Thread: RE: Expectations of MEM requirements for a DB with

RE: Expectations of MEM requirements for a DB with

From
"Robert D. Nelson"
Date:
>Thats very true.  FreeBSD is a little smarter, and actualy kills a runaway
>process if it allocates more memory than is available.  It of course tries

It's less about its ability to kill processes (Linux does it too), but sane
default timeouts. I dunno about FreeBSD, but it can take Linux over an hour
to report an out of memory condition in any definitive form - the box
slowing to a crawl doesn't count as definitive ;) It's kinda like, why do I
have to wait 2 minutes for telnet to kill itself if I telnet to a bad
address in windows?

>to
>page things in and out of swap first, hoping the high memory condition will
>soon resolve its self.  FreeBSD is also one of the only OSes I've seen that
>kick processes (idle ones, i.e., cron, getty, etc) out of memory for kernel
>buffers and disk cache to improve preformance for busier ones.

Well that's kinda dangerous in and of itself. I haven't run into *too many*
OOM conditions (I do try and stack my boxes! er...) but I've noticed linux
tends to kill kswapd first :/


Rob Nelson
rdnelson@co.centre.pa.us


Re: Expectations of MEM requirements for a DB with

From
Bruce Guenter
Date:
On Tue, Nov 07, 2000 at 08:25:00AM -0500, Robert D. Nelson wrote:
>  I haven't run into *too many*
> OOM conditions (I do try and stack my boxes! er...) but I've noticed linux
> tends to kill kswapd first :/

Linux (at least in the discussions I've heard on the kernel mailing
list) is very careful to select non-critical user processes to kill, and
I would be extremely surprised if it picked one of its own threads
(kswapd is a kernel thread).  I've never seen it happen, but I've only
had a few OOM situations myself.
--
Bruce Guenter <bruceg@em.ca>                       http://em.ca/~bruceg/

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