qemu /
qemu /
e3feb2cc224f61149a27f021042f5a4230bb1008 util: import GTree as QTree
The only reason to add this implementation is to control the memory allocator
used. Some users (e.g. TCG) cannot work reliably in multi-threaded
environments (e.g. forking in user-mode) with GTree's allocator, GSlice.
See https://gitlab.com/qemu-project/qemu/-/issues/285 for details.
Importing GTree is a temporary workaround until GTree migrates away
from GSlice.
This implementation is identical to that in glib v2.75.0, except that
we don't import recent additions to the API nor deprecated API calls,
none of which are used in QEMU.
I've imported tests from glib and added a benchmark just to
make sure that performance is similar. Note: it cannot be identical
because (1) we are not using GSlice, (2) we use different compilation flags
(e.g. -fPIC) and (3) we're linking statically.
$ cat /proc/cpuinfo| grep 'model name' | head -1
model name : AMD Ryzen 7 PRO 5850U with Radeon Graphics
$ echo '0' | sudo tee /sys/devices/system/cpu/cpufreq/boost
$ tests/bench/qtree-bench
Tree Op 32 1024 4096 131072 1048576
------------------------------------------------------------------------------------------------
GTree Lookup 83.23 43.08 25.31 19.40 16.22
QTree Lookup 113.42 (1.36x) 53.83 (1.25x) 28.38 (1.12x) 17.64 (0.91x) 13.04 (0.80x)
GTree Insert 44.23 29.37 25.83 19.49 17.03
QTree Insert 46.87 (1.06x) 25.62 (0.87x) 24.29 (0.94x) 16.83 (0.86x) 12.97 (0.76x)
GTree Remove 53.27 35.15 31.43 24.64 16.70
QTree Remove 57.32 (1.08x) 41.76 (1.19x) 38.37 (1.22x) 29.30 (1.19x) 15.07 (0.90x)
GTree RemoveAll 135.44 127.52 126.72 120.11 64.34
QTree RemoveAll 127.15 (0.94x) 110.37 (0.87x) 107.97 (0.85x) 97.13 (0.81x) 55.10 (0.86x)
GTree Traverse 277.71 276.09 272.78 246.72 98.47
QTree Traverse 370.33 (1.33x) 411.97 (1.49x) 400.23 (1.47x) 262.82 (1.07x) 78.52 (0.80x)
------------------------------------------------------------------------------------------------
As a sanity check, the same benchmark when Glib's version
is >= $glib_dropped_gslice_version (i.e. QTree == GTree):
Tree Op 32 1024 4096 131072 1048576
------------------------------------------------------------------------------------------------
GTree Lookup 82.72 43.09 24.18 19.73 16.09
QTree Lookup 81.82 (0.99x) 43.10 (1.00x) 24.20 (1.00x) 19.76 (1.00x) 16.26 (1.01x)
GTree Insert 45.07 29.62 26.34 19.90 17.18
QTree Insert 45.72 (1.01x) 29.60 (1.00x) 26.38 (1.00x) 19.71 (0.99x) 17.20 (1.00x)
GTree Remove 54.48 35.36 31.77 24.97 16.95
QTree Remove 54.46 (1.00x) 35.32 (1.00x) 31.77 (1.00x) 24.91 (1.00x) 17.15 (1.01x)
GTree RemoveAll 140.68 127.36 125.43 121.45 68.20
QTree RemoveAll 140.65 (1.00x) 127.64 (1.00x) 125.01 (1.00x) 121.73 (1.00x) 67.06 (0.98x)
GTree Traverse 278.68 276.05 266.75 251.65 104.93
QTree Traverse 278.31 (1.00x) 275.78 (1.00x) 266.42 (1.00x) 247.89 (0.99x) 104.58 (1.00x)
------------------------------------------------------------------------------------------------
Signed-off-by: Emilio Cota <cota@braap.org>
Message-Id: <20230205163758.416992-2-cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
9 files changed
