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4fec3a8161
freebsd-skq/lib
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ed 4fec3a8161 Let tsearch()/tdelete() use an AVL tree. 
The existing implementations of POSIX tsearch() and tdelete() don't
attempt to perform any balancing at all. Testing reveals that inserting
100k nodes into a tree sequentially takes approximately one minute on my
system.

Though most other BSDs also don't use any balanced tree internally, C
libraries like glibc and musl do provide better implementations. glibc
uses a red-black tree and musl uses an AVL tree.

Red-black trees have the advantage over AVL trees that they only require
O(1) rotations after insertion and deletion, but have the disadvantage
that the tree has a maximum depth of 2*log2(n) instead of 1.44*log2(n).
My take is that it's better to focus on having a lower maximum depth,
for the reason that in the case of tsearch() the invocation of the
comparator likely dominates the running time.

This change replaces the tsearch() and tdelete() functions by versions
that create an AVL tree. Compared to musl's implementation, this version
is different in two different ways:

- We don't keep track of heights; just balances. This is sufficient.
  This has the advantage that it reduces the number of nodes that are
  being accessed. Storing heights requires us to also access all of the
  siblings along the path.

- Don't use any recursion at all. We know that the tree cannot 2^64
  elements in size, so the height of the tree can never be larger than
  96. Use a 128-bit bitmask to keep track of the path that is computed.
  This allows us to iterate over the same path twice, meaning we can
  apply rotations from top to bottom.

Inserting 100k nodes into a tree now only takes 0.015 seconds. Insertion
seems to be twice as fast as glibc, whereas deletion has about the same
performance. Unlike glibc, it uses a fixed amount of memory.

I also experimented with both recursive and iterative bottom-up
implementations of the same algorithm. This iterative top-down version
performs similar to the recursive bottom-up version in terms of speed
and code size.

For some reason, the iterative bottom-up algorithm was actually 30%
faster for deletion, but has a quadratic memory complexity to keep track
of all the parent pointers.

Reviewed by:	jilles
Obtained from:	https://github.com/NuxiNL/cloudlibc
Differential Revision:	https://reviews.freebsd.org/D4412
2015-12-22 18:12:11 +00:00
..
atf META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
clang META MODE: Update dependencies with 'the-lot' and add missing directories. 2015-12-01 05:23:19 +00:00
csu Start support for the RISC-V 64-bit architecture developed by UC Berkeley. 2015-12-11 22:55:23 +00:00
lib80211 Minor spelling, mdoc and style cleanup. 2015-12-15 10:24:48 +00:00
libalias META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libarchive Don't override LIB*DIR variables from src.libnames.mk. 2015-12-01 22:20:04 +00:00
libauditd Don't override LIB*DIR variables from src.libnames.mk. 2015-12-01 22:03:40 +00:00
libbegemot META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libblocksruntime META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libbluetooth META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libbsdstat META MODE: Update dependencies with 'the-lot' and add missing directories. 2015-12-01 05:23:19 +00:00
libbsm Add au_notify.2 and MLINKs (added in OpenBSM 1.2 alpha 4). 2015-12-18 09:50:24 +00:00
libbsnmp META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libbz2 META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libc Let tsearch()/tdelete() use an AVL tree. 2015-12-22 18:12:11 +00:00
libc_nonshared Add META_MODE support. 2015-06-13 19:20:56 +00:00
libc++ Replace ln -s calls with INSTALL_SYMLINK 2015-12-04 03:17:14 +00:00
libcalendar META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libcam META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libcapsicum META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libcasper META MODE: Update dependencies with 'the-lot' and add missing directories. 2015-12-01 05:23:19 +00:00
libclang_rt META MODE: Update dependencies with 'the-lot' and add missing directories. 2015-12-01 05:23:19 +00:00
libcom_err META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libcompat Add META_MODE support. 2015-06-13 19:20:56 +00:00
libcompiler_rt Merge ^/head r288197 through r288456. 2015-10-01 19:02:45 +00:00
libcrypt Enable libcrypt tests. 2015-12-01 21:25:18 +00:00
libcuse Make CUSE usable with platforms where the size of "unsigned long" is 2015-12-22 09:55:44 +00:00
libcxxrt META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libdevctl META MODE: Update dependencies with 'the-lot' and add missing directories. 2015-12-01 05:23:19 +00:00
libdevinfo META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libdevstat META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libdpv META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libdwarf META MODE: Fix 'make bootstrap-tools'. 2015-11-25 19:44:51 +00:00
libedit META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libefi use .Mt to mark up email addresses consistently (part3) 2014-06-23 08:23:05 +00:00
libelf Correct r291566 for defining SHLIBDIR. 2015-12-01 16:08:38 +00:00
libelftc Pay attention to MK_ELFTOOLCHAIN_TOOLS so we build the desired tools. 2015-06-15 20:11:15 +00:00
libevent META MODE: Update dependencies with 'the-lot' and add missing directories. 2015-12-01 05:23:19 +00:00
libexecinfo META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libexpat META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libfetch As a followup to r292330, standardize on size_t and add a few comments. 2015-12-16 09:20:45 +00:00
libfigpar META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libgeom META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libgpio META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libgssapi META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libiconv_modules META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libipsec META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libjail META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libkiconv META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libkvm Add support to libkvm for reading vmcores from other architectures. 2015-11-27 18:58:26 +00:00
libldns META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
liblzma META MODE: Fix 'make bootstrap-tools'. 2015-11-25 19:44:51 +00:00
libmagic META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libmd META MODE: Remove unneeded libmd.host dependency for xinstall.host. 2015-11-25 19:44:55 +00:00
libmemstat META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libmilter META MODE: Don't create .meta files when symlinking sources into the obj directory. 2015-11-25 19:44:43 +00:00
libmp META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libmt META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libnandfs META MODE: Connect MK_NAND directories. 2015-12-02 05:31:01 +00:00
libnetbsd Fix spelling error. 2015-11-05 01:54:38 +00:00
libnetgraph META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libngatm META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libnv META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libopenbsd Remove NO_WERROR, after fix from r292023. 2015-12-09 19:25:45 +00:00
libopie META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libpam DIRDEPS_BUILD: Update dependencies. 2015-12-07 23:53:01 +00:00
libpcap META MODE: Don't create .meta files when symlinking sources into the obj directory. 2015-11-25 19:44:43 +00:00
libpjdlog META MODE: Update dependencies with 'the-lot' and add missing directories. 2015-12-01 05:23:19 +00:00
libpmc Add support for Intel Skylake and Intel Broadwell PMC's. The Broadwell PMC's have been 2015-11-30 17:35:49 +00:00
libproc Fix LDADD/DPADD that should be LIBADD. 2015-12-04 03:17:47 +00:00
libprocstat META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libradius META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
librpcsec_gss META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
librpcsvc META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
librt Unbreak symbol versioning. I have no idea when it was broken, but it's been 2015-11-29 06:14:51 +00:00
librtld_db META MODE: Rework circular dependency guard for librtld_db/libproc. 2015-11-25 19:13:35 +00:00
libsbuf META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libsdp META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libsm META MODE: Don't create .meta files when symlinking sources into the obj directory. 2015-11-25 19:44:43 +00:00
libsmb META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libsmdb META MODE: Don't create .meta files when symlinking sources into the obj directory. 2015-11-25 19:44:43 +00:00
libsmutil META MODE: Don't create .meta files when symlinking sources into the obj directory. 2015-11-25 19:44:43 +00:00
libsqlite3 META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libstand Allow dhcp/bootp server-provided values to be overriden from environment 2015-12-22 03:02:52 +00:00
libstdbuf META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libstdthreads META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libsysdecode Start on a new library (libsysdecode) that provides routines for decoding 2015-12-15 00:05:07 +00:00
libtacplus Add META_MODE support. 2015-06-13 19:20:56 +00:00
libtelnet Add META_MODE support. 2015-06-13 19:20:56 +00:00
libthr libthr: Don't use both __sys_open() and __sys_openat(). 2015-12-20 16:33:56 +00:00
libthread_db META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libucl META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libufs META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libugidfw META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libulog META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libunbound META MODE: Update dependencies with 'the-lot' and add missing directories. 2015-12-01 05:23:19 +00:00
libusb META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libusbhid META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libutil META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libvgl META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libvmmapi META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libwrap Use LIBEXECDIR for /usr/libexec. 2015-11-26 01:14:40 +00:00
libxo META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
liby Add META_MODE support. 2015-06-13 19:20:56 +00:00
libypclnt META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
libz META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
msun Integrate the remaining tools/regression/lib/msun testcases into the 2015-12-20 05:06:44 +00:00
ncurses META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host. 2015-11-25 19:10:28 +00:00
tests Refactor the test/ Makefiles after recent changes to bsd.test.mk (r289158) and 2015-10-12 08:16:03 +00:00
Makefile Make the building of libsmb and mount_smbfs unconditional, now that r292552 2015-12-21 17:41:08 +00:00
Makefile.inc