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| author |   Sven Schnelle <svens@linux.ibm.com> | 2020-04-28 09:52:23 +0200 |
|---|---|---|
| committer |   Vasily Gorbik <gor@linux.ibm.com> | 2020-08-26 18:47:21 +0200 |
| commit | 4bff8cb5450287e246d365b719148b2d9364c292 (patch) | |
| tree | 4cc4c378f7541d4b8fd080663d2f0847a24c2cfc /arch/s390/Kconfig | |
| parent | s390/checksum: coding style changes (diff) | |
| download | linux-dev-4bff8cb5450287e246d365b719148b2d9364c292.tar.xz linux-dev-4bff8cb5450287e246d365b719148b2d9364c292.zip | |
s390: convert to GENERIC_VDSO
Convert s390 to generic vDSO. There are a few special things on s390:
- vDSO can be called without a stack frame - glibc did this in the past.
So we need to allocate a stackframe on our own.
- The former assembly code used stcke to get the TOD clock and applied
time steering to it. We need to do the same in the new code. This is done
in the architecture specific __arch_get_hw_counter function. The steering
information is stored in an architecure specific area in the vDSO data.
- CPUCLOCK_VIRT is now handled with a syscall fallback, which might
be slower/less accurate than the old implementation.
The getcpu() function stays as an assembly function because there is no
generic implementation and the code is just a few lines.
Performance number from my system do 100 mio gettimeofday() calls:
Plain syscall: 8.6s
Generic VDSO: 1.3s
old ASM VDSO: 1s
So it's a bit slower but still much faster than syscalls.
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/Kconfig')
| -rw-r--r-- | arch/s390/Kconfig | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 3d86e12e8e3c..8a6121f93709 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -73,6 +73,7 @@ config S390 select ARCH_HAS_STRICT_MODULE_RWX select ARCH_HAS_SYSCALL_WRAPPER select ARCH_HAS_UBSAN_SANITIZE_ALL + select ARCH_HAS_VDSO_DATA select ARCH_HAVE_NMI_SAFE_CMPXCHG select ARCH_INLINE_READ_LOCK select ARCH_INLINE_READ_LOCK_BH @@ -118,6 +119,7 @@ config S390 select GENERIC_CPU_AUTOPROBE select GENERIC_CPU_VULNERABILITIES select GENERIC_FIND_FIRST_BIT + select GENERIC_GETTIMEOFDAY select GENERIC_SMP_IDLE_THREAD select GENERIC_TIME_VSYSCALL select HAVE_ALIGNED_STRUCT_PAGE if SLUB @@ -149,6 +151,7 @@ config S390 select HAVE_FUNCTION_TRACER select HAVE_FUTEX_CMPXCHG if FUTEX select HAVE_GCC_PLUGINS + select HAVE_GENERIC_VDSO select HAVE_KERNEL_BZIP2 select HAVE_KERNEL_GZIP select HAVE_KERNEL_LZ4 |