On Tue, Jan 12, 2021 at 4:06 AM Chris Murphy <lists@xxxxxxxxxxxxxxxxx> wrote: > > On Mon, Jan 11, 2021 at 1:55 PM ElXreno <elxreno@xxxxxxxxx> wrote: > > > I think it's a bad idea. It is better to make `zram-fraction` equal to > > 0.8 or 0.9, but not 1.0. > > Just to clarify. zram-fraction 1.0 means the zram *device size* will > be equal to RAM, capped at 8G. The actual amount of memory used is > zero, until the kernel starts to evict dirty pages to swap, where they > are then compressed. And the maximum amount of RAM due to compression > would be predicated on compression ratio. If we assume a conservative > 2:1 ratio (compression results in 50% of original size), the max ram > would be the lesser of 4G or 50% of RAM. For reference this is the config we ran on Fedora arm with the zram package for a number of releases before F-33 and the new tool tool over and we had few reports of issues with this factor even with devices with a small amount of real memeory so I have no concerns, in fact it just gets us back to what we had there by default in F-32. > Does this reduce your concern? > > 80% might still be reasonable, and still pretty conservative. > > > For example, if you run Darktable, load a floating-point TIFF image into > > it, and try to export it, on systems with little RAM, it will fill both > > RAM itself and zram, and cause the system to freeze completely because > > the memory is almost incompressible. > > Also, other data (video editors, for example) which are not compressible > > can get into RAM. > > Are you sure that this data is compressed in memory as well as the > on-disk encoding? The editing operations themselves surely operate on > uncompressed data, and then it's compressed upon being written to > disk. > > -- > Chris Murphy > _______________________________________________ > devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx > To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx > Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ > List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines > List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx
