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041a991fa7
per page = effectively 12.19 bytes per pv entry after overheads). Instead of using a shared UMA zone for 24 byte pv entries (two 8-byte tailq nodes, a 4 byte pointer, and a 4 byte address), we allocate a page at a time per process. This provides 336 pv entries per process (actually, per pmap address space) and eliminates one of the 8-byte tailq entries since we now can track per-process pv entries implicitly. The pointer to the pmap can be eliminated by doing address arithmetic to find the metadata on the page headers to find a single pointer shared by all 336 entries. There is an 11-int bitmap for the freelist of those 336 entries. This is mostly a mechanical conversion from amd64, except: * i386 has to allocate kvm and map the pages, amd64 has them outside of kvm * native word size is smaller, so bitmaps etc become 32 bit instead of 64 * no dump_add_page() etc stuff because they are in kvm always. * various pmap internals tweaks because pmap uses direct map on amd64 but on i386 it has to use sched_pin and temporary mappings. Also, sysctl vm.pmap.pv_entry_max and vm.pmap.shpgperproc are now dynamic sysctls. Like on amd64, i386 can now tune the pv entry limits without a recompile or reboot. This is important because of the following scenario. If you have a 1GB file (262144 pages) mmap()ed into 50 processes, that requires 13 million pv entries. At 24 bytes per pv entry, that is 314MB of ram and kvm, while at 12 bytes it is 157MB. A 157MB saving is significant. Test-run by: scottl (Thanks!) |
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| bin | ||
| contrib | ||
| crypto | ||
| etc | ||
| games | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| sys | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| ObsoleteFiles.inc | ||
| README | ||
| UPDATING | ||
This is the top level of the FreeBSD source directory. This file was last revised on: $FreeBSD$ For copyright information, please see the file COPYRIGHT in this directory (additional copyright information also exists for some sources in this tree - please see the specific source directories for more information). The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree, the most commonly used one being ``world'', which rebuilds and installs everything in the FreeBSD system from the source tree except the kernel, the kernel-modules and the contents of /etc. The ``buildkernel'' and ``installkernel'' targets build and install the kernel and the modules (see below). Please see the top of the Makefile in this directory for more information on the standard build targets and compile-time flags. Building a kernel is a somewhat more involved process, documentation for which can be found at: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html And in the config(8) man page. Note: If you want to build and install the kernel with the ``buildkernel'' and ``installkernel'' targets, you might need to build world before. More information is available in the handbook. The sample kernel configuration files reside in the sys/<arch>/conf sub-directory (assuming that you've installed the kernel sources), the file named GENERIC being the one used to build your initial installation kernel. The file NOTES contains entries and documentation for all possible devices, not just those commonly used. It is the successor of the ancient LINT file, but in contrast to LINT, it is not buildable as a kernel but a pure reference and documentation file. Source Roadmap: --------------- bin System/user commands. contrib Packages contributed by 3rd parties. crypto Cryptography stuff (see crypto/README). etc Template files for /etc. games Amusements. gnu Various commands and libraries under the GNU Public License. Please see gnu/COPYING* for more information. include System include files. kerberos5 Kerberos5 (Heimdal) package. lib System libraries. libexec System daemons. release Release building Makefile & associated tools. rescue Build system for statically linked /rescue utilities. sbin System commands. secure Cryptographic libraries and commands. share Shared resources. sys Kernel sources. tools Utilities for regression testing and miscellaneous tasks. usr.bin User commands. usr.sbin System administration commands. For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/synching.html