Messages in this thread |  | | | Date | Tue, 18 Nov 1997 19:56:49 +0100 | | From | Steffen Ullrich <> | | Subject | Re: Ideas for memory management hackers. ( "importance levels" ) |
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Because nobody except one made a comment to this I post it again (this time with the right Subject line). If still nobody replies - forget about it (although I really would like to know why this should be a bad or useless idea )
On Fri, Nov 14, 1997 at 07:37:25PM +0100, Steffen Ullrich wrote: > Rik van Riel wrote: > > > > Send Linux memory-management wishes to me: I'm currently looking > > for something to hack... > > what I really like to see is something like various "importance levels" for > processes. imagine the following: An remote system behaves really bad and you > want to have a look at it. You try to telnet to the machine but what happens > there is that inetd tries to spwan in.telnetd. Because the system is already > heavily used it cant get the memory/swap space needed to start in.telnetd on > this system. A nice thing in this case would be that the system could be > configured to consider in.telnetd as a very important application and do > everything to start it, even if it needs to kill some less important processes. > > I had similar problems several times on OSF/1 (DEC UNIX) where I run a big > application on a remote machine. I guess the following happened: > The application took more and more memory but now another process got scheduled > by the system so the system needed to move some pages of my app to the swap > space. unfortunatly there wasn't any more space so OSF/1 too his strategy to get > some free space - it killed the processes which were not used for the longest > time. unfortunatly in this cases this was inetd :( > > It was probably a bit different but that is what I understood from the > explanation I got. There are two modes of allocating swap space in OSF/1. > one is the deferred mode which allocates a page in the swap space once a page > needs to be swapped out, the other more conservative mode allocates a space > in the swap area for each page used by the system. The first mode is a bit > faster and uses less memory but has the problem above. The machine used the > deferred mode which is I think similar to the mode linux uses - otherwise you > couldn't run a system w/o swap space setup. > > Anyways, this kind of "importance" could be really useful because in critical > situations there would be a better chance that your important applications will > continue to run ore are able to start. > The thing I could imagine the whole issue is that every process has an > importance. If a new process gets spawned it inherits the importance if its > parent, where the mother of all processes (usually "init") gets the highest > importance on start. Then there should be a way for a process to change its > importance ( maybe a syscall similar to "nice" ). Only root process are allowed > to increase its level but everybody can decrease it. > > How does it sound or is there another/better way to deal with the above problem?
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