[Yum] Question on memory requirements

[David Timms]

Tom Mitchell wrote:
> With smaller and smaller values, try reducing the
> virtual memory limit.  Something like:
> 
>     ulimit -v 100000 ; yum -y update
>     ulimit -v  90000 ; yum -y update
>     ulimit -v  50000 ; yum -y update
>     ulimit -v  30000 ; yum -y update
> 	.... Values are in 1024-byte increments -- you can do the math.
> 
> The idea is to have the kernel return an error to malloc() requests
> larger than your physical memory limit.   This can keep yum from swapping...
> If the limit is too small it should (?) error out with grace....  I do
> not know what the lower bound is...   ;-)

Had a play with this today. I have only one outstanding update:
Updating:
   docbook-utils-pdf    noarch  0.6.14-11.fc8 updates         11 k

Started low on umlimit and incremented. Each  time python or rpm would 
have one or more of:
- memory alloc (155288 bytes) returned NULL.
- MemoryError
- /etc/selinux/targeted/contexts/files/file_contexts.local:  line 5 has
invalid regex ^/lib/libglide3-v.\.so$:  Memory exhausted

Result:
-30000 etc see error messages above.
-180000 loads my repos {fresh/updates/fedora}, detects update and began
to install, crapping out during the hashes
-182000 the hash marks finish but the terminal hung - ctrl-c, ctrl-z no
effect. {afterwards, further rpm/yum attempts hang - reboot to fix}
-182131 fails as above {memory alloc (207544 bytes) returned NULL.}
-182132 succeeds
-184000 the update succeeds

Multiplying the lowest succeed by 1024 gives: 186,503,168 bytes of 
virtual memory given to shell, so that the update can work. Seems pretty 
large {178MB}, but it fits with for eg Fedora's release note statement of:
Minimum RAM for graphical: 192MiB
Recommended RAM for graphical: 256MiB
as long as you have swap.

DaveT.