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| Started by | Ingo Molnar <mingo@kernel.org> |
|---|---|
| First post | 2017-09-28 10:10 +0200 |
| Last post | 2017-09-28 11:50 +0200 |
| Articles | 3 — 2 participants |
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Re: [PATCHv7 01/19] mm/sparsemem: Allocate mem_section at runtime for SPARSEMEM_EXTREME Ingo Molnar <mingo@kernel.org> - 2017-09-28 10:10 +0200
Re: [PATCHv7 01/19] mm/sparsemem: Allocate mem_section at runtime for SPARSEMEM_EXTREME "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-09-28 11:10 +0200
Re: [PATCHv7 01/19] mm/sparsemem: Allocate mem_section at runtime for SPARSEMEM_EXTREME Ingo Molnar <mingo@kernel.org> - 2017-09-28 11:50 +0200
| From | Ingo Molnar <mingo@kernel.org> |
|---|---|
| Date | 2017-09-28 10:10 +0200 |
| Subject | Re: [PATCHv7 01/19] mm/sparsemem: Allocate mem_section at runtime for SPARSEMEM_EXTREME |
| Message-ID | <uuC3o-6tW-3@gated-at.bofh.it> |
* Kirill A. Shutemov <kirill.shutemov@linux.intel.com> wrote: > Size of mem_section array depends on size of physical address space. > > In preparation for boot-time switching between paging modes on x86-64 > we need to make allocation of mem_section dynamic. > > The patch allocates the array on the first call to > sparse_memory_present_with_active_regions(). > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> What is the size of the allocations here, in bytes, for the two main variants? Thanks, Ingo
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| From | "Kirill A. Shutemov" <kirill@shutemov.name> |
|---|---|
| Date | 2017-09-28 11:10 +0200 |
| Message-ID | <uuCZs-743-11@gated-at.bofh.it> |
| In reply to | #1741254 |
On Thu, Sep 28, 2017 at 10:07:11AM +0200, Ingo Molnar wrote: > > * Kirill A. Shutemov <kirill.shutemov@linux.intel.com> wrote: > > > Size of mem_section array depends on size of physical address space. > > > > In preparation for boot-time switching between paging modes on x86-64 > > we need to make allocation of mem_section dynamic. > > > > The patch allocates the array on the first call to > > sparse_memory_present_with_active_regions(). > > > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > > What is the size of the allocations here, in bytes, for the two main variants? For 4-level paging it's 32k. For 5-level paging it's 2M. -- Kirill A. Shutemov
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| From | Ingo Molnar <mingo@kernel.org> |
|---|---|
| Date | 2017-09-28 11:50 +0200 |
| Message-ID | <uuDCa-7kq-23@gated-at.bofh.it> |
| In reply to | #1741307 |
* Kirill A. Shutemov <kirill@shutemov.name> wrote: > On Thu, Sep 28, 2017 at 10:07:11AM +0200, Ingo Molnar wrote: > > > > * Kirill A. Shutemov <kirill.shutemov@linux.intel.com> wrote: > > > > > Size of mem_section array depends on size of physical address space. > > > > > > In preparation for boot-time switching between paging modes on x86-64 > > > we need to make allocation of mem_section dynamic. > > > > > > The patch allocates the array on the first call to > > > sparse_memory_present_with_active_regions(). > > > > > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > > > > What is the size of the allocations here, in bytes, for the two main variants? > > For 4-level paging it's 32k. For 5-level paging it's 2M. Ok, please put this information into the changelog, because it's relevant: we don't want to waste 2MB of RAM on the majority of systems that boot a distro kernel with 5-level paging enabled. Thanks, Ingo
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