On Mon, Nov 14, 2005 at 10:28:38AM -0800, Nitin Gupta wrote: | Hi, | I've been working on porting the 'compressed cache' feature | (http://linuxcompressed.sourceforge.net/ - feature explained in first few lines) | to linux 2.6 kernel. | I'm wondering why this project is dead even when it showed great | performance improvement when system is under memory pressure.
While it sounds interesting from an academic point of view, I wonder how relevant this work (and any work related to paging) is when memory can be purchased for under $200 a gigabyte. This is a different perspective than Linux which is in common use on older machines and smaller machines (even embedded systems) with small memories -- Solaris typically runs on servers requiring a specified response time. Solaris users usually consider it a *failure mode* when a system starts paging since its response time becomes non-linearly poor and unpredictable! Hence, I don't think this or any paging related projects will generate a lot of interest in Solaris. | Are there any serious drawbacks to this? | Do you think it will be of any use if ported to solaris kernel? As far as I can see, this is nearly impossible to port to Solaris, which unlike Linux allows direct mapping of pages in the page cache. Keeping compressed data pages around in memory would also require having a better idea of candidate pages to pageout than we can achieve on SPARC CPUs since these CPUs do not have hardware support for ref/mod bits (making paging candidate determination very costly). ZFS is very fast (being copy- on-write it does sequential I/Os whereas swapfs does random disk access), and it supports compression. ZFS is already slated to become the new replacement to swapfs in the near future. -- Eric Lowe Solaris Kernel Development Austin, Texas Sun Microsystems. We make the net work. x64155/+1(512)401-1155 _______________________________________________ perf-discuss mailing list perf-discuss@opensolaris.org