VM: killing process X

[Konstantinos Peletidis]

On Fri, 28 May 2004 19:01:52 +0300
Vasilis Vasaitis <vvas at hal.csd.auth.gr> wrote:

> On Fri, May 28, 2004 at 04:17:53PM +0100, Konstantinos Peletidis
> wrote:

[snip]

> > Symfwnoi. As skotwsei thn process pou zhthse perissoterh mnhmh apo
> > osh mporoume na dia8esoume. Etsi o xrhsths mporei na epileksei poia
> > apo tis hdh yparxouses processes prepei na anaxwrhsei gia ton allo
> > kosmo(px something.big) kai na ksanatreksei thn something small.
> 
>   Αυτό κάνει ο πυρήνας χωρίς τον OOM: σκοτώνει την πρώτη διεργασία που
> ζητάει περισσότερη μνήμη απ' όσο υπάρχει διαθέσιμη.

Den to nomizw. Sto arxiko post autou tou thread anefera ena url:

http://kerneltrap.org/node/view/1010

An to diavaseis, 8a ma8eis thn istoria kapoiou talaipwrou pou symfwna me
ton Marcelo Tosatti:

<QUOTE>

Martin first reported problems with "gzip -dc file | less" (280MB file).
less was getting killed. He had no swap... I asked him to add some swap
and it works now. Fine. 

The thing is that with 2.4.22 less was being killed, but with 2.4.23-pre
he gets:

>> And yes, the app was killed:
> >
> > __alloc_pages: 0-order allocation failed (gfp=0x1d2/0)
> > VM: killing process named
> > __alloc_pages: 0-order allocation failed (gfp=0x1d2/0)
> > VM: killing process gpm
> > __alloc_pages: 0-order allocation failed (gfp=0x1d2/0)
> > VM: killing process sendmail
> > __alloc_pages: 0-order allocation failed (gfp=0x1d2/0)
> > VM: killing process less

So a lot of processes which should not get killed are dying. This is
really bad. I was afraid it could happen and it did.

What now? Resurrect OOM-killer?

</QUOTE>

Sto paradeigma tou Marcelo, h less zhthse perissoterh mnhmh apo osh htan
dia8esimh alla mexri na thn perilavei o kernel xreiasthke na pesoun
hrwika kapoies alles processes.

Epomenws, xwris ton OOM o kernel skotwnei processes mexri na vrei ton
enoxo. Den skotwnei apeu8eias thn process pou zhthse pollh (280MB)
mnhmh. Toulaxiston, auto to symperasma vgainei apo to parapanw
paradeigma.

> > 
> > Me vriskeis apolytws symfwno :-)
> 
>   Αυτό προσπαθούσε να κάνει ο OOM killer σε γενικές γραμμές (προφανώς
> χωρίς συγκεκριμένα ονόματα διεργασιών), αλλά δεν τα κατάφερνε και πολύ
> καλά οπότε και αφαιρέθηκε. Έχεις λίγο πρόβλημα στο να αποφασίσεις τι
> προτιμάς ε;

Mia pou e8ikses to zhthma, exw "ligo problhma" me thn adikaiologhth
eirwnia. Den tax8hka oute yper oute enantion tou OOM killer. Den ti8etai
8ema protimhshs. Ti8etai 8ema aksiopistias. Protimw ena aksiopisto
systhma. An o kernel mporei na apofygei tetoiou eidous "atyxhmata" - me
h xwris OOM killer - egw eimai euxaristhmenos.

> > Xmmm, mhpws 8a htan kalh idea na yparxei enas daemon ston opoio na
> > dhlwnoume to poso shmantikh einai h ka8e process (px dinontas
> > va8mous se mia klimaka apo 1 ws 10) kai o daemon autos na apofasizei
> > ti na skotwsei analoga me thn peristash?
> 
>   Ναι, επίσης να ονομάσουμε τον δαίμονα kbeautycontestd. Έλεος. :-p

Gousta einai auta. Peri oreksews... :-P

> 
> > Euxaristw gia thn apanthsh.
> 
>   Υπόψιν, επειδή φαίνεται να μην αναφέρθηκε στη συζήτηση: στον 2.4.26
> υπάρχει ο OOM killer, απλά δεν είναι ενεργοποιημένος εξ ορισμού. Άμα
> θέλεις πηγαίνεις στο General Setup -> Select task to kill on out of
> memory condition και τον ενεργοποιείς. Οπότε, πειράζεις τις ρυθμίσεις
> σου, δοκιμάζεις τι κάνει με και χωρίς, κρατάς αυτό που σου αρέσει
> περισσότερο, και όλοι είναι ευτυχισμένοι.

Den to eixa proseksei auto kata th diarkeia tou configuration. Poly kalh
h ypodeiksh sou kai se euxaristw. Bebaia, to gegonos oti sto help tou
sxetikou feature o OOM killer parousiazetai, emmesws plhn safws, ws
xeiroterh apo thn eks orismou epilogh den me ka8hsyxazei :-)

Dystyxws den einai eukolo na vrw peiramatika poios mhxanismos einai
kalyteros. Gia thn istoria, xrhsimopoiwntas kernels mexri kai ton
2.4.25(pou epishs den exei OOM by default AFAIK) den eixa tetoio
provlhma. Gi'auto allwste den ekfrazw kapoia idiaiterh protimhsh. O
2.4.26 mou ekane thn ekplhksh :-(

Den kserw pws to vlepeis esy, h oi alloi xrhstes, alla egw pistevw pws
an exeis ena systhma pou trexei X kai einai idle, kai molis o crond(no X
activity) treksei ena script pou kanei update mia database, o kernel
skotwnei ton X, tote ta pragmata einai sovara. Isws na hmoun tyxeros ws
twra epeidh den mou synevh nwritera kati tetoio. Mporei na einai
synh8ismenoo to fainomeno kai ola auta isws na einai ypervoles ek
merous mou. Opoiadhpote plhroforia sxetika me th syxnothta emfanishs
tetoiou eidous provlhmatwn 8a me boh8ouse na ektimhsw kalytera thn
katastash.

Euxaristw gia thn apanthsh sou.

> -- 
> Vasilis Vasaitis
> "A man is well or woe as he thinks himself so."

-- 
Kostas