FreeBSD src
a2801b7731
have been maintained, and that is still the default. A new sysctl
variable "vfs.timestamp_precision" can be used to enable higher
levels of precision:
0 = seconds only; nanoseconds zeroed (default).
1 = seconds and nanoseconds, accurate within 1/HZ.
2 = seconds and nanoseconds, truncated to microseconds.
>=3 = seconds and nanoseconds, maximum precision.
Level 1 uses getnanotime(), which is fast but can be wrong by up
to 1/HZ. Level 2 uses microtime(). It might be desirable for
consistency with utimes() and friends, which take timeval structures
rather than timespecs. Level 3 uses nanotime() for the higest
precision.
I benchmarked levels 0, 1, and 3 by copying a 550 MB tree with
"cpio -pdu". There was almost negligible difference in the system
times -- much less than 1%, and less than the variation among
multiple runs at the same level. Bruce Evans dreamed up a torture
test involving 1-byte reads with intervening fstat() calls, but
the cpio test seems more realistic to me.
This feature is currently implemented only for the UFS (FFS and
MFS) filesystems. But I think it should be easy to support it in
the others as well.
An earlier version of this was reviewed by Bruce. He's not to
blame for any breakage I've introduced since then.
Reviewed by: bde (an earlier version of the code)
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| bin | ||
| contrib | ||
| crypto | ||
| etc | ||
| games | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| kerberosIV | ||
| lib | ||
| libexec | ||
| release | ||
| sbin | ||
| secure | ||
| share | ||
| sys | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| COPYRIGHT | ||
| Makefile | ||
| Makefile.inc0 | ||
| Makefile.inc1 | ||
| Makefile.upgrade | ||
| README | ||
| UPDATING | ||
This is the top level of the FreeBSD source directory. This file was last revised on: $Id: README,v 1.13 1998/09/13 09:38:34 markm Exp $ 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 and the contents of /etc. 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 with config(8) is a somewhat more involved process, documentation for which can be found at: http://www.freebsd.org/handbook/kernelconfig.html And in the config(8) man page. The sample kernel configuration files reside in the sys/i386/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 LINT contains entries for all possible devices, not just those commonly used, and is meant more as a general reference than an actual kernel configuration file (a kernel built from it wouldn't even run). Source Roadmap: --------------- bin System/User commands. contrib Packages contributed by 3rd parties. crypto Export controlled 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. kerberosIV Kerberos package. lib System libraries. libexec System daemons. release Release building Makefile & associated tools. sbin System commands. secure DES and DES-related utilities - NOT FOR EXPORT! 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/handbook/synching.html