Messages in this thread | | | Date | Fri, 19 Oct 2007 00:16:37 +0200 | From | Rene Herman <> | Subject | Re: OOM notifications |
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On 10/19/2007 12:01 AM, Rene Herman wrote: > On 10/18/2007 11:18 PM, Rik van Riel wrote: > >> On Thu, 18 Oct 2007 23:06:52 +0200 >> Rene Herman <rene.herman@keyaccess.nl> wrote: >> >>> They don't -- that's why I asked if you need both scenario's active >>> at the same time. SIGDANGER would just be SIGPLEASEFREEALLYOUCAN with >>> the operator deciding through setting the level at which point >>> applications get it. >>> >>> Or put differently; what's the additional value of notifying an >>> application that the system is about to go balistic when you've >>> already asked it to free all it could earlier? SIGSEEDAMNITITOLDYOUSO? >> >> The first threshold - "we are about to swap" - means the application >> frees memory that it can. Eg. free()d memory that glibc has not yet >> given back to the kernel, or JVM running the garbage collector, or ... >> >> The second threshold - "we are out of memory" - means that the first >> approach has failed and the system needs to do something else. On an >> embedded system, I would expect some application to exit or maybe >> restart itself. > > That first threshold sounds fine yes. To me, the second mostly sounds > like a job for SIGTERM though. > > The OOM killer could after it selected the task for killing first try a > TERM on it to give a chance to exit gracefully and only when that > doesn't help make it eligible for killing on a second round through the > badness calculation. > > You could moreover _never_ make a task eligible for killing before it > received a SIGTERM, thereby guaranteeing that everyone got the SIGTERM > before killing anything, and it seems SIGTERM would be a more focussed > version of SIGDANGER2 then.
Well, no, that "guarantee" is fairly badly formulated but I mean "before everyone got a SIGTERM" ofcourse. That is, first do the same selection as now but don't send KILL but TERM and mark the task as having received a TERM already and make it not eligible anymore. Only when there are no TERM eligible tasks anymore, start sending KILL.
> Would at least forego any need for multiplexing the DANGER signal.
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