Hi, The following series of patches divides swsusp into two functionally independent subsystems: - the snapshot-handling part responsible for creating and populating the snapshot-related data structure which is the list of page backup entries aka pagedir, - the swap-handling part responsible for writing the snapshot data to and reading it from swap. On suspend the snapshot-handling part creates the system snapshot and makes the data stored in the snapshot available to the swap-handling part via an interface function allowing it to transfer the data as a series of consecutive data pages, in a specific order. The swap-handling part writes the data pages to a swap partition is such a way that they can be read in exactly the same order in which they have been saved. On resume the snapshot-handling part is invoked by the swap-handling part to create the pagedir. Then, the swap-handling part is allowed to send it, with the help of an interface function, data pages that are used to populate the snapshot data structure. It is assumed that the data pages will be sent in the same order in which they have been received by the swap-handling part on suspend. Finally, the system state (from before suspend) is restored by the snaphot-handling part from the data structure handled by it. >From the point of view of the swap-handling part, the contents of the data pages provided by the snapshot-handling do not matter at all. It handles each data page in the same way without analyzing its contents and the snapshot-handling part is responsible for recognizing the metadata and using them as appropriate. Consequently, in principle the swap-handling part can be replaced with a user-space process and the interface functions used in transferring data between the two parts of swsusp can be replaced with a relatively simple kernel-user interface in the future. The approach used in this series of patches has some additional benefits: 1) the size of the pagedir is reduced by 1/4 which causes some more memory to be available on resume, 2) the amount of metadata written to swap is reduced by 3/4, 3) the artificial limitation on the pagedir size, imposed by the size of the swsusp_info structure, is lifted, 4) the size of swsusp_info structure is reduced so it can be merged with the swsusp_header structure in the future, 5) the swap-handling part does not use any global variables related to the snapshot data structure, 6) the __nosavedata variables are almost eliminated (on x86-64 the last of them is the in_suspend variable). I have divided the changes into some more or less logical steps for clarity. Although the code has been designed as proof-of-concept, it is functional and has been tested on x86-64, except for the cryptographic functionality and error paths. For your convenience the patches are available from: http://www.sisk.pl/kernel/patches/2.6.14-rc5-mm1/ I will very much appreciate any comments, remarks and suggestions. Greetings, Rafael
