| Message ID | 20230323105243.2807166-1-chaitanyas.prakash@arm.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | selftests/mm: Implement support for arm64 on va | expand |
On Thu, Mar 23, 2023 at 04:22:38PM +0530, Chaitanya S Prakash wrote: > The va_128TBswitch selftest is designed and implemented for PowerPC and > x86 architectures which support a 128TB switch, up to 256TB of virtual > address space and hugepage sizes of 16MB and 2MB respectively. Arm64 > platforms on the other hand support a 256Tb switch, up to 4PB of virtual > address space and a default hugepage size of 512MB when 64k pagesize is > enabled. > > These architectural differences require introducing support for arm64 > platforms, after which a more generic naming convention is suggested. > The in code comments are amended to provide a more platform independent > explanation of the working of the code and nr_hugepages are configured > as required. Finally, the file running the testcase is modified in order > to prevent skipping of hugetlb testcases of va_high_addr_switch. > > This series has been tested on 6.3.0-rc3 kernel, both on arm64 and x86 > platforms. > > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> > Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > Cc: Shuah Khan <shuah@kernel.org> > Cc: linux-mm@kvack.org > Cc: linux-kselftest@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > > Chaitanya S Prakash (5): > selftests/mm: Add support for arm64 platform on va switch > selftests/mm: Rename va_128TBswitch to va_high_addr_switch > selftests/mm: Add platform independent in code comments > selftests/mm: Configure nr_hugepages for arm64 > selftests/mm: Run hugetlb testcases of va switch > > tools/testing/selftests/mm/Makefile | 4 +- > tools/testing/selftests/mm/run_vmtests.sh | 12 +++++- > ...va_128TBswitch.c => va_high_addr_switch.c} | 41 +++++++++++++++---- > ..._128TBswitch.sh => va_high_addr_switch.sh} | 6 ++- > 4 files changed, 49 insertions(+), 14 deletions(-) > rename tools/testing/selftests/mm/{va_128TBswitch.c => va_high_addr_switch.c} (86%) > rename tools/testing/selftests/mm/{va_128TBswitch.sh => va_high_addr_switch.sh} (89%) The patchset looks sane to me, but I have question: why arm64 has switch on 256TB. The reason we have the switch is to keep system backward compatible. Maybe it is better to make arm64 switch also on 128TB to make it compatible across architectures?
On Thu, Mar 23, 2023 at 02:14:36PM +0300, Kirill A. Shutemov wrote: > On Thu, Mar 23, 2023 at 04:22:38PM +0530, Chaitanya S Prakash wrote: > > The va_128TBswitch selftest is designed and implemented for PowerPC and > > x86 architectures which support a 128TB switch, up to 256TB of virtual > > address space and hugepage sizes of 16MB and 2MB respectively. Arm64 > > platforms on the other hand support a 256Tb switch, up to 4PB of virtual > > address space and a default hugepage size of 512MB when 64k pagesize is > > enabled. > > > > These architectural differences require introducing support for arm64 > > platforms, after which a more generic naming convention is suggested. > > The in code comments are amended to provide a more platform independent > > explanation of the working of the code and nr_hugepages are configured > > as required. Finally, the file running the testcase is modified in order > > to prevent skipping of hugetlb testcases of va_high_addr_switch. > > > > This series has been tested on 6.3.0-rc3 kernel, both on arm64 and x86 > > platforms. > > > > Cc: Andrew Morton <akpm@linux-foundation.org> > > Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> > > Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > > Cc: Shuah Khan <shuah@kernel.org> > > Cc: linux-mm@kvack.org > > Cc: linux-kselftest@vger.kernel.org > > Cc: linux-kernel@vger.kernel.org > > > > Chaitanya S Prakash (5): > > selftests/mm: Add support for arm64 platform on va switch > > selftests/mm: Rename va_128TBswitch to va_high_addr_switch > > selftests/mm: Add platform independent in code comments > > selftests/mm: Configure nr_hugepages for arm64 > > selftests/mm: Run hugetlb testcases of va switch > > > > tools/testing/selftests/mm/Makefile | 4 +- > > tools/testing/selftests/mm/run_vmtests.sh | 12 +++++- > > ...va_128TBswitch.c => va_high_addr_switch.c} | 41 +++++++++++++++---- > > ..._128TBswitch.sh => va_high_addr_switch.sh} | 6 ++- > > 4 files changed, 49 insertions(+), 14 deletions(-) > > rename tools/testing/selftests/mm/{va_128TBswitch.c => va_high_addr_switch.c} (86%) > > rename tools/testing/selftests/mm/{va_128TBswitch.sh => va_high_addr_switch.sh} (89%) > > The patchset looks sane to me, but I have question: why arm64 has switch > on 256TB. The reason we have the switch is to keep system backward > compatible. It's the same reason, it's just that arm64 initially supported 48-bits / 256TB of user addresses (0x0000000000000000..0x0000ffffffffffff), while x86_64 supported 47-bits / 128TB (0x0000000000000000..0x00007fffffffffff). Note: arm64 has separate page tables for the user / kernel halves of the VA space, which in practice means we get an extra bit of address range for each half. > Maybe it is better to make arm64 switch also on 128TB to make it > compatible across architectures? I don't think that's something that we can change; user addresses between 128TB and 256TB have been the case for over a decade now, and avoiding that by default could easily break something. Thanks, Mark.
On Thu, 23 Mar 2023 16:22:38 +0530 Chaitanya S Prakash <chaitanyas.prakash@arm.com> wrote: > The va_128TBswitch selftest is designed and implemented for PowerPC and > x86 architectures which support a 128TB switch, up to 256TB of virtual > address space and hugepage sizes of 16MB and 2MB respectively. Arm64 > platforms on the other hand support a 256Tb switch, up to 4PB of virtual > address space and a default hugepage size of 512MB when 64k pagesize is > enabled. > > These architectural differences require introducing support for arm64 > platforms, after which a more generic naming convention is suggested. > The in code comments are amended to provide a more platform independent > explanation of the working of the code and nr_hugepages are configured > as required. Finally, the file running the testcase is modified in order > to prevent skipping of hugetlb testcases of va_high_addr_switch. > > This series has been tested on 6.3.0-rc3 kernel, both on arm64 and x86 > platforms. Would it make sense to get this series into the ARM tree, so it sees more testing on ARM?
On 3/24/23 03:19, Andrew Morton wrote: > On Thu, 23 Mar 2023 16:22:38 +0530 Chaitanya S Prakash <chaitanyas.prakash@arm.com> wrote: > >> The va_128TBswitch selftest is designed and implemented for PowerPC and >> x86 architectures which support a 128TB switch, up to 256TB of virtual >> address space and hugepage sizes of 16MB and 2MB respectively. Arm64 >> platforms on the other hand support a 256Tb switch, up to 4PB of virtual >> address space and a default hugepage size of 512MB when 64k pagesize is >> enabled. >> >> These architectural differences require introducing support for arm64 >> platforms, after which a more generic naming convention is suggested. >> The in code comments are amended to provide a more platform independent >> explanation of the working of the code and nr_hugepages are configured >> as required. Finally, the file running the testcase is modified in order >> to prevent skipping of hugetlb testcases of va_high_addr_switch. >> >> This series has been tested on 6.3.0-rc3 kernel, both on arm64 and x86 >> platforms. > > Would it make sense to get this series into the ARM tree, so it sees > more testing on ARM Rather, it will be better for this series to go via the mm tree instead (via linux-next first) for better coverage on all platforms, this being a common test.
On 3/23/23 16:22, Chaitanya S Prakash wrote: > The va_128TBswitch selftest is designed and implemented for PowerPC and > x86 architectures which support a 128TB switch, up to 256TB of virtual > address space and hugepage sizes of 16MB and 2MB respectively. Arm64 > platforms on the other hand support a 256Tb switch, up to 4PB of virtual > address space and a default hugepage size of 512MB when 64k pagesize is > enabled. > > These architectural differences require introducing support for arm64 > platforms, after which a more generic naming convention is suggested. > The in code comments are amended to provide a more platform independent > explanation of the working of the code and nr_hugepages are configured > as required. Finally, the file running the testcase is modified in order > to prevent skipping of hugetlb testcases of va_high_addr_switch. > > This series has been tested on 6.3.0-rc3 kernel, both on arm64 and x86 > platforms. Gentle ping, any updates? > > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> > Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > Cc: Shuah Khan <shuah@kernel.org> > Cc: linux-mm@kvack.org > Cc: linux-kselftest@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > > Chaitanya S Prakash (5): > selftests/mm: Add support for arm64 platform on va switch > selftests/mm: Rename va_128TBswitch to va_high_addr_switch > selftests/mm: Add platform independent in code comments > selftests/mm: Configure nr_hugepages for arm64 > selftests/mm: Run hugetlb testcases of va switch > > tools/testing/selftests/mm/Makefile | 4 +- > tools/testing/selftests/mm/run_vmtests.sh | 12 +++++- > ...va_128TBswitch.c => va_high_addr_switch.c} | 41 +++++++++++++++---- > ..._128TBswitch.sh => va_high_addr_switch.sh} | 6 ++- > 4 files changed, 49 insertions(+), 14 deletions(-) > rename tools/testing/selftests/mm/{va_128TBswitch.c => va_high_addr_switch.c} (86%) > rename tools/testing/selftests/mm/{va_128TBswitch.sh => va_high_addr_switch.sh} (89%) >
The va_128TBswitch selftest is designed and implemented for PowerPC and x86 architectures which support a 128TB switch, up to 256TB of virtual address space and hugepage sizes of 16MB and 2MB respectively. Arm64 platforms on the other hand support a 256Tb switch, up to 4PB of virtual address space and a default hugepage size of 512MB when 64k pagesize is enabled. These architectural differences require introducing support for arm64 platforms, after which a more generic naming convention is suggested. The in code comments are amended to provide a more platform independent explanation of the working of the code and nr_hugepages are configured as required. Finally, the file running the testcase is modified in order to prevent skipping of hugetlb testcases of va_high_addr_switch. This series has been tested on 6.3.0-rc3 kernel, both on arm64 and x86 platforms. Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: linux-mm@kvack.org Cc: linux-kselftest@vger.kernel.org Cc: linux-kernel@vger.kernel.org Chaitanya S Prakash (5): selftests/mm: Add support for arm64 platform on va switch selftests/mm: Rename va_128TBswitch to va_high_addr_switch selftests/mm: Add platform independent in code comments selftests/mm: Configure nr_hugepages for arm64 selftests/mm: Run hugetlb testcases of va switch tools/testing/selftests/mm/Makefile | 4 +- tools/testing/selftests/mm/run_vmtests.sh | 12 +++++- ...va_128TBswitch.c => va_high_addr_switch.c} | 41 +++++++++++++++---- ..._128TBswitch.sh => va_high_addr_switch.sh} | 6 ++- 4 files changed, 49 insertions(+), 14 deletions(-) rename tools/testing/selftests/mm/{va_128TBswitch.c => va_high_addr_switch.c} (86%) rename tools/testing/selftests/mm/{va_128TBswitch.sh => va_high_addr_switch.sh} (89%)