Gentoo Archives: gentoo-user

From: Grant <emailgrant@×××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] {OT} SSD instead of RAID1?
Date: Thu, 30 Jul 2009 13:52:40
In Reply to: Re: [gentoo-user] {OT} SSD instead of RAID1? by Alan McKinnon
1 >> OK, that's right.  How can I find out if 4GB RAM (the current amount)
2 >> is enough?  From what I understand of how Linux handles memory, it
3 >> will fill it up as quickly as possible, and then free it as necessary.
4 >>  This makes it difficult to determine how much RAM is necessary from
5 >> watching top.
6 >
7 > top lies. This has been discussed here many times. All your memory tools
8 > essentially tell you how much memory an app is able to see into, and most of
9 > that memory is shared with other stuff (like libs).
10 >
11 > You can't tell how much memory an app is using in any meaningful way, you are
12 > not supposed to even look at it as it changes millions of times a second. What
13 > you are supposed to do is select an allocation algorithm that works well for
14 > you in practice and let the kernel do the heavy lifting.
15 >
16 > Yes, the kernel does grab as much memory as it can for buffers and cache, then
17 > release it on demands. All modern operating systems have done this for many
18 > years - Linux just doesn't try and hide that fact from you :-)
19 >
20 >> I read on this list that the kernel needs *some* swap, even just a
21 >> tiny amount, to function properly.  Is that true?  If so, do you think
22 >> it would be OK to put this tiny amount of swap on a cheap SSD?
23 >
24 > Not true. I have machines with zero swap and they work just fine. I am utterly
25 > unconcerned with out of memory conditions as whether you have swap or not,
26 > when virtual memory runs out, either way you have a horrible cockup that is
27 > hard to fix. Then there's the oom-killer that comes along, stomps all over
28 > everything and just makes it worse.
30 Sounds good. Will commenting the swap line out of /etc/fstab and
31 rebooting disable swap? In order to resize the root partition to
32 include the swap paritition, I'll have to boot to LiveCD right?
34 - Grant


Subject Author
Re: [gentoo-user] {OT} SSD instead of RAID1? Alex Schuster <wonko@×××××××××.org>
Re: [gentoo-user] {OT} SSD instead of RAID1? Alan McKinnon <alan.mckinnon@×××××.com>
Re: [gentoo-user] {OT} SSD instead of RAID1? Peter Humphrey <peter@××××××××××××××.org>