21 Nov
2011
21 Nov
'11
2:33 p.m.
Hi All,
I'm about to set up a new linux box, but not all of the bits have arrived
yet. I currently only have 512MB of RAM in the machine, but ultimately, it
will have at least 2GB, possibly 4.
If I let the installer do it's own thing with HDD partitioning, it will set
up a swap size of 2 x RAM. But that's not what I want. 2 x the current
amount of RAM will be inadequate once I install more.
So, if I set up 8GB of swap, expecting that I'll eventually have 4GB of
RAM, is having too much swap going to be a problem in the meantime?
Is there a downside to having a large amount of swap?
Leigh.
21 Nov
21 Nov
2:37 p.m.
Leigh Sharpe <leigh.sharpe(a)gmail.com> wrote:
So, if I set up 8GB of swap, expecting that I'll
eventually have 4GB of
RAM, is having too much swap going to be a problem in the meantime?
I don't think so.
Is there a downside to having a large amount of swap?
No, but of course your system will slow down substantially if you use a lot of
virtual memory and it has to rely on swap space heavily.
An alternative would be to configure swap files rather than swap partitions,
allowing you to adjust the size as you wish.
2:40 p.m.
On Mon, Nov 21, 2011 at 2:33 PM, Leigh Sharpe <leigh.sharpe(a)gmail.com>wrote;wrote:
Hi All,
I'm about to set up a new linux box, but not all of the bits have arrived
yet. I currently only have 512MB of RAM in the machine, but ultimately, it
will have at least 2GB, possibly 4.
If I let the installer do it's own thing with HDD partitioning, it will
set up a swap size of 2 x RAM. But that's not what I want. 2 x the current
amount of RAM will be inadequate once I install more.
So, if I set up 8GB of swap, expecting that I'll eventually have 4GB of
RAM, is having too much swap going to be a problem in the meantime?
Is there a downside to having a large amount of swap?
Personally I think swap = ram x 2 is an old rule that doesn't make sense
any more.
Unless you plan to suspend, then you really don't need any more than 1gb of
swap.
Just enough for the kernel to use for paging things in and out.
Quite frankly if you find yourself needing 1gb of swap, or even 500mb of
swap then you need to re-evaluate your hardware.
cheers,
/ Brett
2:45 p.m.
On 20/11/11 19:33, Leigh Sharpe wrote:
I'm about to set up a new linux box, but not all
of the bits have
arrived yet. I currently only have 512MB of RAM in the machine, but
ultimately, it will have at least 2GB, possibly 4.
er, RAM is now $10/GB. I see no reason for using anything less then 8 or 16.
Two of my three laptops have 8GB (both T410's, it's the most they'll
do), the last is my occasional mac which only has 2GB (can take 4, but
it's due for replacement). My desktops one has 12, one 24 (both are
triple channel Intel machines). My personal servers are all at 8GB as
they're older machines (except for a HP MicroServer used as a NAS which
I've yet to upgrade from 1GB).
If I let the installer do it's own thing with HDD
partitioning, it will
set up a swap size of 2 x RAM. But that's not what I want. 2 x the
current amount of RAM will be inadequate once I install more.
So, if I set up 8GB of swap, expecting that I'll eventually have 4GB of
RAM, is having too much swap going to be a problem in the meantime?
Is there a downside to having a large amount of swap?
For the last few years I've gone to using a flat 2GB of swap. My theory
is that hard drives are *so* slow (at 100MB/sec that's 20sec to fill it)
that you'd much rather services be killed by the OOM killer then wait
minutes for a response (when you're fairly likely just to need to kill
it anyway). This is for laptops, desktops and servers (and several
hundred of them at my last job were built this way).
3:31 p.m.
On Sun, 20 Nov 2011, Julien Goodwin wrote:
On 20/11/11 19:33, Leigh Sharpe wrote:
Um, mobos that can only fit 4GB?
Laptops that are new can barely take many more. Still. Stupid market
only wanting Windows 32 bit.
The upgrading treadmill that crappy developers force upon us because they
can't be bothered to write efficient programs anymore are a great cause of
the wastage that modern society suffers from. I keep buying machines that
are maxed out with memory at purchase time, but a few years down the track
are suffering with a workload that doesn't seem like it should be all that
different. Meanwhile, I can't just upgrade ram, because the mobo is
already maxed out. I have to upgrade the whole computer despite the rest
of it still working well (partly because I've been able to incrementally
improve bits of it as bits improved).
'course, the linux VMM sucks mightily. I would have upgraded to kFreeBsd
by now if I didn't want to run a proprietry web browser that isn't built
for kFreeBsd+debian. Actually, that webbrowser is the primary reason why
I run deeply into swap. But it copes better than firefox even after it
repeatedly finally allegedly solves that old memory leak problem once and
for all.
I'm about to set up a new linux box, but not
all of the bits have
arrived yet. I currently only have 512MB of RAM in the machine, but
ultimately, it will have at least 2GB, possibly 4.
er, RAM is now $10/GB. I see no reason for using anything less then 8 or 16. Two of my three laptops have 8GB (both T410's,
it's the most they'll
do), the last is my occasional mac which only has 2GB (can take 4, but
it's due for replacement). My desktops one has 12, one 24 (both are
triple channel Intel machines). My personal servers are all at 8GB as
they're older machines (except for a HP MicroServer used as a NAS which
I've yet to upgrade from 1GB).
I don't want a desktop because I want my electricity usage to be below a
constant 60watts. My 2 laptops and a small pile of external disks manages
this according to my UPS.
--
Tim Connors
3:50 p.m.
On 20/11/11 20:31, Tim Connors wrote:
I only run a desktop at work because I'm forced to, and my one at home
is for games. Haven't done proper power measurements on my servers
though, but I do everything possible to keep the power usage down, as
that keeps the heat down.
On Sun, 20 Nov 2011, Julien Goodwin wrote:
Either they're single stick mobo's for compact systems, or you should
upgrade.
On 20/11/11 19:33, Leigh Sharpe wrote:
Um, mobos that can only fit 4GB? I'm about to set up a new linux box, but not
all of the bits have
arrived yet. I currently only have 512MB of RAM in the machine, but
ultimately, it will have at least 2GB, possibly 4.
er, RAM is now $10/GB. I see no reason for using anything less then 8 or 16. Laptops that are new can barely take many more.
Still. Stupid market
only wanting Windows 32 bit.
My (now four year) old T61 could take 8GB (except it overheated, 6GB was
reliable).
The upgrading treadmill that crappy developers force
upon us because they
can't be bothered to write efficient programs anymore are a great cause of
the wastage that modern society suffers from. I keep buying machines that
are maxed out with memory at purchase time, but a few years down the track
are suffering with a workload that doesn't seem like it should be all that
different. Meanwhile, I can't just upgrade ram, because the mobo is
already maxed out. I have to upgrade the whole computer despite the rest
of it still working well (partly because I've been able to incrementally
improve bits of it as bits improved).
I will say that some of this is new algorithms that are only practical
with large amounts of RAM, some of the simulation stuff we use in Google
NetOps is like that.
'course, the linux VMM sucks mightily. I would
have upgraded to kFreeBsd
by now if I didn't want to run a proprietry web browser that isn't built
for kFreeBsd+debian. Actually, that webbrowser is the primary reason why
I run deeply into swap. But it copes better than firefox even after it
repeatedly finally allegedly solves that old memory leak problem once and
for all.
Opera doesn't do that, and as it's the only proprietry browser I'm aware
of on Linux I
Two of my
three laptops have 8GB (both T410's, it's the most they'll
do), the last is my occasional mac which only has 2GB (can take 4, but
it's due for replacement). My desktops one has 12, one 24 (both are
triple channel Intel machines). My personal servers are all at 8GB as
they're older machines (except for a HP MicroServer used as a NAS which
I've yet to upgrade from 1GB).
I don't want a desktop because I want my electricity usage to be below a
constant 60watts. My 2 laptops and a small pile of external disks manages
this according to my UPS. 
4:09 p.m.
On Mon, 21 Nov 2011, Julien Goodwin <luv-lists(a)studio442.com.au> wrote:
Either they're single stick mobo's for compact systems, or you should
upgrade.
The biggest problem that I have observed is motherboards with Intel chipsets
that can only address 4G of RAM and reserve ~700M of that for PCIe thus
leaving only ~3.3G of addressable RAM. My latest system has 4 DIMM slots and
only 3.3G usable.
A large part of my motivation for moving to a desktop was to avoid the heat
problems in my Thinkpad which had 5G and could have been expanded to 8G. 3.3G
is enouugh as I use a Xen server on my network (compared to KVM on localhost
when using the Thinkpad) and I avoid having too many Chromium tabs open at
once.
Sure, but then there's the fact that web browsing worked quite nicely on a
system with 16M of RAM in 1995 and a significant part of my web browsing
hasn't changed much since then.
One thing to note is that you have to measure these things. There is overlap
between laptop and desktop power use. You can get a 64bit desktop system
running on about 60W including monitor while the high-end laptops apparently
exceed 100W - I've heard accounts of airlines providing only 120W of
electricity to a passenger and having the circuit-breaker trip when a laptop
is plugged in.
--
My Main Blog http://etbe.coker.com.au/
My Documents Blog http://doc.coker.com.au/
er, RAM is now $10/GB. I see no reason for using
anything less then 8 or
16.
Um, mobos that can only fit 4GB? Laptops that
are new can barely take many more. Still. Stupid market
only wanting Windows 32 bit.
My (now four year) old T61 could take 8GB (except it overheated, 6GB was
reliable). The upgrading
treadmill that crappy developers force upon us because they
can't be bothered to write efficient programs anymore are a great cause
of the wastage that modern society suffers from. I keep buying machines
that are maxed out with memory at purchase time, but a few years down
the track are suffering with a workload that doesn't seem like it should
be all that different. Meanwhile, I can't just upgrade ram, because the
mobo is already maxed out. I have to upgrade the whole computer despite
the rest of it still working well (partly because I've been able to
incrementally improve bits of it as bits improved).
I will say that some of this is new algorithms that are only practical
with large amounts of RAM, some of the simulation stuff we use in Google
NetOps is like that. I don't
want a desktop because I want my electricity usage to be below a
constant 60watts. My 2 laptops and a small pile of external disks
manages this according to my UPS.
I only run a desktop at work because I'm forced to, and my one at home
is for games. Haven't done proper power measurements on my servers
though, but I do everything possible to keep the power usage down, as
that keeps the heat down.
23 Nov
23 Nov
10:23 a.m.
On Mon, Nov 21, 2011 at 4:09 PM, Russell Coker <russell(a)coker.com.au> wrote:
On Mon, 21 Nov 2011, Julien Goodwin
<luv-lists(a)studio442.com.au> wrote:
Really?
I can't speak for how you browse the web today, or in 1995, but my habits
are vastly changed.
There were no tabbed browsers back then, so I remember a very serialised
process of loading a page, reading it, and then following a link.
Doing one thing at a time.
There was no webmail, so I didn't have gmail open, that was done via telnet
and pine.
There were no twitter, facebook, youtube, google music, web forums, wikis,
and the like. Those use a lot of ram.
Now, I have, on this computer, 4 Chromium windows open, each one with
between 5 and 15 tabs open.
I switch between tabs as I need, and open many tabs in the background then
process them, rather than doing things in a serial way.
This has a cost in memory, clearly, but that's why I have machines with 8gb
of ram in them.
I think if you're honest with yourself you'll admit that the way you
browsed the web in 1995 has absolutely no similarities with how you do it
now.
cheers,
/ Brett
I will say that some of this is new algorithms
that are only practical
with large amounts of RAM, some of the simulation stuff we use in Google
NetOps is like that.
Sure, but then there's the fact that web browsing worked quite nicely on a
system with 16M of RAM in 1995 and a significant part of my web browsing
hasn't changed much since then.
12:34 p.m.
Hello,
Russell Coker:
high-end laptops apparently exceed 100W - I've
heard accounts of airlines
providing only 120W of electricity to a passenger and having the circuit-
breaker trip when a laptop is plugged in.
Odds are that would be charging current, though, not power consumption.
Jiri
--
Jiri Baum <jiri(a)baum.com.au> http://www.baum.com.au/sabik
1:02 p.m.
On Wed, 23 Nov 2011, Jiri Baum <jiri(a)baum.com.au> wrote:
Russell Coker:
http://www.tomshardware.com/reviews/technical-foundations-diy-solar-powered-
pc,1693.html
If a laptop when charging uses >120W then it probably uses >60W when active
which makes it in the same range as desktop systems. Admittedly the above PC
design from Tom's Hardware is quite a bit different from what most of us have
on our desktops. But I think it demonstrates that a desktop PC designed for
low power use can equal high end laptops for power use while beating them for
performance.
--
My Main Blog http://etbe.coker.com.au/
My Documents Blog http://doc.coker.com.au/
high-end laptops apparently exceed 100W -
I've heard accounts of airlines
providing only 120W of electricity to a passenger and having the circuit-
breaker trip when a laptop is plugged in.
Odds are that would be charging current, though, not power consumption.
4:14 p.m.
On Mon, 21 Nov 2011, Julien Goodwin <luv-lists(a)studio442.com.au> wrote:
http://etbe.coker.com.au/2007/09/28/swap-space/
The above URL is for the most popular blog post I have ever written. In it I
describe the reasons for the 2*RAM rule and why it doesn't apply nowadays. I
also speculated about whether I would ever use more than 2G of swap, since
then I have found cases where large amounts of swap are useful. The case for
2+G of swap is when you have lots of browser tabs open at once and not doing
anything. For a desktop system I have found no other usage case where such
large amounts of swap do any good. For a server I have NEVER found a case
where large amounts of swap were ever any good, but I concede the fact that
there are surely some daemons out there which allocate large amounts of RAM
and do little with it.
--
My Main Blog http://etbe.coker.com.au/
My Documents Blog http://doc.coker.com.au/
If I let the
installer do it's own thing with HDD partitioning, it will
set up a swap size of 2 x RAM. But that's not what I want. 2 x the
current amount of RAM will be inadequate once I install more.
So, if I set up 8GB of swap, expecting that I'll eventually have 4GB of
RAM, is having too much swap going to be a problem in the meantime?
Is there a downside to having a large amount of swap?
For the last few years I've gone to using a flat 2GB of swap. My theory
is that hard drives are *so* slow (at 100MB/sec that's 20sec to fill it)
that you'd much rather services be killed by the OOM killer then wait
minutes for a response (when you're fairly likely just to need to kill
it anyway). This is for laptops, desktops and servers (and several
hundred of them at my last job were built this way). 
8:54 p.m.
Leigh Sharpe wrote:
Hi All,
I'm about to set up a new linux box, but not all of the bits have arrived
yet. I currently only have 512MB of RAM in the machine, but ultimately, it
will have at least 2GB, possibly 4.
If I let the installer do it's own thing with HDD partitioning, it will set
up a swap size of 2 x RAM. But that's not what I want. 2 x the current
amount of RAM will be inadequate once I install more.
AIUI "twice the RAM" is advice for pre-Linux unices that did something
particularly dumb -- maybe stop-and-copy paging or something.
IMO, the Right Thing is to
1. no swap. If you need 2GB of memory, buy 2GB of RAM;
2. no RAM overcommit. This means malloc returns an error rather
than handing the problem over to the OOM killer.
3. fix any programs that make inappropriately large, up-front
mallocs; likewise those that do not handle errors from malloc
appropriately (even if "appropriately" means asserting malloc
success).
Obviously this advice is inappropriate in some contexts - varnish
obviously springs to mind.
9:14 p.m.
On Mon, 21 Nov 2011, "Trent W. Buck" <trentbuck(a)gmail.com> wrote:
AIUI "twice the RAM" is advice for pre-Linux
unices that did something
particularly dumb -- maybe stop-and-copy paging or something.
It's for Unix systems that allocated a page in swap for every page in virtual
memory.
IMO, the Right Thing is to
1. no swap. If you need 2GB of memory, buy 2GB of RAM;
That's almost never the best advice. There are always pages that never get
accessed after initialisation and can be paged out.
I even use swap on my EeePC 701...
2. no RAM overcommit. This means malloc returns an
error rather
than handing the problem over to the OOM killer.
Given that RAM is cheap and disk space is usually plentiful that's a viable
option nowadays. Of course you will probably encounter programs that malloc()
vastly more memory than they need which happen to work well on the majority of
Linux systems.
3. fix any programs that make inappropriately large,
up-front
mallocs; likewise those that do not handle errors from malloc
appropriately (even if "appropriately" means asserting malloc
success).
Obviously this advice is inappropriate in some contexts - varnish
obviously springs to mind.
Also most people on this list aren't capable of following step 3. Even I
would be hesitant to do that, I already have enough bugs to fix.
--
My Main Blog http://etbe.coker.com.au/
My Documents Blog http://doc.coker.com.au/
22 Nov
22 Nov
10:04 a.m.
On 21/11/11 20:54, Trent W. Buck wrote:
1. no swap. If you need 2GB of memory, buy 2GB of
RAM;
There's a relatively recent article (Feb 2011) in Linux Journal
about swap and Linux here:
http://www.linuxjournal.com/article/10678
cheers,
Chris
--
Chris Samuel : http://www.csamuel.org/ : Melbourne, VIC
10:25 a.m.
At 10:04 AM 11/22/2011, Chris Samuel wrote:
On 21/11/11 20:54, Trent W. Buck wrote:
Quite an informative article.
73 de VK3JED / VK3IRL
http://vkradio.com
1. no swap. If you need 2GB of memory, buy 2GB
of RAM;
There's a relatively recent article (Feb 2011) in Linux Journal
about swap and Linux here:
http://www.linuxjournal.com/article/10678
4146
days inactive
4148
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15 comments
10 participants
participants (10)
-
Brett Pemberton -
Chris Samuel -
Jason White -
Jiri Baum -
Julien Goodwin -
Leigh Sharpe -
Russell Coker -
Tim Connors -
Tony Langdon -
Trent W. Buck