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Correct L3 Detection #37

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Merged
malb merged 4 commits into from
Dec 4, 2025
Merged

Correct L3 Detection #37

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64c3575
we never actually set L3
malb Oct 13, 2025
f4fb05e
fix a compiler warning
malb Oct 13, 2025
b95a690
sysctl reads L3 cache size, too
malb Oct 20, 2025
e04ab74
next attempt at detecting L3
malb Nov 9, 2025
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112 changes: 64 additions & 48 deletions m4/ax_cache_size.m4
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Original file line number Diff line number Diff line change
Expand Up @@ -41,8 +41,9 @@ AC_DEFUN([AX_CACHE_SIZE],

ax_l1_size=
ax_l2_size=
ax_l3_size=

#Check if the variable is present
# Linux sysfs path
if test -e /sys/devices/system/cpu/cpu0/cache/index0/size; then
for idx in `seq 0 3`; do
if test -e /sys/devices/system/cpu/cpu0/cache/index$idx/size ; then
Expand All @@ -57,63 +58,78 @@ AC_DEFUN([AX_CACHE_SIZE],
ax_l3_size=$CPU0_L3_CACHE

else
if test "x$ax_cv_cpu_vendor" != "xUnknown"; then
#Or use CPUID
AX_GCC_X86_CPUID(0x80000000)
cpu_exthigh=`echo $ax_cv_gcc_x86_cpuid_0x80000000 | cut -d ":" -f 1`
if test "x$cpu_exthi" \> "x80000004"; then
AX_GCC_X86_CPUID(0x80000005) # For L1 cache
l1_hexval=`echo $ax_cv_gcc_x86_cpuid_0x80000005 | cut -d ":" -f 4`
ax_l1_size=$((0x$l1_hexval >> 24))
fi
# Try CPUID (mostly for Linux without sysfs or during cross-compilation)
if test "x$ax_cv_cpu_vendor" != "xIntel"; then
AX_GCC_X86_CPUID(0x80000000)
cpu_exthigh=`echo $ax_cv_gcc_x86_cpuid_0x80000000 | cut -d ":" -f 1`
if test "x$cpu_exthigh" \> "x80000004"; then
AX_GCC_X86_CPUID(0x80000005)
l1_hexval=`echo $ax_cv_gcc_x86_cpuid_0x80000005 | cut -d ":" -f 4`
ax_l1_size=$((0x$l1_hexval >> 24))
fi

if test "x$cpu_exthigh" \> "x80000005"; then
AX_GCC_X86_CPUID(0x80000006)
l2_hexval=`echo $ax_cv_gcc_x86_cpuid_0x80000006 | cut -d ":" -f 3`
ax_l2_size=$((0x$l2_hexval >> 16))

if test "x$cpu_exthi" \> "x80000005"; then
AX_GCC_X86_CPUID(0x80000006) # For L2 cache
l2_hexval=`echo $ax_cv_gcc_x86_cpuid_0x80000006 | cut -d ":" -f 3`
ax_l2_size=$((0x$l2_hexval >> 16))
# L3 info in EDX (bits 31:18) → 512-byte blocks (AMD only)
l3_hexval=`echo $ax_cv_gcc_x86_cpuid_0x80000006 | cut -d ":" -f 4`
ax_l3_size=$(( (0x$l3_hexval >> 18) * 512 ))
fi
fi

if test "x$cpu_exthi" \> "x80000005"; then
AX_GCC_X86_CPUID(0x80000006) # For L3 cache
l2_hexval=`echo $ax_cv_gcc_x86_cpuid_0x80000006 | cut -d ":" -f 4`
ax_l2_size=$((0x$l2_hexval >> 18))*512
# sysctl fallback
sysctl_exe=
if test -x /usr/sbin/sysctl; then
sysctl_exe=/usr/sbin/sysctl
elif test -x /sbin/sysctl; then
sysctl_exe=/sbin/sysctl
fi

fi

#Or use sysctl
sysctl_exe=
if test -x /usr/sbin/sysctl ; then
sysctl_exe=/usr/sbin/sysctl
elif test -x /sbin/sysctl ; then
sysctl_exe=/sbin/sysctl
fi
if test -n "$sysctl_exe"; then
if test -z "$ax_l2_size" -o "$ax_l2_size" = "0"; then
sysctl_out=`$sysctl_exe -n hw.l2cachesize 2>/dev/null`;
if test ! -z "$sysctl_out"; then
ax_l2_size=$(($sysctl_out / 1024))
fi;

fi
if test -z "$ax_l1_size" -o "$ax_l1_size" = "0" ; then
sysctl_out=`$sysctl_exe -n hw.l1dcachesize 2>/dev/null`;
if test ! -z "$sysctl_out"; then
ax_l1_size=$(($sysctl_out / 1024))
fi;
fi
if test -z "$ax_l1_size" -o "ax_l1_size" = "0" ; then
sysctl_out=`$sysctl_exe -n hw.l1cachesize 2>/dev/null`;
if test ! -z "$sysctl_out"; then
ax_l1_size=$(($sysctl_out / 1024))
fi;
if test -n "$sysctl_exe"; then
# L1
if test -z "$ax_l1_size" -o "$ax_l1_size" = "0"; then
sysctl_out=`$sysctl_exe -n hw.l1dcachesize 2>/dev/null`
if test -n "$sysctl_out"; then
ax_l1_size=$(($sysctl_out / 1024))
fi
fi
if test -z "$ax_l1_size" -o "$ax_l1_size" = "0"; then
sysctl_out=`$sysctl_exe -n hw.l1icachesize 2>/dev/null`
if test -n "$sysctl_out"; then
ax_l1_size=$(($sysctl_out / 1024))
fi
fi
if test -z "$ax_l1_size" -o "$ax_l1_size" = "0"; then
sysctl_out=`$sysctl_exe -n hw.l1cachesize 2>/dev/null`
if test -n "$sysctl_out"; then
ax_l1_size=$(($sysctl_out / 1024))
fi
fi

# L2
if test -z "$ax_l2_size" -o "$ax_l2_size" = "0"; then
sysctl_out=`$sysctl_exe -n hw.l2cachesize 2>/dev/null`
if test -n "$sysctl_out"; then
ax_l2_size=$(($sysctl_out / 1024))
fi
fi

# L3
if test -z "$ax_l3_size" -o "$ax_l3_size" = "0"; then
sysctl_out=`$sysctl_exe -n hw.l3cachesize 2>/dev/null`
if test -n "$sysctl_out"; then
ax_l3_size=$(($sysctl_out / 1024))
fi
fi
fi
fi
fi

# Final fallbacks
test -z "$ax_l1_size" && ax_l1_size=0
test -z "$ax_l2_size" && ax_l2_size=0
test -z "$ax_l3_size" && ax_l3_size=$ax_l2_size
test -z "$ax_l3_size" && ax_l3_size=0

# Keep only digits if there is a unit (ie 1024K -> 1024) and convert in Bytes
AC_MSG_CHECKING(the L1 cache size)
Expand Down
2 changes: 1 addition & 1 deletion m4ri/misc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -138,7 +138,7 @@ typedef uint64_t word;
* \brief The number of bits in a word.
*/

static int const m4ri_radix = 64;
#define m4ri_radix 64

/**
* \brief The number one as a word.
Expand Down