Re: Possible inclusion of zram-config on default install
hi, Am Samstag, den 08.12.2012, 00:03 + schrieb Dmitrijs Ledkovs: On 7 December 2012 22:32, Fabio Pedretti fabio@libero.it wrote: It would be nice if Ubuntu could include zram-config by default. This package set up compressed RAM swap space and can lower RAM requirements for running and installing Ubuntu. It should be a win for every configuration. Since kernel 3.8 the zram module is out of staging, I am using it since precise with no problem. The bug request is here: https://bugs.launchpad.net/ubuntu/+source/zram-config/+bug/381059 Where necessaries, we already ship and include zram. E.g. ubuntu nexus7 and ac100 images. What other images do you want this for? I am not convinced it makes much sense on i386/amd64. i dont think it is arch specific at all. instead of just using it on images where we know in advance that it is needed, zram-config should be in the ship seed and get installed automatically if we detect we are below a certain memory threshold (casper already kind of does something similar for the live session). adam and i are discussing that since several UDSes, i guess one of us should just go forward and implement it ;) ciao oli signature.asc Description: This is a digitally signed message part -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
R: Re: Possible inclusion of zram-config on default install
Da: dmitrij.led...@ubuntu.com On 7 December 2012 22:32, Fabio Pedretti fabio@libero.it wrote: It would be nice if Ubuntu could include zram-config by default. This package set up compressed RAM swap space and can lower RAM requirements for running and installing Ubuntu. It should be a win for every configuration. Since kernel 3.8 the zram module is out of staging, I am using it since precise with no problem. The bug request is here: https://bugs.launchpad.net/ubuntu/+source/zram-config/+bug/381059 Where necessaries, we already ship and include zram. E.g. ubuntu nexus7 and ac100 images. What other images do you want this for? I am not convinced it makes much sense on i386/amd64. 1. Traditional swap on hard drive is still used and suggested, zram is a better alternative and a complement to it, so it may for sure be useful to everyone who actually use swap on hard drive. 2. Some derivatives (Lubuntu, Xubuntu) are mainly suggested on systems with low RAM, in this case one could still use the standard Ubuntu rather than this alternatives. 3. Not everyone has many GB of RAM, this could help these users. I am succesfully using it on a iBook PowerPC G4 (768 MB RAM) under Lubuntu and also on a MacBook Pro with 2 GB RAM (its maximum RAM size) with standard Ubuntu. Also, for example, see this bug report: https://bugs.launchpad.net/ubuntu/+source/lowmem/+bug/1050595 4. Also look at the project page http://code.google.com/p/compcache/ : The usual argument I get is - memory is so cheap so why bother with compression? So I list here some of the use cases. Rest depends on your imagination :) * Netbooks: Market is now getting flooded with these lightweight laptops. These are memory constrained but have CPU enough to drive on compressed memory (e.g. Cloudbook features 1.2 GHz processor!). * Virtualization: With compcache at hypervisor level, we can compress any part of guest memory transparently - this is true for any type of Guest OS (Linux, Windows etc.). This should allow running more number of VMs for given amount of total host memory. * Embedded Devices: Memory is scarce and adding more memory increases device cost. Also, flash storage suffers from wear-leveling issues, so its useful if we can avoid using them as swap device. 5. If you followed lkml you'll see that it's co-developed by Oracle, it's not only useful for small systems, but it's also useful on modern server environments. I have a couple of Oracle server with 32 GB, tuned by Oracle's engeneers, yet they use disk swap. Also on virtualized environment saving RAM is very useful (especially on VMWare where you pay not only the hardware RAM, but also the license to use it). 6. Lastly, as already said, it doesn't hurt so even if you have many GB of RAM the worst thing that can happen is that it make no difference if you never saturate all your RAM. -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
Re: Re: Possible inclusion of zram-config on default install
On Sat, Dec 8, 2012 at 8:49 PM, Fabio Pedretti fabio@libero.it wrote: 1. Traditional swap on hard drive is still used and suggested, zram is a better alternative and a complement to it, so it may for sure be useful to everyone who actually use swap on hard drive. I am not sure that zram makes good use of a harddrive as backing swap. My personal experience has been that either 1) Zram is enough, and there is no need to use HDD as swap; or 2) Once Zram is filled, the newer and more frequently used pages get written to HDD, and the memory used by the stale pages in Zram means that the system is slower that it would be without zram; or 3) Zram is usually enough but occasionally a misbehaving process will attempt to allocate all memory. Disabling the large on disk swap means that the bad process is OOM killed before it leaves the system unusable due to swap death. As I understand smart use of harddisk as a backing store and trim support is not currently supported, as the currently focus is keeping compcache small simple and obviously correct so it can leave staging, and work will not begin on adding such features till after 3.8 [1] . After 3.8 these performance problems may be fixed, and zram may make effective use on an on disk backing store. As it stands, I use compcache by itself without any on disk swap. Clearly on disk swap would be required for hibernate though. [1] http://code.google.com/p/compcache/issues/detail?id=98 -- John C. McCabe-Dansted -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
