Subject: Re: Memory usage (compiling)
To: Arto Huusko <email@example.com>
From: Timo Schoeler <firstname.lastname@example.org>
Date: 06/21/2005 09:26:03
thus Arto Huusko spake:
> 20.6.2005 kello 20:00, Timo Schoeler kirjoitti:
>>> so I've reinstated my
>>> ultra5 with a fresh install of the latest build snapshot (HEAD).
>>> I'm just compiling a few utilities (wget, screen etc) from pkgsrc with
>>> no other processes (and no X) running and:
>>> Memory: 52M Act, 27M Inact, 456K Wired, 5744K Exec, 58M File, 1584K Free
>>> Swap: 128M Total, 3328K Used, 125M Free
>>> Seems like the compiler is using a lot of memory! I don't know what
>>> "File" means, but the fact that the swap gets used seems like it's run
>>> out of physical memory to me.
> File means cached file data. When a file is loaded from disk, it is cached
> in memory, and when it is next accessed, all the data comes from memory
> and disk is not accessed. Unless your system really is swapping (but doing
> work otherwise), it is a good thing that you have no free memory: it
> shows the OS is using it efficiently.
>> IIRC one of my Suns (an U10 with 384MByte) started swapping building a
>> release only slightly. so ~400MByte maybe kind of a boundary, to swap or
>> not to swap. just a thought.
> I've got mozilla-gtk2 building on u5 with 320mb of ram just now. I've
> actually 75 megs free mem (but it jumps back and forth depending on
> what file is being compiled) and swap is unused. And I've X, XFCE,
> and stuff running at the same time.
> Of course things might be different if I started to actually do something
> else than just let it compile..
the machine doesn't run X or stuff, just acts as a web and mail server.
maybe building release is more work thank mozilla (altho the latter one
isn't lightweight either ;)?
>> as soon as a machine has to swap it's performance decreases awfully.
>> best is to make sure the machine has enough RAM (which, of course,
>> depends on the things the machine should do).
> Having some amount of swap used does not mean the machine is swapping.
> It could have just paged out some anon memory that is not in use. If
> I look at top output of my otherwise totally idle alpha that's been
> up for weeks, there's something like 10-20 megs of swap used. The OS
> has just decided at some point that it needs to swap out something,
> and there's been no need to swap anything back (think idle gettys
> and stuff like that).
i agree. but i meant the scenario where a machine has (very) little RAM
and does nearly everything swapping. that's a bad deal.