Re: [PATCH v1 2/4] memblock: update initialization of reserved pages
On Tue, Apr 20, 2021 at 05:18:55PM +0200, David Hildenbrand wrote: > On 20.04.21 17:03, Mike Rapoport wrote: > > On Tue, Apr 20, 2021 at 03:56:28PM +0200, David Hildenbrand wrote: > > > On 20.04.21 11:09, Mike Rapoport wrote: > > > > From: Mike Rapoport > > > > > > > > The struct pages representing a reserved memory region are initialized > > > > using reserve_bootmem_range() function. This function is called for each > > > > reserved region just before the memory is freed from memblock to the > > > > buddy > > > > page allocator. > > > > > > > > The struct pages for MEMBLOCK_NOMAP regions are kept with the default > > > > values set by the memory map initialization which makes it necessary to > > > > have a special treatment for such pages in pfn_valid() and > > > > pfn_valid_within(). > > > > > > Just a general question while thinking about it: > > > > > > Would we right now initialize the memmap of these pages already via > > > memmap_init_zone()->memmap_init_range()? (IOW, not marking the > > > PageReserved?) > > > > Yep. These pages are part of memblock.memory so they are initialized in > > memmap_init_zone()->memmap_init_range() to the default values. > > > > So instead of fully initializing them again, we mostly would only have to > set PageReserved(). Not sure how big that memory usually is -- IOW, if we > really care about optimizing the double-init. IIUC, these are small areas reserved by the firmware, like e.g. ACPI tables. @Ard, am I right? -- Sincerely yours, Mike.
Re: [PATCH v1 2/4] memblock: update initialization of reserved pages
On 20.04.21 17:03, Mike Rapoport wrote: On Tue, Apr 20, 2021 at 03:56:28PM +0200, David Hildenbrand wrote: On 20.04.21 11:09, Mike Rapoport wrote: From: Mike Rapoport The struct pages representing a reserved memory region are initialized using reserve_bootmem_range() function. This function is called for each reserved region just before the memory is freed from memblock to the buddy page allocator. The struct pages for MEMBLOCK_NOMAP regions are kept with the default values set by the memory map initialization which makes it necessary to have a special treatment for such pages in pfn_valid() and pfn_valid_within(). Just a general question while thinking about it: Would we right now initialize the memmap of these pages already via memmap_init_zone()->memmap_init_range()? (IOW, not marking the PageReserved?) Yep. These pages are part of memblock.memory so they are initialized in memmap_init_zone()->memmap_init_range() to the default values. So instead of fully initializing them again, we mostly would only have to set PageReserved(). Not sure how big that memory usually is -- IOW, if we really care about optimizing the double-init. -- Thanks, David / dhildenb
Re: [PATCH v1 2/4] memblock: update initialization of reserved pages
On Tue, Apr 20, 2021 at 03:56:28PM +0200, David Hildenbrand wrote: > On 20.04.21 11:09, Mike Rapoport wrote: > > From: Mike Rapoport > > > > The struct pages representing a reserved memory region are initialized > > using reserve_bootmem_range() function. This function is called for each > > reserved region just before the memory is freed from memblock to the buddy > > page allocator. > > > > The struct pages for MEMBLOCK_NOMAP regions are kept with the default > > values set by the memory map initialization which makes it necessary to > > have a special treatment for such pages in pfn_valid() and > > pfn_valid_within(). > > Just a general question while thinking about it: > > Would we right now initialize the memmap of these pages already via > memmap_init_zone()->memmap_init_range()? (IOW, not marking the > PageReserved?) Yep. These pages are part of memblock.memory so they are initialized in memmap_init_zone()->memmap_init_range() to the default values. -- Sincerely yours, Mike.
Re: [PATCH v1 2/4] memblock: update initialization of reserved pages
On 20.04.21 11:09, Mike Rapoport wrote: From: Mike Rapoport The struct pages representing a reserved memory region are initialized using reserve_bootmem_range() function. This function is called for each reserved region just before the memory is freed from memblock to the buddy page allocator. The struct pages for MEMBLOCK_NOMAP regions are kept with the default values set by the memory map initialization which makes it necessary to have a special treatment for such pages in pfn_valid() and pfn_valid_within(). Just a general question while thinking about it: Would we right now initialize the memmap of these pages already via memmap_init_zone()->memmap_init_range()? (IOW, not marking the PageReserved?) -- Thanks, David / dhildenb
