Messages in this thread | | | Date | Tue, 28 Mar 2000 16:02:38 +0200 (CEST) | From | Marco Colombo <> | Subject | Re: Avoiding OOM on overcommit...? |
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On Tue, 28 Mar 2000, Jesse Pollard wrote:
> --------- Received message begins Here --------- > Marco Colombo <marco@esi.it> > > On Mon, 27 Mar 2000, Linda Walsh wrote: > > > > > Khimenko Victor wrote: > > > > There is small difference: there are disk quotas, but there are NO memory > > > > quotas :-( Per-user ones, not per-process ones I mean... > > > --- > > > Maybe there need to be memory quotas. Dunno. But referring to the > > > file system. It is the file doing the write that returns with an error > > > code. Not another random process that happened to be using disk space. Also, > > > reserving 5% (for root) isn't considered to be a horrible kludge to allow > > > for recovery from such situations. > > > > But 5% reservation is not there for recovery from FS full situation. > > Ext2 guys should drop a word here, but AFAIK it's mainly for performance > > reasons (it was for FFS, where it was introduced the first time: at 95% > > many allocation optimizations simpy failed). > > It was also made available to root to use so that syslog could continue > to write to the root file system. Also, I believe pipe buffers were optionally > stored in the root filesystem under tight memory conditions. Filling root > with user data usually caused the system to hang trying to handle pipes and > domain sockets (which syslog used...). > > The reserve then allowed the root user time to log in and clean up some > things before the system died. Most user processes were put to sleep.
Just an useful side effect. 5% reserve was introduced for performance reasons, i believe.
The root FS can be filled with *root* data, too. That's why syslogd writes to /var/log. 5% reserve is not a great idea to avoid FS full. It helps sometimes. No user processes should be allowed to write on the root FS, anyway (yes, I hate /tmp, and /var/tmp, too).
> At least this was the case under UNIX System V release 2. > > ------------------------------------------------------------------------- > Jesse I Pollard, II > Email: pollard@navo.hpc.mil > > Any opinions expressed are solely my own. >
.TM. -- ____/ ____/ / / / / Marco Colombo ___/ ___ / / Technical Manager / / / ESI s.r.l. _____/ _____/ _/ Colombo@ESI.it
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