Messages in this thread | | | Date | Tue, 21 Jul 1998 01:25:54 +0200 | From | Marc Lehmann <> | Subject | Re: Linux behaviour in low memory situations. |
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On Sun, Jul 19, 1998 at 08:30:56PM +0000, Linus Torvalds wrote: > In article <19980719213937.08230@cerebro.laendle>, > >All the newer kernels, though, just _stop_ (not even sysrq works) without an > >oops, when there is no memory left (all 2.1.10x for example). Increasing > >sys/vm/freepages does not help at all.. > > Please tell me more about what you're doing.. I certainly see different
my machine is a 192MB dual-P-II. I either use no swap, or a dedictaed 64MB swap partition. The behaviour in low-memory situations (this is, I really stress the machine with some netscapesis (roughly) as follows:
aprx. kernel version with swap no swap 2.1.9x swap heavy for a while, immediately kill a process then just seems to stop 2.1.10x swap heavy for a while, just stop. then just seems to stop
I can reproduce this exactly by simply recompiling a (very large) c++ file (for which the compiler needs around 200MB VM).
with swap enabled, linux sometimes survives after really heavy swapping, but not when I start netscape in parallel.
In the cases where swap is enabled, the computer does not seem to really stop, it just pauses with disk activity for extended periods (minutes), and I do never wait for longer than half an hour (this is the fsck vs. swap tradeoff ;)
I got the idea of turning off swap when I found out that immediatelly killing some process was more effective than swapping for ten minutes, then stopping, then rebotting and fsck'ing.
Just for fun, I ran this test again from the console (without swap), and the computer (almost) locked up, the console didn't react to pressing return, but numlock worked. After pressing SysRq-S, I got:
SysRq: Emergency Sync
and the machine did NOT sync any drives and locked up hard (not even numlock or SysRq-B worked).
Also, 2.1.109 (only) performance is very bad once memory has been used by the buffer cache (I mean, free memory is around 9M), as if reclaiming buffers took much time.
Also, a simple find /var/spool/news (on at least 2.1.108 & 109) gives me a real 386 feeling. The window manager isn't able to redraw windows within a second, the mouse cursor motion is very sluggish (the x server runs as a realtime process), and this is on a _dual_ P-II system.
So, in general, 2.1.10x is very fast (compared to 2.0), when in good condition, but as soon as memory gets even remotely tight (or I start find), it gets almost unusable.
The 2.1.9x kernels were _much_ more usable for me.
-----==- | ----==-- _ | ---==---(_)__ __ ____ __ Marc Lehmann +-- --==---/ / _ \/ // /\ \/ / pcg@goof.com |e| -=====/_/_//_/\_,_/ /_/\_\ --+ The choice of a GNU generation | |
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