Re: [PATCH v2 00/13] arch, mm: deprecate DISCONTIGMEM
Hi! On 11/1/20 6:04 PM, Mike Rapoport wrote: > It's been a while since DISCONTIGMEM is generally considered deprecated, > but it is still used by four architectures. This set replaces DISCONTIGMEM > with a different way to handle holes in the memory map and marks > DISCONTIGMEM configuration as BROKEN in Kconfigs of these architectures with > the intention to completely remove it in several releases. > > While for 64-bit alpha and ia64 the switch to SPARSEMEM is quite obvious > and was a matter of moving some bits around, for smaller 32-bit arc and > m68k SPARSEMEM is not necessarily the best thing to do. > > On 32-bit machines SPARSEMEM would require large sections to make section > index fit in the page flags, but larger sections mean that more memory is > wasted for unused memory map. > > Besides, pfn_to_page() and page_to_pfn() become less efficient, at least on > arc. > > So I've decided to generalize arm's approach for freeing of unused parts of > the memory map with FLATMEM and enable it for both arc and m68k. The > details are in the description of patches 10 (arc) and 13 (m68k). Apologies for the late reply. Is this still relevant for testing? I have already successfully tested v1 of the patch set, shall I test v2? Adrian -- .''`. John Paul Adrian Glaubitz : :' : Debian Developer - glaub...@debian.org `. `' Freie Universitaet Berlin - glaub...@physik.fu-berlin.de `-GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913 ___ linux-snps-arc mailing list linux-snps-arc@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-snps-arc
Re: [PATCH v2 00/13] arch, mm: deprecate DISCONTIGMEM
Hi Adrian, On Tue, Nov 17, 2020 at 06:24:51AM +0100, John Paul Adrian Glaubitz wrote: > Hi! > > On 11/1/20 6:04 PM, Mike Rapoport wrote: > > It's been a while since DISCONTIGMEM is generally considered deprecated, > > but it is still used by four architectures. This set replaces DISCONTIGMEM > > with a different way to handle holes in the memory map and marks > > DISCONTIGMEM configuration as BROKEN in Kconfigs of these architectures with > > the intention to completely remove it in several releases. > > > > While for 64-bit alpha and ia64 the switch to SPARSEMEM is quite obvious > > and was a matter of moving some bits around, for smaller 32-bit arc and > > m68k SPARSEMEM is not necessarily the best thing to do. > > > > On 32-bit machines SPARSEMEM would require large sections to make section > > index fit in the page flags, but larger sections mean that more memory is > > wasted for unused memory map. > > > > Besides, pfn_to_page() and page_to_pfn() become less efficient, at least on > > arc. > > > > So I've decided to generalize arm's approach for freeing of unused parts of > > the memory map with FLATMEM and enable it for both arc and m68k. The > > details are in the description of patches 10 (arc) and 13 (m68k). > > Apologies for the late reply. Is this still relevant for testing? > > I have already successfully tested v1 of the patch set, shall I test v2? There were minor differences only for m68k between the versions. I've verified them on ARAnyM but if you have a real machine a run there would be nice. > Adrian > > -- > .''`. John Paul Adrian Glaubitz > : :' : Debian Developer - glaub...@debian.org > `. `' Freie Universitaet Berlin - glaub...@physik.fu-berlin.de > `-GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913 > > -- Sincerely yours, Mike. ___ linux-snps-arc mailing list linux-snps-arc@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-snps-arc
Re: [PATCH v2 10/13] arc: use FLATMEM with freeing of unused memory map instead of DISCONTIGMEM
Hi Mike, On 11/1/20 9:04 AM, Mike Rapoport wrote: > From: Mike Rapoport > > Currently ARC uses DISCONTIGMEM to cope with sparse physical memory address > space on systems with 2 memory banks. While DISCONTIGMEM avoids wasting > memory on unpopulated memory map, it adds both memory and CPU overhead > relatively to FLATMEM. Moreover, DISCONTINGMEM is generally considered > deprecated. > > The obvious replacement for DISCONTIGMEM would be SPARSEMEM, but it is also > less efficient than FLATMEM in pfn_to_page() and page_to_pfn() conversions. > Besides it requires tuning of SECTION_SIZE which is not trivial for > possible ARC memory configuration. > > Since the memory map for both banks is always allocated from the "lowmem" > bank, it is possible to use FLATMEM for two-bank configuration and simply > free the unused hole in the memory map. All is required for that is to > provide ARC-specific pfn_valid() that will take into account actual > physical memory configuration and define HAVE_ARCH_PFN_VALID. > > The resulting kernel image configured with defconfig + HIGHMEM=y is > smaller: > > $ size a/vmlinux b/vmlinux > textdata bss dec hex filename > 4673503 1245456 279756 6198715 5e95bb a/vmlinux > 4658706 1246864 279756 6185326 5e616e b/vmlinux > > $ ./scripts/bloat-o-meter a/vmlinux b/vmlinux > add/remove: 28/30 grow/shrink: 42/399 up/down: 10986/-29025 (-18039) > ... > Total: Before=4709315, After=4691276, chg -0.38% > > Booting nSIM with haps_ns.dts results in the following memory usage > reports: > > a: > Memory: 1559104K/1572864K available (3531K kernel code, 595K rwdata, 752K > rodata, 136K init, 275K bss, 13760K reserved, 0K cma-reserved, 1048576K > highmem) > > b: > Memory: 1559112K/1572864K available (3519K kernel code, 594K rwdata, 752K > rodata, 136K init, 280K bss, 13752K reserved, 0K cma-reserved, 1048576K > highmem) > > Signed-off-by: Mike Rapoport Sorry this fell through the cracks. Do you have a branch I can checkout and do a quick test. Thx, -Vineet > --- > arch/arc/Kconfig| 3 ++- > arch/arc/include/asm/page.h | 20 +--- > arch/arc/mm/init.c | 29 ++--- > 3 files changed, 41 insertions(+), 11 deletions(-) > > diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig > index 0a89cc9def65..c874f8ab0341 100644 > --- a/arch/arc/Kconfig > +++ b/arch/arc/Kconfig > @@ -67,6 +67,7 @@ config GENERIC_CSUM > > config ARCH_DISCONTIGMEM_ENABLE > def_bool n > + depends on BROKEN > > config ARCH_FLATMEM_ENABLE > def_bool y > @@ -506,7 +507,7 @@ config LINUX_RAM_BASE > > config HIGHMEM > bool "High Memory Support" > - select ARCH_DISCONTIGMEM_ENABLE > + select HAVE_ARCH_PFN_VALID > help > With ARC 2G:2G address split, only upper 2G is directly addressable by > kernel. Enable this to potentially allow access to rest of 2G and PAE > diff --git a/arch/arc/include/asm/page.h b/arch/arc/include/asm/page.h > index b0dfed0f12be..23e41e890eda 100644 > --- a/arch/arc/include/asm/page.h > +++ b/arch/arc/include/asm/page.h > @@ -82,11 +82,25 @@ typedef pte_t * pgtable_t; >*/ > #define virt_to_pfn(kaddr) (__pa(kaddr) >> PAGE_SHIFT) > > -#define ARCH_PFN_OFFSET virt_to_pfn(CONFIG_LINUX_RAM_BASE) > +/* > + * When HIGHMEM is enabled we have holes in the memory map so we need > + * pfn_valid() that takes into account the actual extents of the physical > + * memory > + */ > +#ifdef CONFIG_HIGHMEM > + > +extern unsigned long arch_pfn_offset; > +#define ARCH_PFN_OFFSET arch_pfn_offset > + > +extern int pfn_valid(unsigned long pfn); > +#define pfn_validpfn_valid > > -#ifdef CONFIG_FLATMEM > +#else /* CONFIG_HIGHMEM */ > + > +#define ARCH_PFN_OFFSET virt_to_pfn(CONFIG_LINUX_RAM_BASE) > #define pfn_valid(pfn) (((pfn) - ARCH_PFN_OFFSET) < max_mapnr) > -#endif > + > +#endif /* CONFIG_HIGHMEM */ > > /* >* __pa, __va, virt_to_page (ALERT: deprecated, don't use them) > diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c > index 3a35b82a718e..ce07e697916c 100644 > --- a/arch/arc/mm/init.c > +++ b/arch/arc/mm/init.c > @@ -28,6 +28,8 @@ static unsigned long low_mem_sz; > static unsigned long min_high_pfn, max_high_pfn; > static phys_addr_t high_mem_start; > static phys_addr_t high_mem_sz; > +unsigned long arch_pfn_offset; > +EXPORT_SYMBOL(arch_pfn_offset); > #endif > > #ifdef CONFIG_DISCONTIGMEM > @@ -98,16 +100,11 @@ void __init setup_arch_memory(void) > init_mm.brk = (unsigned long)_end; > > /* first page of system - kernel .vector starts here */ > - min_low_pfn = ARCH_PFN_OFFSET; > + min_low_pfn = virt_to_pfn(CONFIG_LINUX_RAM_BASE); > > /* Last usable page of low mem */ > max_low_pfn = max_pfn = PFN_DOWN(low_mem_start + low_mem_sz); > > -#ifdef CONFIG_FLATMEM > - /* pfn_valid() uses this */ > - max_mapnr = max_low_pfn - min_low_pfn;
Re: [PATCH v2 10/13] arc: use FLATMEM with freeing of unused memory map instead of DISCONTIGMEM
On Tue, Nov 17, 2020 at 06:40:16AM +, Vineet Gupta wrote: > Hi Mike, > > On 11/1/20 9:04 AM, Mike Rapoport wrote: > > From: Mike Rapoport > > > > Currently ARC uses DISCONTIGMEM to cope with sparse physical memory address > > space on systems with 2 memory banks. While DISCONTIGMEM avoids wasting > > memory on unpopulated memory map, it adds both memory and CPU overhead > > relatively to FLATMEM. Moreover, DISCONTINGMEM is generally considered > > deprecated. > > > > The obvious replacement for DISCONTIGMEM would be SPARSEMEM, but it is also > > less efficient than FLATMEM in pfn_to_page() and page_to_pfn() conversions. > > Besides it requires tuning of SECTION_SIZE which is not trivial for > > possible ARC memory configuration. > > > > Since the memory map for both banks is always allocated from the "lowmem" > > bank, it is possible to use FLATMEM for two-bank configuration and simply > > free the unused hole in the memory map. All is required for that is to > > provide ARC-specific pfn_valid() that will take into account actual > > physical memory configuration and define HAVE_ARCH_PFN_VALID. > > > > The resulting kernel image configured with defconfig + HIGHMEM=y is > > smaller: > > > > $ size a/vmlinux b/vmlinux > > textdata bss dec hex filename > > 4673503 1245456 279756 6198715 5e95bb a/vmlinux > > 4658706 1246864 279756 6185326 5e616e b/vmlinux > > > > $ ./scripts/bloat-o-meter a/vmlinux b/vmlinux > > add/remove: 28/30 grow/shrink: 42/399 up/down: 10986/-29025 (-18039) > > ... > > Total: Before=4709315, After=4691276, chg -0.38% > > > > Booting nSIM with haps_ns.dts results in the following memory usage > > reports: > > > > a: > > Memory: 1559104K/1572864K available (3531K kernel code, 595K rwdata, 752K > > rodata, 136K init, 275K bss, 13760K reserved, 0K cma-reserved, 1048576K > > highmem) > > > > b: > > Memory: 1559112K/1572864K available (3519K kernel code, 594K rwdata, 752K > > rodata, 136K init, 280K bss, 13752K reserved, 0K cma-reserved, 1048576K > > highmem) > > > > Signed-off-by: Mike Rapoport > > Sorry this fell through the cracks. Do you have a branch I can checkout > and do a quick test. It's in mmotm and in my tree: https://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git memory-models/rm-discontig/v0 > Thx, > -Vineet > > > --- > > arch/arc/Kconfig| 3 ++- > > arch/arc/include/asm/page.h | 20 +--- > > arch/arc/mm/init.c | 29 ++--- > > 3 files changed, 41 insertions(+), 11 deletions(-) > > > > diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig > > index 0a89cc9def65..c874f8ab0341 100644 > > --- a/arch/arc/Kconfig > > +++ b/arch/arc/Kconfig > > @@ -67,6 +67,7 @@ config GENERIC_CSUM > > > > config ARCH_DISCONTIGMEM_ENABLE > > def_bool n > > + depends on BROKEN > > > > config ARCH_FLATMEM_ENABLE > > def_bool y > > @@ -506,7 +507,7 @@ config LINUX_RAM_BASE > > > > config HIGHMEM > > bool "High Memory Support" > > - select ARCH_DISCONTIGMEM_ENABLE > > + select HAVE_ARCH_PFN_VALID > > help > > With ARC 2G:2G address split, only upper 2G is directly addressable by > > kernel. Enable this to potentially allow access to rest of 2G and PAE > > diff --git a/arch/arc/include/asm/page.h b/arch/arc/include/asm/page.h > > index b0dfed0f12be..23e41e890eda 100644 > > --- a/arch/arc/include/asm/page.h > > +++ b/arch/arc/include/asm/page.h > > @@ -82,11 +82,25 @@ typedef pte_t * pgtable_t; > >*/ > > #define virt_to_pfn(kaddr)(__pa(kaddr) >> PAGE_SHIFT) > > > > -#define ARCH_PFN_OFFSETvirt_to_pfn(CONFIG_LINUX_RAM_BASE) > > +/* > > + * When HIGHMEM is enabled we have holes in the memory map so we need > > + * pfn_valid() that takes into account the actual extents of the physical > > + * memory > > + */ > > +#ifdef CONFIG_HIGHMEM > > + > > +extern unsigned long arch_pfn_offset; > > +#define ARCH_PFN_OFFSETarch_pfn_offset > > + > > +extern int pfn_valid(unsigned long pfn); > > +#define pfn_valid pfn_valid > > > > -#ifdef CONFIG_FLATMEM > > +#else /* CONFIG_HIGHMEM */ > > + > > +#define ARCH_PFN_OFFSETvirt_to_pfn(CONFIG_LINUX_RAM_BASE) > > #define pfn_valid(pfn)(((pfn) - ARCH_PFN_OFFSET) < max_mapnr) > > -#endif > > + > > +#endif /* CONFIG_HIGHMEM */ > > > > /* > >* __pa, __va, virt_to_page (ALERT: deprecated, don't use them) > > diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c > > index 3a35b82a718e..ce07e697916c 100644 > > --- a/arch/arc/mm/init.c > > +++ b/arch/arc/mm/init.c > > @@ -28,6 +28,8 @@ static unsigned long low_mem_sz; > > static unsigned long min_high_pfn, max_high_pfn; > > static phys_addr_t high_mem_start; > > static phys_addr_t high_mem_sz; > > +unsigned long arch_pfn_offset; > > +EXPORT_SYMBOL(arch_pfn_offset); > > #endif > > > > #ifdef CONFIG_DISCONTIGMEM > > @@ -98,16 +100,11 @@ void __init setup_arch_memory(void) > > init_mm
