Am Sunday 08 January 2012 schrieb Thomas Goirand: > On 01/08/2012 02:43 PM, Chow Loong Jin wrote: > > On 08/01/2012 01:48, Rainer Dorsch wrote: > >> Hello, > >> > >> I recently setup zram (for compressed swap space in RAM) on an older low > >> RAM machine. I was quite happy with the result and started now to do > >> the same setup also on my other machines. I am wondering if anybody is > >> investigating, if debian should do that by default when installing a > >> new machine or even better also when machines get upgraded. > >> [...] > > > > In my experience from using a zram + on-disk swap setup, performance is > > only good until the zram swap gets filled up. Then performance goes to > > hell because you'll be functioning primarily on your on-disk swap while > > your zram swap just acts as deadweight sitting around taking up memory. > > What I usually did at that point was to swapoff the zram swap to force > > everything into the on-disk swap, rmmod, and re-create the zram swap > > again to get free zram swap space. > > > > I don't think it's a good idea to make this default. > > I and my ex-employee had similar experience. I also wouldn't recommend it.
Thank you for the feedback. I saw zram as another level of memory hierarchy with performance between (uncompressed) main memory and disk. But indeed I never saw a system going out of zram and swaping on disk. For me, zram was essentially a fast disk replacement and performed therefore (?) well. From your experiences it seems enabling zram by default needs at least more sophisticated algorithms, which decide when it is a good idea to enable zram and when not... For reference, my (desktop) system looks like blackbox:~# swapon -s Filename Type Size Used Priority /dev/sdd partition 3910652 0 -1 /dev/zram0 partition 2070080 6360 100 /dev/zram1 partition 2070080 6388 100 blackbox:~# i.e. instead of using a small fraction of disk, zram is used. Thanks, Rainer -- Rainer Dorsch http://bokomoko.de/ -- To UNSUBSCRIBE, email to debian-devel-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/201201082009.51628...@bokomoko.de