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SubjectRe: Virtual memory exhausted?
>>>>> "Joel" == Joel Young <jdyoung@erinet.com> writes:

Joel> I tried this the other day (I have 96Mb) and also ran out of
Joel> virtual memory (96Mb + 36Mb swap). Maybe we need newer
Joel> versions of make? I can put a number in like make -j 10 and
Joel> that works fine.

Joel> Joel jdyoung@erinet.com

Joel> On 11 Jun 1996, Simon Josefsson wrote:

>> When I try to compile the kernel with "make -j zImage" it just
>> stops with an "Virtual memory exhausted" at ~60 % done, I
>> thought that was due to all the swapping so I upgraded to 64MB
>> (had 32MB before) and I still can't do it.
>>
>> It doesn't access the disc much so the swap couldn't be =that=
>> exhausted. Any clues to get this to work?
>>
>> How much memory are you running on, when compiling
>> (successfully) with -j?
>>
>> Running linux2, 64MB, P133, AHA2940, /usr/src is IBM 1GB. I
>> still only have 256kb of cache (I'm shopping for more) so it
>> isn't much faster than with 32MB but I think that wouldn't
>> affect the virtual-memory-thing.

Here's my make:

andrewes:/Z$ make --version
GNU Make version 3.74, by Richard Stallman and Roland McGrath.
Copyright (C) 1988, 89, 90, 91, 92, 93, 94, 95 Free Software Foundation, Inc.
(yada yada yada)

I noticed that make -j can lead to trouble while compiling the
kernel. The -j options will spawn as many processes as there are
targets, and some of the kernel sections (net) have quite a few
targets (> 40?). I have found that the best make settings for me are -j5 -l5,
which won't spawn any more than 5 processes, and won't spawn more than
one process if the load average is above 5. I put these arguments into
the main Makefile (I change the value of $MAKE), since they won't get
propagated to the sub-makes otherwise. (I.e., command line aruments to
make only take effect in the top level directory.)

I have also noticed, however that make will sometimes "get loose"
from those restrictions, and spawn processes for the rest of the
targets. This happens when the load average falls below the -l limit,
after being above it, and throttled. It seems make forgets about the
-j setting at that point. I haven't reproduced this with make 3.74 for
certain, yet, but previous versions of make did this to me all the time.

BTW: I have 32MB memory, and another 73MB in two swap partitons. If I
do a plain make -j, I will run out of that. The end comes when "free"
shows that swap has run out. My load average at that time is over 15,
the machine is almost completely unresponsive, and the disk is
thrashing.

Also, unless you have an extremely fast processor (mine is 486/66),
then having more swap than I do and doing a make -j won't get it
done any faster. As I noted above, once you get a large number of
processes running, the machine stops making progress. It spends most
of its time doing housekeeping. I would be willing to bet that the
kernel source and the compiler executable have reached such a size
that a make -j on a 64MB 486/66 will also freeze. I'm not sure though.

Lately, rather than edit the Makefile and later have a patch fail, I
just live with single target makes. I read mail and browse the Web
while the kernel compiles.

"Oh Linus, your source code is so large, and my CPU is so small."

---
Andrew C. Esh mailto:andrew_esh@cnt.com
Computer Network Technology andrewes@mtn.org (finger for PGP key)
6500 Wedgwood Road 612.550.8000 (main)
Maple Grove MN 55311 612.550.8229 (direct)
http://www.cnt.com - CNT Inc. Home Page
http://www.mtn.org/~andrewes - ACE Home Page


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