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I've read some conflicting info. Should I be looking at the smp kernels or the amd64 kernels? Is there much of a performance difference?
My main reason for going dual-core is so I can assign heavy tasks to one cpu while not experiencing much slowdown in other tasks. Would one kernel do this better than the other?
As far as I know, all the kernels except the -486 ones are SMP enabled now in Debian. If you are doing very intensive work, you may get a boost out of compiling your own kernel (aiming it at your processor and changing the default preemption model and timer frequency). But in many cases, the default settings are more than good enough.
Should I be looking at the smp kernels or the amd64 kernels? Is there much of a performance difference?
I think you're effectively asking between a 32bit kernel with smp support and a 64bit kernel with smp support.
The amount of performance difference very much depends on the type of programs you are running. But usually not much difference.
Quote:
My main reason for going dual-core is so I can assign heavy tasks to one cpu while not experiencing much slowdown in other tasks. Would one kernel do this better than the other?
Comparing 32bit vs 64bit kernels, there should be no difference in your ability to limit the heavy tasks in order to keep the high priority tasks responsive.
Forcing all the "heavy" tasks onto one core is a fair amount of effort and not necessarily a great approach for your intended purpose (but equally hard and equally effective for 32 bit vs 64 bit). Most likely almost all the responsiveness benefit you could have gotten by that restriction is available just from having dual core and setting lower priority for the "heavy" tasks.
Almost all Linux kernels do not prioritize memory use according to cpu priority. So if your "heavy" tasks are heavy in memory use, they may make your high priority tasks very non responsive regardless of strategies such as limiting them to a single core or lowering their priority, etc. That can be a hard problem to solve (short of simply having more physical ram than your heavy tasks use).
If those heavy tasks do a lot of file I/O as well, they may fill ram with file caching, again making high priority tasks less efficient. If that is an issue, you can reduce the value of "swappiness" to reduce the file caching (and performance) of tasks that do a lot of file I/O in favor of responsiveness of tasks that don't do a lot of file I/O.
So, are there any reasons to go with one rather than the other (32 bit versus 64) since both have smp support? Will 32 bit software run on the 64 bit kernel if I can't find a 64bit version?
Will 32 bit software run on the 64 bit kernel if I can't find a 64bit version?
Not being able to find a 64bit version is very rare. But if you're worried about that:
Most AMD64 Linux distributions include support for running 32bit applications. That feature is generally called "multi-lib". If the distribution says the AMD64 variant is "multi-lib", it supports 32-bit as well. If it doesn't say, it probably still supports 32bit as well (but you might want to ask).
Many 32bit applications will require that you install some extra 32bit support packages that aren't part of base install of the distribution and may not have an obvious name relative to the listed dependencies of that 32bit application. But the problem usually isn't hard to solve.
In Debian based distributions, in worst case, you can fall back on trying the application and seeing which file is missing, then use either apt-file or a convenient web page within the Ubuntu site (don't have the URL handy) that tells you which Debian packages have a specific file. (Then install that package and try again, usually finding another package you need next).
In Red Hat based distributions, that process is a little different, but probably not harder.
Distribution: Debian lenny & squeeze servers. Mint 13 and 14 desktops
Posts: 16
Rep:
I tried the AMD64 on this dual core celeron..but frankly the messiness of dragging in 32 bit support libraries some of which didn't seem to exist..wore me down, and I went 32bit.
I think if you want an easy life, stay 32 bit for now. It plays nice with the twin cores Most 3rd party stuff out there is 32 bit still..
If you want to play and spend time getting awkward stuff working, try the 64..
64bits mostly make sense if you want to use more than 2-3G memory. 32bit apps can only address up to 2G, 32bit kernels usually either 4 or 64G (depending on if PAE is enabled). Debian & ubuntu (5.0 & 8.04) default to 4G. 64bit apps and 64bit kernel address a lot more (2^64 bits), your motherboard is the limit.
About the apps, the only significant missing app in my opinion is the java plugin for browsers. Obviously there are more stuff, e.g. I just learned secondlife only exists in 32bit version.
64bits mostly make sense if you want to use more than 2-3G memory. 32bit apps can only address up to 2G, 32bit kernels usually either 4 or 64G (depending on if PAE is enabled). Debian & ubuntu (5.0 & 8.04) default to 4G. 64bit apps and 64bit kernel address a lot more (2^64 bits), your motherboard is the limit.
About the apps, the only significant missing app in my opinion is the java plugin for browsers. Obviously there are more stuff, e.g. I just learned secondlife only exists in 32bit version.
64bit java exists. 64bit java plugin??? I haven't heard of that. Do you use 32-bit plugin or is full 64bit plugin out?
Code:
siim@Shiva:~$ LC_ALL="C" dpkg -l sun-java*
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Cfg-files/Unpacked/Failed-cfg/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Hold/Reinst-required/X=both-problems (Status,Err: uppercase=bad)
||/ Name Version Description
+++-============================-============================-========================================================================
un sun-java5-jre <none> (no description available)
ii sun-java6-bin 6-10-0ubuntu2 Sun Java(TM) Runtime Environment (JRE) 6 (architecture dependent files)
un sun-java6-demo <none> (no description available)
un sun-java6-doc <none> (no description available)
ii sun-java6-fonts 6-10-0ubuntu2 Lucida TrueType fonts (from the Sun JRE)
ii sun-java6-jdk 6-10-0ubuntu2 Sun Java(TM) Development Kit (JDK) 6
ii sun-java6-jre 6-10-0ubuntu2 Sun Java(TM) Runtime Environment (JRE) 6 (architecture independent files
un sun-java6-jre-headless <none> (no description available)
un sun-java6-plugin <none> (no description available)
un sun-java6-source <none> (no description available)
Code:
siim@Shiva:~$ sudo apt-get install sun-java6-plugin
[sudo] password for siim:
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package sun-java6-plugin is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package sun-java6-plugin has no installation candidate
Code:
siim@Shiva:~$ uname -a
Linux Shiva 2.6.27-11-generic #1 SMP Thu Jan 29 19:28:32 UTC 2009 x86_64 GNU/Linux
I couldn't find the plugin at the link the trooper posted. But the debian version was easy to install.
Thanks!
Ott
That's because the link was not for a Ubuntu flashplugin.
Quote:
This is Ubuntu 8.10.
Why use a Debian package?
If you want to risk using Debian packages in Ubuntu that's up to you.
I took the time to Google the Ubuntu version,it's in Jaunty:
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