Release 8.0.0 new features

New VMM functionality at boot time

VMM increases the information about memory size and use that is issued at boot time. Formerly, the system issued this message:

   N bytes of memory are in the page pool

This message has been replaced by the following two messages:

   N bytes of general purpose memory are available
   N bytes of memory are available to cache file data

For example, the new boot time messages for memory might look like the following, on a large memory system:

   16910942208 bytes of memory were detected
   16910925824 bytes of memory are in use
   12615958528 bytes of general purpose memory are available
    4014080000 bytes of memory are available to cache file data
    4294967296 bytes of memory are dedicated

In this example, the system has 16GB of memory. Some 4GB is dedicated (that is, set aside for use by DSHM or PSE SHM), or SEGKMEM_PSE_BYTES. The remainder of the usable memory is classified as ``general purpose.'' However, only 3.75GB of it can hold file pages.

Without the VMM functionality installed, the boot messages for this very same system would have been the following:

   16910942208 bytes of memory were detected
   13115109376 bytes of memory are in use
    8589934592 bytes of memory are in the page pool
    4294967296 bytes of memory are dedicated

Note that 4GB of memory was wasted, because the general purpose memory was limited to 8GB. Also, only 4GB of dedicated memory was required (by the sum of the tunables DEDICATED_MEMORY and SEGKMEM_PSE_BYTES.

In addition, two new parameters are now recognized by the kernel at boot time. See boot(1M) and boot(4) for details on the use of these parameters:

CACHE_LINE=number: This parameter is used to optimize spacing between locks so that VMlocks end up separate cache lines. This reduces cache coherency traffic.
PAGE_BINS=number_of_bins: This parameter is used to optimize allocation of pages. The number of bins should correspond to the largest ``cache bank'' in the system.