diff options
| author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2020-08-18 20:19:17 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-12-03 17:01:11 +0300 |
| commit | b6254ced4da6cf28d49fbffe24ee4b3286dcb3f4 (patch) | |
| tree | b540b61c16700a38016b462239cef5ff6319de9a /arch/powerpc/Kconfig | |
| parent | 4d90eb97e292c7b14de8ba59fded35b340c73101 (diff) | |
| download | linux-b6254ced4da6cf28d49fbffe24ee4b3286dcb3f4.tar.xz | |
powerpc/signal: Don't manage floating point regs when no FPU
There is no point in copying floating point regs when there
is no FPU and MATH_EMULATION is not selected.
Create a new CONFIG_PPC_FPU_REGS bool that is selected by
CONFIG_MATH_EMULATION and CONFIG_PPC_FPU, and use it to
opt out everything related to fp_state in thread_struct.
The asm const used only by fpu.S are opted out with CONFIG_PPC_FPU
as fpu.S build is conditionnal to CONFIG_PPC_FPU.
The following app spends approx 8.1 seconds system time on an 8xx
without the patch, and 7.0 seconds with the patch (13.5% reduction).
On an 832x, it spends approx 2.6 seconds system time without
the patch and 2.1 seconds with the patch (19% reduction).
void sigusr1(int sig) { }
int main(int argc, char **argv)
{
int i = 100000;
signal(SIGUSR1, sigusr1);
for (;i--;)
raise(SIGUSR1);
exit(0);
}
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7569070083e6cd5b279bb5023da601aba3c06f3c.1597770847.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch/powerpc/Kconfig')
| -rw-r--r-- | arch/powerpc/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index aad8532a718e..8d12da224cb9 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -422,6 +422,7 @@ config HUGETLB_PAGE_SIZE_VARIABLE config MATH_EMULATION bool "Math emulation" depends on 4xx || PPC_8xx || PPC_MPC832x || BOOKE + select PPC_FPU_REGS help Some PowerPC chips designed for embedded applications do not have a floating-point unit and therefore do not implement the |