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Linux 5.0 compat: Disable vector instructions on 5.0+ kernels The 5.0 kernel no longer exports the functions we need to do vector (SSE/SSE2/SSE3/AVX...) instructions. Disable vector-based checksum algorithms when building against those kernels. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259
2019-01-12 05:01:28 +03:00
dnl #
dnl # Handle differences in kernel FPU code.
Support for vectorized algorithms on x86 This is initial support for x86 vectorized implementations of ZFS parity and checksum algorithms. For the compilation phase, configure step checks if toolchain supports relevant instruction sets. Each implementation must ensure that the code is not passed to compiler if relevant instruction set is not supported. For this purpose, following new defines are provided if instruction set is supported: - HAVE_SSE, - HAVE_SSE2, - HAVE_SSE3, - HAVE_SSSE3, - HAVE_SSE4_1, - HAVE_SSE4_2, - HAVE_AVX, - HAVE_AVX2. For detecting if an instruction set can be used in runtime, following functions are provided in (include/linux/simd_x86.h): - zfs_sse_available() - zfs_sse2_available() - zfs_sse3_available() - zfs_ssse3_available() - zfs_sse4_1_available() - zfs_sse4_2_available() - zfs_avx_available() - zfs_avx2_available() - zfs_bmi1_available() - zfs_bmi2_available() These function should be called once, on module load, or initialization. They are safe to use from user and kernel space. If an implementation is using more than single instruction set, both compiler and runtime support for all relevant instruction sets should be checked. Kernel fpu methods: - kfpu_begin() - kfpu_end() Use __get_cpuid_max and __cpuid_count from <cpuid.h> Both gcc and clang have support for these. They also handle ebx register in case it is used for PIC code. Signed-off-by: Gvozden Neskovic <neskovic@gmail.com> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Chunwei Chen <tuxoko@gmail.com> Closes #4381
2016-02-29 21:42:27 +03:00
dnl #
Linux 5.0 compat: Disable vector instructions on 5.0+ kernels The 5.0 kernel no longer exports the functions we need to do vector (SSE/SSE2/SSE3/AVX...) instructions. Disable vector-based checksum algorithms when building against those kernels. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259
2019-01-12 05:01:28 +03:00
dnl # Kernel
Linux 5.0 compat: SIMD compatibility Restore the SIMD optimization for 4.19.38 LTS, 4.14.120 LTS, and 5.0 and newer kernels. This is accomplished by leveraging the fact that by definition dedicated kernel threads never need to concern themselves with saving and restoring the user FPU state. Therefore, they may use the FPU as long as we can guarantee user tasks always restore their FPU state before context switching back to user space. For the 5.0 and 5.1 kernels disabling preemption and local interrupts is sufficient to allow the FPU to be used. All non-kernel threads will restore the preserved user FPU state. For 5.2 and latter kernels the user FPU state restoration will be skipped if the kernel determines the registers have not changed. Therefore, for these kernels we need to perform the additional step of saving and restoring the FPU registers. Invalidating the per-cpu global tracking the FPU state would force a restore but that functionality is private to the core x86 FPU implementation and unavailable. In practice, restricting SIMD to kernel threads is not a major restriction for ZFS. The vast majority of SIMD operations are already performed by the IO pipeline. The remaining cases are relatively infrequent and can be handled by the generic code without significant impact. The two most noteworthy cases are: 1) Decrypting the wrapping key for an encrypted dataset, i.e. `zfs load-key`. All other encryption and decryption operations will use the SIMD optimized implementations. 2) Generating the payload checksums for a `zfs send` stream. In order to avoid making any changes to the higher layers of ZFS all of the `*_get_ops()` functions were updated to take in to consideration the calling context. This allows for the fastest implementation to be used as appropriate (see kfpu_allowed()). The only other notable instance of SIMD operations being used outside a kernel thread was at module load time. This code was moved in to a taskq in order to accommodate the new kernel thread restriction. Finally, a few other modifications were made in order to further harden this code and facilitate testing. They include updating each implementations operations structure to be declared as a constant. And allowing "cycle" to be set when selecting the preferred ops in the kernel as well as user space. Reviewed-by: Tony Hutter <hutter2@llnl.gov> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #8754 Closes #8793 Closes #8965
2019-07-12 19:31:20 +03:00
dnl # 5.2: The fpu->initialized flag was replaced by TIF_NEED_FPU_LOAD.
dnl # HAVE_KERNEL_TIF_NEED_FPU_LOAD
dnl #
dnl # 5.0: As an optimization SIMD operations performed by kernel
dnl # threads can skip saving and restoring their FPU context.
dnl # Wrappers have been introduced to determine the running
dnl # context and use either the SIMD or generic implementation.
dnl # This change was made to the 4.19.38 and 4.14.120 LTS kernels.
dnl # HAVE_KERNEL_FPU_INITIALIZED
Linux 5.0 compat: Disable vector instructions on 5.0+ kernels The 5.0 kernel no longer exports the functions we need to do vector (SSE/SSE2/SSE3/AVX...) instructions. Disable vector-based checksum algorithms when building against those kernels. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259
2019-01-12 05:01:28 +03:00
dnl #
dnl # 4.2: Use __kernel_fpu_{begin,end}()
dnl # HAVE_UNDERSCORE_KERNEL_FPU & KERNEL_EXPORTS_X86_FPU
dnl #
dnl # Pre-4.2: Use kernel_fpu_{begin,end}()
dnl # HAVE_KERNEL_FPU & KERNEL_EXPORTS_X86_FPU
Support for vectorized algorithms on x86 This is initial support for x86 vectorized implementations of ZFS parity and checksum algorithms. For the compilation phase, configure step checks if toolchain supports relevant instruction sets. Each implementation must ensure that the code is not passed to compiler if relevant instruction set is not supported. For this purpose, following new defines are provided if instruction set is supported: - HAVE_SSE, - HAVE_SSE2, - HAVE_SSE3, - HAVE_SSSE3, - HAVE_SSE4_1, - HAVE_SSE4_2, - HAVE_AVX, - HAVE_AVX2. For detecting if an instruction set can be used in runtime, following functions are provided in (include/linux/simd_x86.h): - zfs_sse_available() - zfs_sse2_available() - zfs_sse3_available() - zfs_ssse3_available() - zfs_sse4_1_available() - zfs_sse4_2_available() - zfs_avx_available() - zfs_avx2_available() - zfs_bmi1_available() - zfs_bmi2_available() These function should be called once, on module load, or initialization. They are safe to use from user and kernel space. If an implementation is using more than single instruction set, both compiler and runtime support for all relevant instruction sets should be checked. Kernel fpu methods: - kfpu_begin() - kfpu_end() Use __get_cpuid_max and __cpuid_count from <cpuid.h> Both gcc and clang have support for these. They also handle ebx register in case it is used for PIC code. Signed-off-by: Gvozden Neskovic <neskovic@gmail.com> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Chunwei Chen <tuxoko@gmail.com> Closes #4381
2016-02-29 21:42:27 +03:00
dnl #
AC_DEFUN([ZFS_AC_KERNEL_FPU], [
kernel_fpu fixes This patch fixes a few issues when detecting which kernel_fpu functions are available. - Use kernel_fpu_begin() if it's exported on newer kernels. - Use ZFS_LINUX_TRY_COMPILE_SYMBOL() to choose the right kernel_fpu function when using --enable-linux-builtin. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259 Closes #8363
2019-03-07 03:03:03 +03:00
AC_MSG_CHECKING([which kernel_fpu header to use])
Support for vectorized algorithms on x86 This is initial support for x86 vectorized implementations of ZFS parity and checksum algorithms. For the compilation phase, configure step checks if toolchain supports relevant instruction sets. Each implementation must ensure that the code is not passed to compiler if relevant instruction set is not supported. For this purpose, following new defines are provided if instruction set is supported: - HAVE_SSE, - HAVE_SSE2, - HAVE_SSE3, - HAVE_SSSE3, - HAVE_SSE4_1, - HAVE_SSE4_2, - HAVE_AVX, - HAVE_AVX2. For detecting if an instruction set can be used in runtime, following functions are provided in (include/linux/simd_x86.h): - zfs_sse_available() - zfs_sse2_available() - zfs_sse3_available() - zfs_ssse3_available() - zfs_sse4_1_available() - zfs_sse4_2_available() - zfs_avx_available() - zfs_avx2_available() - zfs_bmi1_available() - zfs_bmi2_available() These function should be called once, on module load, or initialization. They are safe to use from user and kernel space. If an implementation is using more than single instruction set, both compiler and runtime support for all relevant instruction sets should be checked. Kernel fpu methods: - kfpu_begin() - kfpu_end() Use __get_cpuid_max and __cpuid_count from <cpuid.h> Both gcc and clang have support for these. They also handle ebx register in case it is used for PIC code. Signed-off-by: Gvozden Neskovic <neskovic@gmail.com> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Chunwei Chen <tuxoko@gmail.com> Closes #4381
2016-02-29 21:42:27 +03:00
ZFS_LINUX_TRY_COMPILE([
kernel_fpu fixes This patch fixes a few issues when detecting which kernel_fpu functions are available. - Use kernel_fpu_begin() if it's exported on newer kernels. - Use ZFS_LINUX_TRY_COMPILE_SYMBOL() to choose the right kernel_fpu function when using --enable-linux-builtin. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259 Closes #8363
2019-03-07 03:03:03 +03:00
#include <linux/module.h>
#include <asm/fpu/api.h>
],[
],[
Minor style cleanup Resolve an assortment of style inconsistencies including use of white space, typos, capitalization, and line wrapping. There is no functional change. Reviewed-by: Tony Hutter <hutter2@llnl.gov> Reviewed-by: George Melikov <mail@gmelikov.ru> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #9030
2019-07-17 03:22:31 +03:00
AC_DEFINE(HAVE_KERNEL_FPU_API_HEADER, 1,
[kernel has asm/fpu/api.h])
kernel_fpu fixes This patch fixes a few issues when detecting which kernel_fpu functions are available. - Use kernel_fpu_begin() if it's exported on newer kernels. - Use ZFS_LINUX_TRY_COMPILE_SYMBOL() to choose the right kernel_fpu function when using --enable-linux-builtin. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259 Closes #8363
2019-03-07 03:03:03 +03:00
AC_MSG_RESULT(asm/fpu/api.h)
],[
AC_MSG_RESULT(i387.h & xcr.h)
])
AC_MSG_CHECKING([which kernel_fpu function to use])
ZFS_LINUX_TRY_COMPILE_SYMBOL([
#include <linux/module.h>
#ifdef HAVE_KERNEL_FPU_API_HEADER
#include <asm/fpu/api.h>
#else
Linux 5.0 compat: Disable vector instructions on 5.0+ kernels The 5.0 kernel no longer exports the functions we need to do vector (SSE/SSE2/SSE3/AVX...) instructions. Disable vector-based checksum algorithms when building against those kernels. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259
2019-01-12 05:01:28 +03:00
#include <asm/i387.h>
#include <asm/xcr.h>
kernel_fpu fixes This patch fixes a few issues when detecting which kernel_fpu functions are available. - Use kernel_fpu_begin() if it's exported on newer kernels. - Use ZFS_LINUX_TRY_COMPILE_SYMBOL() to choose the right kernel_fpu function when using --enable-linux-builtin. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259 Closes #8363
2019-03-07 03:03:03 +03:00
#endif
MODULE_LICENSE("$ZFS_META_LICENSE");
Support for vectorized algorithms on x86 This is initial support for x86 vectorized implementations of ZFS parity and checksum algorithms. For the compilation phase, configure step checks if toolchain supports relevant instruction sets. Each implementation must ensure that the code is not passed to compiler if relevant instruction set is not supported. For this purpose, following new defines are provided if instruction set is supported: - HAVE_SSE, - HAVE_SSE2, - HAVE_SSE3, - HAVE_SSSE3, - HAVE_SSE4_1, - HAVE_SSE4_2, - HAVE_AVX, - HAVE_AVX2. For detecting if an instruction set can be used in runtime, following functions are provided in (include/linux/simd_x86.h): - zfs_sse_available() - zfs_sse2_available() - zfs_sse3_available() - zfs_ssse3_available() - zfs_sse4_1_available() - zfs_sse4_2_available() - zfs_avx_available() - zfs_avx2_available() - zfs_bmi1_available() - zfs_bmi2_available() These function should be called once, on module load, or initialization. They are safe to use from user and kernel space. If an implementation is using more than single instruction set, both compiler and runtime support for all relevant instruction sets should be checked. Kernel fpu methods: - kfpu_begin() - kfpu_end() Use __get_cpuid_max and __cpuid_count from <cpuid.h> Both gcc and clang have support for these. They also handle ebx register in case it is used for PIC code. Signed-off-by: Gvozden Neskovic <neskovic@gmail.com> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Chunwei Chen <tuxoko@gmail.com> Closes #4381
2016-02-29 21:42:27 +03:00
],[
Linux 5.0 compat: Disable vector instructions on 5.0+ kernels The 5.0 kernel no longer exports the functions we need to do vector (SSE/SSE2/SSE3/AVX...) instructions. Disable vector-based checksum algorithms when building against those kernels. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259
2019-01-12 05:01:28 +03:00
kernel_fpu_begin();
kernel_fpu_end();
kernel_fpu fixes This patch fixes a few issues when detecting which kernel_fpu functions are available. - Use kernel_fpu_begin() if it's exported on newer kernels. - Use ZFS_LINUX_TRY_COMPILE_SYMBOL() to choose the right kernel_fpu function when using --enable-linux-builtin. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259 Closes #8363
2019-03-07 03:03:03 +03:00
], [kernel_fpu_begin], [arch/x86/kernel/fpu/core.c], [
Linux 5.0 compat: Disable vector instructions on 5.0+ kernels The 5.0 kernel no longer exports the functions we need to do vector (SSE/SSE2/SSE3/AVX...) instructions. Disable vector-based checksum algorithms when building against those kernels. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259
2019-01-12 05:01:28 +03:00
AC_MSG_RESULT(kernel_fpu_*)
Minor style cleanup Resolve an assortment of style inconsistencies including use of white space, typos, capitalization, and line wrapping. There is no functional change. Reviewed-by: Tony Hutter <hutter2@llnl.gov> Reviewed-by: George Melikov <mail@gmelikov.ru> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #9030
2019-07-17 03:22:31 +03:00
AC_DEFINE(HAVE_KERNEL_FPU, 1,
[kernel has kernel_fpu_* functions])
AC_DEFINE(KERNEL_EXPORTS_X86_FPU, 1,
[kernel exports FPU functions])
Support for vectorized algorithms on x86 This is initial support for x86 vectorized implementations of ZFS parity and checksum algorithms. For the compilation phase, configure step checks if toolchain supports relevant instruction sets. Each implementation must ensure that the code is not passed to compiler if relevant instruction set is not supported. For this purpose, following new defines are provided if instruction set is supported: - HAVE_SSE, - HAVE_SSE2, - HAVE_SSE3, - HAVE_SSSE3, - HAVE_SSE4_1, - HAVE_SSE4_2, - HAVE_AVX, - HAVE_AVX2. For detecting if an instruction set can be used in runtime, following functions are provided in (include/linux/simd_x86.h): - zfs_sse_available() - zfs_sse2_available() - zfs_sse3_available() - zfs_ssse3_available() - zfs_sse4_1_available() - zfs_sse4_2_available() - zfs_avx_available() - zfs_avx2_available() - zfs_bmi1_available() - zfs_bmi2_available() These function should be called once, on module load, or initialization. They are safe to use from user and kernel space. If an implementation is using more than single instruction set, both compiler and runtime support for all relevant instruction sets should be checked. Kernel fpu methods: - kfpu_begin() - kfpu_end() Use __get_cpuid_max and __cpuid_count from <cpuid.h> Both gcc and clang have support for these. They also handle ebx register in case it is used for PIC code. Signed-off-by: Gvozden Neskovic <neskovic@gmail.com> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Chunwei Chen <tuxoko@gmail.com> Closes #4381
2016-02-29 21:42:27 +03:00
],[
kernel_fpu fixes This patch fixes a few issues when detecting which kernel_fpu functions are available. - Use kernel_fpu_begin() if it's exported on newer kernels. - Use ZFS_LINUX_TRY_COMPILE_SYMBOL() to choose the right kernel_fpu function when using --enable-linux-builtin. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259 Closes #8363
2019-03-07 03:03:03 +03:00
ZFS_LINUX_TRY_COMPILE_SYMBOL([
#include <linux/module.h>
#ifdef HAVE_KERNEL_FPU_API_HEADER
Linux 5.0 compat: Disable vector instructions on 5.0+ kernels The 5.0 kernel no longer exports the functions we need to do vector (SSE/SSE2/SSE3/AVX...) instructions. Disable vector-based checksum algorithms when building against those kernels. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259
2019-01-12 05:01:28 +03:00
#include <asm/fpu/api.h>
kernel_fpu fixes This patch fixes a few issues when detecting which kernel_fpu functions are available. - Use kernel_fpu_begin() if it's exported on newer kernels. - Use ZFS_LINUX_TRY_COMPILE_SYMBOL() to choose the right kernel_fpu function when using --enable-linux-builtin. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259 Closes #8363
2019-03-07 03:03:03 +03:00
#else
#include <asm/i387.h>
#include <asm/xcr.h>
#endif
MODULE_LICENSE("$ZFS_META_LICENSE");
Linux 5.0 compat: Disable vector instructions on 5.0+ kernels The 5.0 kernel no longer exports the functions we need to do vector (SSE/SSE2/SSE3/AVX...) instructions. Disable vector-based checksum algorithms when building against those kernels. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259
2019-01-12 05:01:28 +03:00
],[
__kernel_fpu_begin();
__kernel_fpu_end();
kernel_fpu fixes This patch fixes a few issues when detecting which kernel_fpu functions are available. - Use kernel_fpu_begin() if it's exported on newer kernels. - Use ZFS_LINUX_TRY_COMPILE_SYMBOL() to choose the right kernel_fpu function when using --enable-linux-builtin. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259 Closes #8363
2019-03-07 03:03:03 +03:00
], [__kernel_fpu_begin], [arch/x86/kernel/fpu/core.c arch/x86/kernel/i387.c], [
Linux 5.0 compat: Disable vector instructions on 5.0+ kernels The 5.0 kernel no longer exports the functions we need to do vector (SSE/SSE2/SSE3/AVX...) instructions. Disable vector-based checksum algorithms when building against those kernels. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259
2019-01-12 05:01:28 +03:00
AC_MSG_RESULT(__kernel_fpu_*)
Linux 5.0 compat: SIMD compatibility Restore the SIMD optimization for 4.19.38 LTS, 4.14.120 LTS, and 5.0 and newer kernels. This is accomplished by leveraging the fact that by definition dedicated kernel threads never need to concern themselves with saving and restoring the user FPU state. Therefore, they may use the FPU as long as we can guarantee user tasks always restore their FPU state before context switching back to user space. For the 5.0 and 5.1 kernels disabling preemption and local interrupts is sufficient to allow the FPU to be used. All non-kernel threads will restore the preserved user FPU state. For 5.2 and latter kernels the user FPU state restoration will be skipped if the kernel determines the registers have not changed. Therefore, for these kernels we need to perform the additional step of saving and restoring the FPU registers. Invalidating the per-cpu global tracking the FPU state would force a restore but that functionality is private to the core x86 FPU implementation and unavailable. In practice, restricting SIMD to kernel threads is not a major restriction for ZFS. The vast majority of SIMD operations are already performed by the IO pipeline. The remaining cases are relatively infrequent and can be handled by the generic code without significant impact. The two most noteworthy cases are: 1) Decrypting the wrapping key for an encrypted dataset, i.e. `zfs load-key`. All other encryption and decryption operations will use the SIMD optimized implementations. 2) Generating the payload checksums for a `zfs send` stream. In order to avoid making any changes to the higher layers of ZFS all of the `*_get_ops()` functions were updated to take in to consideration the calling context. This allows for the fastest implementation to be used as appropriate (see kfpu_allowed()). The only other notable instance of SIMD operations being used outside a kernel thread was at module load time. This code was moved in to a taskq in order to accommodate the new kernel thread restriction. Finally, a few other modifications were made in order to further harden this code and facilitate testing. They include updating each implementations operations structure to be declared as a constant. And allowing "cycle" to be set when selecting the preferred ops in the kernel as well as user space. Reviewed-by: Tony Hutter <hutter2@llnl.gov> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #8754 Closes #8793 Closes #8965
2019-07-12 19:31:20 +03:00
AC_DEFINE(HAVE_UNDERSCORE_KERNEL_FPU, 1,
[kernel has __kernel_fpu_* functions])
AC_DEFINE(KERNEL_EXPORTS_X86_FPU, 1,
[kernel exports FPU functions])
Linux 5.0 compat: Disable vector instructions on 5.0+ kernels The 5.0 kernel no longer exports the functions we need to do vector (SSE/SSE2/SSE3/AVX...) instructions. Disable vector-based checksum algorithms when building against those kernels. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259
2019-01-12 05:01:28 +03:00
],[
Linux 5.0 compat: SIMD compatibility Restore the SIMD optimization for 4.19.38 LTS, 4.14.120 LTS, and 5.0 and newer kernels. This is accomplished by leveraging the fact that by definition dedicated kernel threads never need to concern themselves with saving and restoring the user FPU state. Therefore, they may use the FPU as long as we can guarantee user tasks always restore their FPU state before context switching back to user space. For the 5.0 and 5.1 kernels disabling preemption and local interrupts is sufficient to allow the FPU to be used. All non-kernel threads will restore the preserved user FPU state. For 5.2 and latter kernels the user FPU state restoration will be skipped if the kernel determines the registers have not changed. Therefore, for these kernels we need to perform the additional step of saving and restoring the FPU registers. Invalidating the per-cpu global tracking the FPU state would force a restore but that functionality is private to the core x86 FPU implementation and unavailable. In practice, restricting SIMD to kernel threads is not a major restriction for ZFS. The vast majority of SIMD operations are already performed by the IO pipeline. The remaining cases are relatively infrequent and can be handled by the generic code without significant impact. The two most noteworthy cases are: 1) Decrypting the wrapping key for an encrypted dataset, i.e. `zfs load-key`. All other encryption and decryption operations will use the SIMD optimized implementations. 2) Generating the payload checksums for a `zfs send` stream. In order to avoid making any changes to the higher layers of ZFS all of the `*_get_ops()` functions were updated to take in to consideration the calling context. This allows for the fastest implementation to be used as appropriate (see kfpu_allowed()). The only other notable instance of SIMD operations being used outside a kernel thread was at module load time. This code was moved in to a taskq in order to accommodate the new kernel thread restriction. Finally, a few other modifications were made in order to further harden this code and facilitate testing. They include updating each implementations operations structure to be declared as a constant. And allowing "cycle" to be set when selecting the preferred ops in the kernel as well as user space. Reviewed-by: Tony Hutter <hutter2@llnl.gov> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #8754 Closes #8793 Closes #8965
2019-07-12 19:31:20 +03:00
ZFS_LINUX_TRY_COMPILE([
#include <linux/module.h>
#include <linux/sched.h>
],[
struct fpu *fpu = &current->thread.fpu;
if (fpu->initialized) { return (0); };
],[
AC_MSG_RESULT(fpu.initialized)
AC_DEFINE(HAVE_KERNEL_FPU_INITIALIZED, 1,
[kernel fpu.initialized exists])
],[
ZFS_LINUX_TRY_COMPILE([
#include <linux/module.h>
#include <asm/thread_info.h>
#if !defined(TIF_NEED_FPU_LOAD)
#error "TIF_NEED_FPU_LOAD undefined"
#endif
],[
],[
AC_MSG_RESULT(TIF_NEED_FPU_LOAD)
AC_DEFINE(
HAVE_KERNEL_TIF_NEED_FPU_LOAD, 1,
[kernel TIF_NEED_FPU_LOAD exists])
],[
AC_MSG_RESULT(unavailable)
])
])
Linux 5.0 compat: Disable vector instructions on 5.0+ kernels The 5.0 kernel no longer exports the functions we need to do vector (SSE/SSE2/SSE3/AVX...) instructions. Disable vector-based checksum algorithms when building against those kernels. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes #8259
2019-01-12 05:01:28 +03:00
])
Support for vectorized algorithms on x86 This is initial support for x86 vectorized implementations of ZFS parity and checksum algorithms. For the compilation phase, configure step checks if toolchain supports relevant instruction sets. Each implementation must ensure that the code is not passed to compiler if relevant instruction set is not supported. For this purpose, following new defines are provided if instruction set is supported: - HAVE_SSE, - HAVE_SSE2, - HAVE_SSE3, - HAVE_SSSE3, - HAVE_SSE4_1, - HAVE_SSE4_2, - HAVE_AVX, - HAVE_AVX2. For detecting if an instruction set can be used in runtime, following functions are provided in (include/linux/simd_x86.h): - zfs_sse_available() - zfs_sse2_available() - zfs_sse3_available() - zfs_ssse3_available() - zfs_sse4_1_available() - zfs_sse4_2_available() - zfs_avx_available() - zfs_avx2_available() - zfs_bmi1_available() - zfs_bmi2_available() These function should be called once, on module load, or initialization. They are safe to use from user and kernel space. If an implementation is using more than single instruction set, both compiler and runtime support for all relevant instruction sets should be checked. Kernel fpu methods: - kfpu_begin() - kfpu_end() Use __get_cpuid_max and __cpuid_count from <cpuid.h> Both gcc and clang have support for these. They also handle ebx register in case it is used for PIC code. Signed-off-by: Gvozden Neskovic <neskovic@gmail.com> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Chunwei Chen <tuxoko@gmail.com> Closes #4381
2016-02-29 21:42:27 +03:00
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