The only caller of this code (time_stats) always knows the weights and
whether or not any information has been collected. Pass this
information into the mean and variance code so that it doesn't have to
store that information. This reduces the structure size from 24 to 16
bytes, which shrinks each time_stats counter to 192 bytes from 208.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
The gcc compiler on paric does support the __int128 type, although the
architecture does not have native 128-bit support.
The effect is, that the bcachefs u128_square() function will pull in the
libgcc __multi3() helper, which breaks the kernel build when bcachefs is
built as module since this function isn't currently exported in
arch/parisc/kernel/parisc_ksyms.c.
The build failure can be seen in the latest debian kernel build at:
https://buildd.debian.org/status/fetch.php?pkg=linux&arch=hppa&ver=6.7.1-1%7Eexp1&stamp=1706132569&raw=0
We prefer to not export that symbol, so fall back to the optional 64-bit
implementation provided by bcachefs and thus avoid usage of __multi3().
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Add some more tests that test conventional and weighted mean
simultaneously, and with a table of values that represents events that
we'll be using this to look for so we can verify-by-eyeball that the
output looks sane.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This module provides a fast 64bit implementation of basic statistics
functions, including mean, variance and standard deviation in both
weighted and unweighted variants, the unweighted variant has a 32bit
limitation per sample to prevent overflow when squaring.
Signed-off-by: Daniel Hill <daniel@gluo.nz>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
