Messages in this thread | | | From | Daniel Phillips <> | Subject | Re: What version of the kernel fixes these VM issues? | Date | Fri, 24 Aug 2001 15:18:53 +0200 |
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On August 24, 2001 10:47 am, Anwar P wrote: > We have big system (8 processors, 8GB ram), running Oracle and this other > ETL tool. Oracle is up and running all the time, and the ETL tool runs > once a day. But everytime the ETL tool runs (along with Oracle), the > system seems to run out of memory, and the server comes to a crawl, often > with keyborad response in 10 to 15 minute intervals. We are currently > using the 2.4.3-6 kernel that comes with Redhat 7.1. > > We know that Oracle comsumes no more than 2GB of memory at peak usage, and > the ETL tool itself consumes less than 1GB. But the ETL tool does process > a whole bunch of text files (total about 6GB worth of), and it runs for > about 2 hours. What happens is that while they are both running, the > filesystem cache size increases progressively, and some time later, it > begins swapping. We do have 16GB (2x RAM) of swap. And when it starts to > swap, the server responds to keystrokes/commands randomly and appears dead > for 10s of minutes. We know that together our applications do not need more > than 4GB of RAM on this 8GB box, so it is the VM that is causing this > unnecessary swapping by trying to use too much memory for filesystem cache.
There is no way your system should be going into swap under these conditions - it's a bug. We have probably fixed this already.
> So the first question is, is there any way I can limit the amount of memory > used for FS cache ?
Um, no, sorry. This should not be necessary.
> And the next one is, are there any (later) versions of the kernel that are > more sane about what the maximum FS cache it should use is ?
Please try 2.4.9 and 2.4.8-ac10. If the system slows down, look in your logs and see if there are any "allocation failed" messages. Use top or do watch cat /proc/meminfo to be sure your system isn't going into swap, and please let us know what happens.
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