From: <at...@ne...> - 2002-12-06 13:21:11
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Hello, I looked at some mail subjects in the archives, but found nothing about my question: - how stable is UML for production systems? - how many UMLs can be run in a PC server with about P4 2GHz, 500MB RAM, where the host machine has only one job: running UMLs, and the UMLs will not have high loads (can it handle about 20?) - will the host OS cache the filesystems of the UMLs or it accesses them a more RAM economic way? (some of the UMLs could have 3-5 GB of filesystem) - are there any performance analysis? (for example comparing with freebsd jail) if the answers can be found somewhere, please let me know the urls or some very specific keywords :-) thank you very much, attila |
From: Net L. <net...@li...> - 2002-12-06 15:00:47
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On Fri, 6 Dec 2002, [ISO-8859-2] Bogn=E1r Attila wrote: > Hello, > > I looked at some mail subjects in the archives, but found nothing about > my question: > > - how stable is UML for production systems? Stable enough for me. I run two UML production servers with apache, exim, & cvs in them. > - how many UMLs can be run in a PC server with about P4 2GHz, 500MB RAM, > where the host machine has only one job: running UMLs, and the UMLs will > not have high loads (can it handle about 20?) RAM is the limiting factor for UML. 500MB will *never* be sufficient for more than 4 or 5 simultaneous UML's. > - will the host OS cache the filesystems of the UMLs or it accesses them > a more RAM economic way? (some of the UMLs could have 3-5 GB of filesyste= m) cache the filesystem? You can use tempfs for the memory that you allocate to each UML, however the actual filesystem is on disk. Seeing as how you only have 500MB of RAM, how did you expect to cache 3-5GB of filesystems?? > - are there any performance analysis? (for example comparing with > freebsd jail) I dont' know. Someone else will have to answer this one. > if the answers can be found somewhere, please let me know the urls or > some very specific keywords :-) Well there is http://user-mode-linux.sf.net --=20 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Lonni J Friedman=09=09=09=09n...@li... Linux Step-by-step & TyGeMo=09=09 http://netllama.ipfox.com |
From: <at...@ne...> - 2002-12-06 17:48:04
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>>- will the host OS cache the filesystems of the UMLs or it accesses them >>a more RAM economic way? (some of the UMLs could have 3-5 GB of filesystem) > > > cache the filesystem? You can use tempfs for the memory that you allocate > to each UML, however the actual filesystem is on disk. Seeing as how you > only have 500MB of RAM, how did you expect to cache 3-5GB of filesystems?? well, I asked this because I do not want to cache it - in another way: is there a possibility to avoid caching them (putting every UML on another partition is not a solution, maybe if the UML uses a part of the original filesystem). >>if the answers can be found somewhere, please let me know the urls or >>some very specific keywords :-) > > > Well there is http://user-mode-linux.sf.net I found this list on that one ;-) I read some part of it, but if UML does not fit to my needs, I don't want to spend hours/days on reading about it and testing. I am grateful for every answer. attila |
From: Net L. <net...@li...> - 2002-12-06 17:57:24
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On Fri, 6 Dec 2002, [ISO-8859-2] Bogn=E1r Attila wrote: > >>- will the host OS cache the filesystems of the UMLs or it accesses the= m > >>a more RAM economic way? (some of the UMLs could have 3-5 GB of filesys= tem) > > > > > > cache the filesystem? You can use tempfs for the memory that you alloc= ate > > to each UML, however the actual filesystem is on disk. Seeing as how y= ou > > only have 500MB of RAM, how did you expect to cache 3-5GB of filesystem= s?? > > well, I asked this because I do not want to cache it - in another way: > is there a possibility to avoid caching them (putting every UML on > another partition is not a solution, maybe if the UML uses a part of the > original filesystem). Either i'm not understanding what you're trying to do, or you don't understand how UML works. I don't see what partitions have to do with this at all. > >>if the answers can be found somewhere, please let me know the urls or > >>some very specific keywords :-) > > > > > > Well there is http://user-mode-linux.sf.net > > I found this list on that one ;-) I read some part of it, but if UML > does not fit to my needs, I don't want to spend hours/days on reading > about it and testing. I am grateful for every answer. So basically you don't want to read documentation? I'm not sure that even Linux is for you if you're not willing to put in some time reading dox. UML is not something that you're going to understand in under an hour. --=20 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Lonni J Friedman=09=09=09=09n...@li... Linux Step-by-step & TyGeMo=09=09 http://netllama.ipfox.com |
From: <at...@ne...> - 2002-12-06 18:29:45
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>> >>- will the host OS cache the filesystems of the UMLs or it accesses >> them a more RAM economic way? (some of the UMLs could have 3-5 GB of >> filesystem) >> > >> > >> > cache the filesystem? You can use tempfs for the memory that you >> allocate to each UML, however the actual filesystem is on disk. >> Seeing as how you only have 500MB of RAM, how did you expect to >> cache 3-5GB of filesystems?? >> >> well, I asked this because I do not want to cache it - in another way: >> is there a possibility to avoid caching them (putting every UML on >> another partition is not a solution, maybe if the UML uses a part of >> the original filesystem). > > Either i'm not understanding what you're trying to do, or you don't > understand how UML works. I don't see what partitions have to do with > this at all. You're right, I don't fully understand how UML works. But every product has a purpose and every product has some properties that can be summarized and thus it is possible to decide whether it is possible that it fits your need or not. If it seems that it can fulfill my needs, than I will read every documentation that I need to understand how UML works. Partition: I guess if the filesystem is not a file but a partition, the host system will even not try to cache it - the whole or in part -, only the UML will use it (yes, the host system too, but like a proxy I guess). >> >>if the answers can be found somewhere, please let me know the urls >> or some very specific keywords :-) >> > >> > >> > Well there is http://user-mode-linux.sf.net >> >> I found this list on that one ;-) I read some part of it, but if UML >> does not fit to my needs, I don't want to spend hours/days on reading >> about it and testing. I am grateful for every answer. > > So basically you don't want to read documentation? I'm not sure that > even Linux is for you if you're not willing to put in some time reading > dox. UML is not something that you're going to understand in under an > hour. Yes, I want to read documentation as I wrote above, but only I UML could fit my needs. If it is sure, that it won't fit my needs, than I don't want to spend hours and days to learn and test it. And I don't even want to understand it in under an hour. About Linux: I am using it for several years in many situations - though I am not a kernel hacker and even do not want to be. I am grateful that you took time to answer my questions, because I think now that UML is not the thing I need and I did not have to spend hours on investigating about UML to get the information that you shared with this list. attila |
From: James N. <jn...@nk...> - 2002-12-06 16:04:37
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On Fri, 2002-12-06 at 08:20, Bogn=E1r Attila wrote: > - how stable is UML for production systems? Mostly stable. I've encountered two freezes in production. One was fixed in the last patch. I'm still trying to reproduce and find the root cause of the other, which has been causing the majority of my outages. For now, I'm only deploying naturally redundant services to UML. Once the "tracing myself and can't get out" bug is fixed, I'll start swinging over services that aren't so easy to make redundant. > - how many UMLs can be run in a PC server with about P4 2GHz, 500MB RAM,=20 > where the host machine has only one job: running UMLs, and the UMLs will=20 > not have high loads (can it handle about 20?) Heh.. I keep 512MB free on the host server just for filesystem cache. =20 I'm currently running 30 of them on a system running at about half that speed, though I admit that they're not doing very much. > - will the host OS cache the filesystems of the UMLs or it accesses them=20 > a more RAM economic way? (some of the UMLs could have 3-5 GB of filesyste= m) The host OS will cache the filesystems unless you enable "Always do synchronous disk IO for UBD" (CONFIG_BLK_DEV_UBD_SYNC) when you configure your kernel, or append "ubd=3Dsync" to your kernel options. > - are there any performance analysis? (for example comparing with=20 > freebsd jail) I'm not familiar with the performance analysis features of FreeBSD's jail. If you're only interested in how your server is performing over time, install "sysstat", a "sar" work-alike for Linux. That'll show you how your UML server is taking the strain of running a number of UMLs. If you're interested in where your UMLs are spending most of their time, a UML kernel _can_ be profiled. I've had no experience with this, but see http://user-mode-linux.sourceforge.net/gprof.html for details. =20 -James |
From: <at...@ne...> - 2002-12-06 17:51:21
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>>- how many UMLs can be run in a PC server with about P4 2GHz, 500MB RAM, >>where the host machine has only one job: running UMLs, and the UMLs will >>not have high loads (can it handle about 20?) > > > Heh.. I keep 512MB free on the host server just for filesystem cache. > > I'm currently running 30 of them on a system running at about half that > speed, though I admit that they're not doing very much. How much RAM do you have? Putting 1-1,5 Gb of RAM is not a real problem, just want to know what I should expect from such a system :-) > I'm not familiar with the performance analysis features of FreeBSD's > jail. If you're only interested in how your server is performing over > time, install "sysstat", a "sar" work-alike for Linux. That'll show you > how your UML server is taking the strain of running a number of UMLs. > If you're interested in where your UMLs are spending most of their time, > a UML kernel _can_ be profiled. I've had no experience with this, but > see http://user-mode-linux.sourceforge.net/gprof.html for details. thank you very much. attila |
From: Net L. <net...@li...> - 2002-12-06 17:58:30
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On Fri, 6 Dec 2002, [ISO-8859-1] Bogn=E1r Attila wrote: > > >>- how many UMLs can be run in a PC server with about P4 2GHz, 500MB RAM= , > >>where the host machine has only one job: running UMLs, and the UMLs wil= l > >>not have high loads (can it handle about 20?) > > > > > > Heh.. I keep 512MB free on the host server just for filesystem cache. > > > > I'm currently running 30 of them on a system running at about half that > > speed, though I admit that they're not doing very much. > > How much RAM do you have? Putting 1-1,5 Gb of RAM is not a real problem, > just want to know what I should expect from such a system :-) I'm running 20 simultaneous UML's on a box with 4GB of physical RAM. If i had the budget for more, i'd increase it. Make what you like of that. Each of the UML's is using 256MB of RAM. --=20 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Lonni J Friedman=09=09=09=09n...@li... Linux Step-by-step & TyGeMo=09=09 http://netllama.ipfox.com |
From: <at...@ne...> - 2002-12-06 18:31:33
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>> > I'm currently running 30 of them on a system running at about half >> that speed, though I admit that they're not doing very much. >> >> How much RAM do you have? Putting 1-1,5 Gb of RAM is not a real >> problem, just want to know what I should expect from such a system :-) > > I'm running 20 simultaneous UML's on a box with 4GB of physical RAM. If > i had the budget for more, i'd increase it. Make what you like of that. > Each of the UML's is using 256MB of RAM. Ok, thanks. In my configuration not every UML would need 256MB. attila |
From: Net L. <net...@li...> - 2002-12-06 18:38:35
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On Fri, 6 Dec 2002, [iso-8859-2] Bogn=E1r Attila wrote: > >> > I'm currently running 30 of them on a system running at about half > >> that speed, though I admit that they're not doing very much. > >> > >> How much RAM do you have? Putting 1-1,5 Gb of RAM is not a real > >> problem, just want to know what I should expect from such a system :-) > > > > I'm running 20 simultaneous UML's on a box with 4GB of physical RAM. I= f > > i had the budget for more, i'd increase it. Make what you like of that= =2E > > Each of the UML's is using 256MB of RAM. > > Ok, thanks. In my configuration not every UML would need 256MB. Well, if you've got 500MB of RAM, and want to run 20 simultaneous UMLs, that averages 25MB each. I doubt you're going to be able to do much of anything with that little memory. --=20 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Lonni J Friedman=09=09=09=09n...@li... Linux Step-by-step & TyGeMo=09=09 http://netllama.ipfox.com |
From: Cameron K. <cam...@pa...> - 2002-12-06 21:29:10
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On Fri, Dec 06, 2002 at 02:20:40PM +0100, Bogn?r Attila wrote: > Hello, > > I looked at some mail subjects in the archives, but found nothing about > my question: > > - how stable is UML for production systems? Depends which UML kernel you use. 2.5.19-5 is the last release, with the later ones being developmental. It also depends on whether you're going to use the skas mode, which is faster but more experimental, or the slower but better proven tt mode. > - how many UMLs can be run in a PC server with about P4 2GHz, 500MB RAM, > where the host machine has only one job: running UMLs, and the UMLs will > not have high loads (can it handle about 20?) Are the UMLs going to be using COW filesystems? I think you'll find if they are you're in for big big savings. > - will the host OS cache the filesystems of the UMLs or it accesses them > a more RAM economic way? (some of the UMLs could have 3-5 GB of filesystem) You want to let the host kernel cache, that's a Good Thing. If the host needs more memory it will simply reduce the size of the filesystem cache. > - are there any performance analysis? (for example comparing with > freebsd jail) I'm about to create one for my new server. I've written some stress testing scripts, and am looking forward to getting the numbers. My environment consists of about 25 machines (15 of which are LTSP X-Terminals), which are connected to my big bad server, which is - Dual Athlon 2000+ - 1.5GB RAM (If I need more I have to use more expensive RAM) - Hardware RAID5 (I haven't seem it used much yet in my testing, but I think I'll put my hosts swap on it as well. So far, I'm monitoring host activity with gkrellm. Each student will have 10 UML machines (this is stress levels), connected via a virtual network. All filesystems are COW. My load testing will involve seeing the performance with 1,2,5,10,20,30,40 users (that's about 400 UML machines with 40 users.) Each host will do one thing, such as serve DNS, SSH, WWW, or be a client to those services (do something client-esque to each server), or be a router. (the router will also run bwm, so I can see what kind of throughput I'm getting on them. Remember, this is /stress/ testing. Normally, the machines would be pretty idle, and they're only up for about 2 hours (the duration of the lab). I'll post on www.usermodelinux.org when I'm done. -- Cameron Kerr Email: cam...@pa... Website: http://nzgeeks.org/cameron/ |
From: Steve S. <sn...@fr...> - 2002-12-06 21:57:13
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On Sat, Dec 07, 2002 at 09:29:16AM +1300, Cameron Kerr wrote: > You want to let the host kernel cache, that's a Good Thing. If the host > needs more memory it will simply reduce the size of the filesystem > cache. And here I come again... I mean, it seems that SKAS is a Wonderful Thing, since free mem in the UML is also free mem on the host, unlike the POTM [ Plain Old TT Mode ;-p ] which use all the mem at once. So now, cutting the throat to pagecaching [ mostly inode caching ] means more "free" mem on the UML, and that way more free mem on the host which could happily cache thing with better hints than UMLs. ps. R-To [uml-devel] set Steve, inside mm/slab.c & friends... -- GPG public key available from http://snide.free.fr/gpg/snide-free.fr.asc Or by email to "snide at free.fr" with "send key pub" as subject Fingerprint: 91E3 C5F1 2641 4D0F EDD0 7116 D187 5929 14A8 FDA2 |
From: David C. <dav...@fu...> - 2002-12-07 15:38:43
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Bognár Attila wrote: > - how stable is UML for production systems? I'm running UMLs with uptimes of ~123 days with 2.4.18-48um. I've personally had most success with 2.4.19-13um from the current 2.4.19 patches. There are known issues with the current UML patches, but I'm avoiding anything following the skas merge for production usage (not that there is anything wrong with skas - I've not had a problem with it. My host does not have the host patch, however). usermodelinux.org runs on a 2.4.19-13um UML. However, you're going to need a very stable host. This is documented on my site below. I'm currently running 2.4.19-pre10-fairsched, with which I've managed >40days uptime before it needed to be rebooted for hardware maintaince. > - how many UMLs can be run in a PC server with about P4 2GHz, 500MB RAM, > where the host machine has only one job: running UMLs, and the UMLs will > not have high loads (can it handle about 20?) Not very many. I've got 1.5Gb of RAM in my box, and all the UMLs (using 128Mb each) use ~2.2Gb of /tmp space, so 700Mb is being swapped in and out on demand. I've not noticed this causing the system to run slowly, but many of the UMLs are not particularly loaded. > - are there any performance analysis? (for example comparing with > freebsd jail) I posted host/tt/skas2/skas3 benchmarks to this list a week or two ago. > if the answers can be found somewhere, please let me know the urls or > some very specific keywords :-) I run a UML server. http://uml.openconsultancy.com/. Bill Stearns does too. http://www.stearns.org/slartibartfast/ David -- David Coulson dav...@fu... www.futurenet.co.uk www.linuxformat.co.uk / www.pcplus.co.uk |