web server then use yum update to finish installation and then complete a standard install on each of the lab machines. This is a convenience that a server application provides for workstation. You can not count on smb or nfs clients to be available but you can almost always expect to find a web browser application.

So you are going to find servers frequently installed on desktops. The systems need to be configured to give priority to bringing the desktop to some basic level of performance independant of non-desktop related services. If something is not part of the desktop then it should not be in the execution thread for activating the desktop. Even if a desktop gadget may require such a service, access to that service should never be essential and startup for the desktop should not pause for a moment for some gadget to access some service. In fact, the desktop should not depend on any service (other that X) in order to bring up a desktop with file and terminal access sufficient for system maintenence.
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  #11  
Old 20th August 2012, 04:17 PM
stevea Offline
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Re: what is avahi-daemon?

Avahi used to be enabled and configured in some of the older Fedoras. I think around FC8 I setup my LAN to use Avahi for a day, just for grins. Then it ceased to work well and was default disabled in Fedora. Then more recently it's default "ON" service, returns like a bad penny. I'd classify Avahi as "mostly useless". It's a pretty wimpy way to configure a LAN and if you have a router w/ DHCP service that's a lot more functional.

If your LAN isn't configured for Avahi and you don't have a network appliance, like an Apple printer, using Avahi then you don't need it. Its a free implementation of the Apple zeroconf LAN configuration idea. The reason the daemon always run is that it must always listen for identification packets. Still it's should not use any CPU time of note. If yours is eating CPU time you should submit a bugzilla report.

Avahi is another Lenart Poetteing idea - like Pulse audio and systemd. These aren't bad ideas at all, but the implementation of each one has been a big headache. So submitting a bugzilla report that Lenart must address is a good way to slow/prevent the next 'Poetteing invention' from causing havoc.
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Last edited by stevea; 20th August 2012 at 04:27 PM.
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  #12  
Old 20th August 2012, 04:34 PM
Dutchy Offline
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Re: what is avahi-daemon?

Quote:
Avahi is another Lenart Poetteing idea - like Pulse audio and systemd
Not solely Lenart's idea but okay.
Pulseaudio and avahi together makes a nice remote audio system possible.
As the network brings more and more services it is nice to have an automatic solution like Avahi (but to some people it seems like an unnecessary service, on a server I agree to that, but not on a desktop/laptop).

Anyway, this thread is more than six years old so way dig it up again?
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Old 24th August 2012, 08:26 AM
RogerOdle2 Offline
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Re: what is avahi-daemon?

Why do you think that your computer is the one that has to be "on" all the time. It is the printer that needs to be on all the time and listening for hosts that are searching for printers. Your computer should never waste CPU cycles listening for such devices. It is a waste of CPU cycles and network bandwidth.

It would be better implemented along the lines of ARP. Your computer would broadcast on the local network "who is a printer" and printers would answer back "I am a printer at IP at address x.x.x.x" then your computer would query the printer for details. This would only happen when you add a printer. If you added a printer before then your computer would assume that the printer was still at the same address the next time you wanted to print and would only do the discovery job when needed. This kind of "learn the network when needed" would simplify the normal run time. Avahi wouldn't clutter the process schedule with uneeded tasks because it would not run at all unless that user had a specific and immediate need for it.

Another candidate for this treatment is CUPS. If you are not sharing your printer on the network then you have no need for a persistent printer server. This should run only when there are scheduled print jobs and terminate immediately when the last print job is completed. My printer lives on eithernet and has it's own internal print server. I have no need to run a print server out of my own computer.

I get a faster computer because I want to get my job done faster. I don't get one just because I want my computer to run as fast as it did last year only because the vendors decided that I didn't really need all that process power anyway and took it as an excuse to deliver substandard software. Few programmers today spend any time at all considering the performance impact of the programs they write. They figure that the user can just compensate by throwing money at the problems they create by getting more memory and faster processors. What is the result? We have computers that are an order of magnitude faster that run systems that are an order of magnitude sloppier. The performance has certainly not increased as much as the "improved" hardware promised.

How do you clean up the overall design? Before implementing any given service, consider how it relates to the work pattern of the user. If the user seldom uses it or only biefly uses it then it should be an on-demand type of service and not a persistent one. Xinetd provided a mechanism for on-demand type services. I seem to remember that there was criticism for security concerns but I don't remember what they were. I can't imagine what, if any, security problems would be unique to on-demand operation as opposed to persistent always-online operation. I would suppose that these security concerns related to the particular design of Xinetd and not to the concepts behind it. This approach was intended to make servers more efficient and provided for more CPU scheduled time for high demand services on server machines. It doesn't really fit the common data-center server design today but if seems worth considering for desktop systems that run "services" as background tasks that provided little value most of the time. My point is that the persistent server problem was solved long ago for good reasons. These reasons have not gone away just because we can get faster processors today.
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Old 24th August 2012, 10:42 AM
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Re: what is avahi-daemon?

Quote:
Originally Posted by Dutchy View Post
Not solely Lenart's idea but okay.
Zeroconf is the Apple scheme and Avahi is the Poettering & Lloyd free version. BFD.

Quote:
Pulseaudio and avahi together makes a nice remote audio system possible.
As the network brings more and more services it is nice to have an automatic solution like Avahi (but to some people it seems like an unnecessary service, on a server I agree to that, but not on a desktop/laptop).
avahi/zeroconf makes no sense unless it's used by several or all services on your LAN. I can barely parse your idea - your net-printer is a server and your pulse-sink is a server your file-server is a server and these are exactly the things that you would want to run avahi - if you like that flavor of networking. Of course you don't NEED avahi for these.

Avahi/zeroconf seems to have a lot of unaddressable security issues. I don't worry so much on a home LAN behind a firewall but .... There are a lot of other ideas for service identification and several RFCs. I'd prefer something that isn't chattering all the time.


Quote:
Anyway, this thread is more than six years old so way dig it up again?
Not me chum(), that was RogerOdle2 that rekindled.






Quote:
Originally Posted by RogerOdle2 View Post
Why do you think that your computer is the one that has to be "on" all the time. It is the printer that needs to be on all the time and listening for hosts that are searching for printers. Your computer should never waste CPU cycles listening for such devices. It is a waste of CPU cycles and network bandwidth.
In Avahi service discovery the printer, for example, is periodically sending out service advertisement packets. You connect your laptop/desktop and it listens for the service advertisements to figure out where the services are. I seem to recall there is some non-multicast way do service discovery, too.


Quote:
It would be better implemented along the lines of ARP. Your computer would broadcast on the local network "who is a printer" and printers would answer back "I am a printer at IP at address x.x.x.x" then your computer would query the printer for details.
Yes. And there are protocols to do exactly that. You are right that you'd only need to inquire for a service when needed and that could be through a library call rather than a listening process on the client..

Quote:
Another candidate for this treatment is CUPS. If you are not sharing your printer on the network then you have no need for a persistent printer server. This should run only when there are scheduled print jobs and terminate immediately when the last print job is completed. My printer lives on eithernet and has it's own internal print server. I have no need to run a print server out of my own computer.
Yes, I agree. Good example. But thats not a print server per se, its a scheduler/listener.. You can configure your client cupsd to use 'cups-polld' but that generates even more traffic (periodic polls by every client!).



Quote:
I get a faster computer because I want to get my job done faster. I don't get one just because I want my computer to run as fast as it did last year only because the vendors decided that I didn't really need all that process power anyway and took it as an excuse to deliver substandard software. ...
Now you are off in the weeds. The cost of a process listening is extremely low (some memory occupancy, no CPU cycles). Your client Avahi is somehow broken if it's using any substantial CPU time. This is not by design - it's a bug.

I tend to agree with your argument that avahi/zeroconf is not a great design. It was meant to support small home networks where the overheat traffic is ignorable and security was not an issue. It also makes a lot more sense (to me) for clients to initiate service discovery on an as-needed basis via an authenticated service. Distributed is fine, even good. CPU load is not an issue either way if the bugs are gone.
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  #15  
Old 25th August 2012, 04:54 AM
RogerOdle2 Offline
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Re: what is avahi-daemon?

I am not out in the weeds when the reality sits before me. A computer that is ten times faster than the one that I had ten years ago is not getting things done ten times faster. Yes it is doing more things for me. Some times I think that if it does just one more thing for me it will be a brick. There is such a thing as too much help.

I know. Someone is going to come up with a server that answers my email for me, the surfs the web for me, and even finishes those levels on those video games that I just can't quite get. Then I won't have to worry about it. The server can even complain about not getting enough CPU time.
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