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The current IFUNC selection is based on microbenchmarks in glibc. It should give the best performance for most workloads. But other choices may have better performance for a particular workload or on the hardware which wasn't available at the selection was made. The environment variable, GLIBC_TUNABLES=glibc.tune.ifunc=-xxx,yyy,-zzz...., can be used to enable CPU/ARCH feature yyy, disable CPU/ARCH feature yyy and zzz, where the feature name is case-sensitive and has to match the ones in cpu-features.h. It can be used by glibc developers to override the IFUNC selection to tune for a new processor or improve performance for a particular workload. It isn't intended for normal end users. NOTE: the IFUNC selection may change over time. Please check all multiarch implementations when experimenting. Also, GLIBC_TUNABLES=glibc.tune.x86_non_temporal_threshold=NUMBER is provided to set threshold to use non temporal store to NUMBER, GLIBC_TUNABLES=glibc.tune.x86_data_cache_size=NUMBER to set data cache size, GLIBC_TUNABLES=glibc.tune.x86_shared_cache_size=NUMBER to set shared cache size. * elf/dl-tunables.list (tune): Add ifunc, x86_non_temporal_threshold, x86_data_cache_size and x86_shared_cache_size. * manual/tunables.texi: Document glibc.tune.ifunc, glibc.tune.x86_data_cache_size, glibc.tune.x86_shared_cache_size and glibc.tune.x86_non_temporal_threshold. * sysdeps/unix/sysv/linux/x86/dl-sysdep.c: New file. * sysdeps/x86/cpu-tunables.c: Likewise. * sysdeps/x86/cacheinfo.c (init_cacheinfo): Check and get data cache size, shared cache size and non temporal threshold from cpu_features. * sysdeps/x86/cpu-features.c [HAVE_TUNABLES] (TUNABLE_NAMESPACE): New. [HAVE_TUNABLES] Include <unistd.h>. [HAVE_TUNABLES] Include <elf/dl-tunables.h>. [HAVE_TUNABLES] (TUNABLE_CALLBACK (set_ifunc)): Likewise. [HAVE_TUNABLES] (init_cpu_features): Use TUNABLE_GET to set IFUNC selection, data cache size, shared cache size and non temporal threshold. * sysdeps/x86/cpu-features.h (cpu_features): Add data_cache_size, shared_cache_size and non_temporal_threshold. |
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.. | ||
examples | ||
argp.texi | ||
arith.texi | ||
charset.texi | ||
check-safety.sh | ||
conf.texi | ||
contrib.texi | ||
creature.texi | ||
crypt.texi | ||
ctype.texi | ||
debug.texi | ||
dir | ||
errno.texi | ||
fdl-1.3.texi | ||
filesys.texi | ||
freemanuals.texi | ||
getopt.texi | ||
header.texi | ||
install-plain.texi | ||
install.texi | ||
intro.texi | ||
io.texi | ||
ipc.texi | ||
job.texi | ||
lang.texi | ||
lgpl-2.1.texi | ||
libc-texinfo.sh | ||
libc.texinfo | ||
libcbook.texi | ||
libdl.texi | ||
libm-err-tab.pl | ||
llio.texi | ||
locale.texi | ||
macros.texi | ||
maint.texi | ||
Makefile | ||
math.texi | ||
memory.texi | ||
message.texi | ||
nss.texi | ||
nsswitch.texi | ||
pattern.texi | ||
pipe.texi | ||
platform.texi | ||
probes.texi | ||
process.texi | ||
resource.texi | ||
search.texi | ||
setjmp.texi | ||
signal.texi | ||
socket.texi | ||
startup.texi | ||
stdio-fp.c | ||
stdio.texi | ||
string.texi | ||
summary.pl | ||
sysinfo.texi | ||
syslog.texi | ||
terminal.texi | ||
texinfo.tex | ||
texis.awk | ||
threads.texi | ||
time.texi | ||
tsort.awk | ||
tunables.texi | ||
users.texi | ||
xtract-typefun.awk |