[ale] Anyone know if this is true?
Rich Faulkner
rfaulkner at 34thprs.org
Thu Oct 13 13:14:32 EDT 2011
Noob to Hawk in one easy lesson. Jump in the pool...down the rabbit
hole with you!
On Thu, 2011-10-13 at 13:07 -0400, Ron Frazier wrote:
> Ahh, very clever. Hook me in with my own idea. 8-) I would consider
> it. I'd also have to consider if I can allocate the 20+ hours it
> would probably take to get ready. My findings are currently very very
> preliminary. Also, I'm one of the more newbie Linux users in the
> group. I'm not sure how qualified I am. What did you have in mind?
>
> Ron
>
> On 10/13/2011 11:51 AM, Jim Kinney wrote:
>
> > So can you consider a presentation of your findinds and perhaps some
> > testing?
> > :-)
> >
> >
> > On Oct 13, 2011 10:52 AM, "Ron Frazier"
> > <atllinuxenthinfo at c3energy.com> wrote:
> >
> > Hi guys,
> >
> > This thread has prompted me to do a bit of research to try
> > to see if I can find a consensus on the swap size issue. At
> > the moment, it seems like ask 100 people and get 100
> > different opinions. I haven't uncovered enough data to
> > tabulate and summarize it at this point. I'm pretty sure my
> > linux machines have plenty of swap for applications. I have
> > 8 GB of swap on two machines which have 8 GB of RAM. If I
> > look at the system monitor program in Gnome, it looks like
> > the swap is rarely ever touched. By the way, having 8 GB of
> > RAM in a laptop is a nice, new, liberating experience for
> > me. It's really nice to be able to open several dozen
> > browser tabs and a dozen or more applications without the
> > machine even breathing too hard. This is my first laptop
> > capable of that. I also have 8 GB of swap on a machine with
> > 4 GB of RAM, so it should be sitting pretty, so to speak. I
> > haven't found anything that says extra swap is harmful.
> > What I don't know, is whether the two 8 GB machines would be
> > able to hibernate (suspend to disk) properly, if the swap is
> > equal to the RAM. I may have to increase the swap on those
> > to 10 GB - 12 GB. This is not an issue in Windows since it
> > uses a separate hibernate file.
> >
> > In my research, I found this article
> > ( http://lukasz.szmit.eu/2009/11/compcache-swap-on-linux-desktop.html ). The article is a bit old, but this talks about a fascinating project called Compcache. Here's a quote from the page:
> >
> > ---> quote on <---
> >
> > Compcache is an open source project implementing an
> > innovative approach to swap. This has been done before, but
> > not for swap. Users of DOS and early Windows versions will
> > remember DoubleSpace/DriveSpace, which was used to virtually
> > expand available disk space, by storing files in a
> > compressed form. Compcache does exactly that, but for swap,
> > by creating a new block device in the system which
> > interfaces with the special compressed memory region in RAM.
> > On the plus side, Compcache can also be configured to use an
> > alternative swap device when the RAM swap area is full.
> >
> > ---> quote off <---
> >
> > I think that is a really cool idea for low resource
> > machines. While I don't know if I'll ever use it, since my
> > modern machines have a decent amount of RAM, it could really
> > benefit older, smaller machines. For example, I have an old
> > IBM Thinkpad with 160 MB (yes MB) of RAM. I've pretty much
> > retired the machine. It does run a GUI based version of
> > Linux, just barely, but is painfully slow. The old 300 MHz
> > processor doesn't help much either. I think I have an old
> > version of Lubuntu on it. Anyway, this type of technology
> > could give the machine more breathing room by compressing
> > the memory, so it would be like having 256 MB of RAM. I
> > also have an old Toshiba laptop which is topped out at 1 GB
> > or RAM. Both Ubuntu 10.04 and Windows XP run pretty well.
> > However, I could compress 512 MB of RAM and then effectively
> > have 512 MB or normal RAM and 1 GB of swap.
> >
> > Here's the link for the Compcache project:
> > http://code.google.com/p/compcache/
> >
> > Here's an interesting quote from their site: "With compcache
> > at hypervisor level, we can compress any part of guest
> > memory transparently."
> >
> > Now, while I'll admit I don't understand all the
> > implications of that statement, it looks like you could
> > essentially compress all the RAM if running a lightweight
> > hypervisor and running your OS as a guest.
> >
> > The project website also points out that embedded systems
> > could benefit from the technology, where you have to justify
> > every chip you put into a device.
> >
> > Finally, here is an interesting quote from the original
> > article:
> >
> > ---> quote on <---
> >
> > On my desktop, a Dell Precision S390 with 2GB DDR2 RAM and a
> > Maxtor Diamond Max 9 80GB drive, I am getting the following
> > hdparm results (average of three runs) for my disk swap, and
> > my compcache swap:
> > * Swap on disk: 58MB/s
> > * Compcache swap: 557MB/s
> > An order of magnitude better bandwidth at no expense? I like
> > that.
> >
> > ---> quote off <---
> >
> > I like that idea too. I'd like to know what you guys think
> > of this concept.
> >
> > Sincerely,
> >
> > Ron
> >
> > On 10/13/2011 8:58 AM, Rich Faulkner wrote:
> >
> > > For me depends upon the system as to swap size, but if I
> > > plan on using hibernation features I have swap just over
> > > the size of RAM as in 1-1/2 times as the general (old)
> > > rule that I've followed...generally a couple of gigs for a
> > > desktop and I leave it at that. Being as I'm only
> > > building desktops and laptops lately I'm not speaking to
> > > servers. An interesting experiment is to do test installs
> > > to various system configs and see what a given distro will
> > > do for a default installation. I consider this a
> > > benchmark from the developers on an "ideal" configuration
> > > given the hardware provided. RinL
> > >
> > >
> > > On Thu, 2011-10-13 at 08:45 -0400, Scott Castaline wrote:
> > >
> > > > On 10/12/2011 09:40 PM, Tavarvess Ware wrote:
> > > > >
> > > > > Scott I read the ram x 2= swap in my Linux classes as well and have
> > > > > generally followed that, but with memory soaring as it has lately i am
> > > > > starting to rethink that. A system 48gigs of memory would be 96 in
> > > > > swap..... I wonder if te old format has changed and I haven't heard yet.
> > > > >
> > > > I only go RAM x 2 = swap for the 1st 2 GB of RAM so 2GB RAM = 4GB swap.
> > > > From there on it's RAM x 1 = swap so 4GB RAM = 6GB swap. So your 48 GB
> > > > of RAM = 50GB swap, and yup that's one hell of a lot of swap space.
> > > > >
> > > > > On Oct 12, 2011 9:32 PM, "Scott Castaline" <skotchman at gmail.com
> > > > > <mailto:skotchman at gmail.com>> wrote:
> > > > >
> > > > > On 10/12/2011 04:14 PM, planas wrote:
> > > > > > On Wed, 2011-10-12 at 15:13 -0400, Geoffrey Myers wrote:
> > > > > >> 'Just so you all know, when determining how much space to assign to
> > > > > >> swap: Swap isn't just used for paging or virtual memory
> > > > > management; swap
> > > > > >> is also used by power management for suspend-to-disk
> > > > > (hibernation). '
> > > > > >>
> > > > > >> I seriously don't know, so I'm asking.
> > > > > >>
> > > > > >
> > > > > > I have seen that a good swap size is ~1.5x the RAM.
> > > > > > --
> > > > > > Jay Lozier
> > > > > > jslozier at gmail.com <mailto:jslozier at gmail.com>
> > > > > >
> > > > > >
> > > > > >
> > > > > I remember from somewhere that upto 2GB use 2.0x RAM above 2GB of
> > > > > RAM go
> > > > > with 1:1 ratio so 4Gb RAM = 6GB swap. I don't remember why 2x on the
> > > > > first 2GB and this goes back to when 4GB was a lot on pre-configured
> > > > > retail boxes. So like Geoffrey I can't see having 18GB of swap for a
> > > > > 16GB machine.
> > > > >
>
>
>
> --
>
> (PS - If you email me and don't get a quick response, you might want to
> call on the phone. I get about 300 emails per day from alternate energy
> mailing lists and such. I don't always see new messages very quickly.)
>
> Ron Frazier
>
> 770-205-9422 (O) Leave a message.
> linuxdude AT c3energy.com
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