Message ID | 1454988763-5580-5-git-send-email-david@gibson.dropbear.id.au (mailing list archive) |
---|---|
State | Accepted |
Headers | show |
David Gibson <david@gibson.dropbear.id.au> writes: > htab_get_table_size() either retrieve the size of the hash page table (HPT) > from the device tree - if the HPT size is determined by firmware - or > uses a heuristic to determine a good size based on RAM size if the kernel > is responsible for allocating the HPT. > > To support a PAPR extension allowing resizing of the HPT, we're going to > want the memory size -> HPT size logic elsewhere, so split it out into a > helper function. > Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au> > --- > arch/powerpc/include/asm/mmu-hash64.h | 3 +++ > arch/powerpc/mm/hash_utils_64.c | 32 +++++++++++++++++++------------- > 2 files changed, 22 insertions(+), 13 deletions(-) > > diff --git a/arch/powerpc/include/asm/mmu-hash64.h b/arch/powerpc/include/asm/mmu-hash64.h > index 7352d3f..cf070fd 100644 > --- a/arch/powerpc/include/asm/mmu-hash64.h > +++ b/arch/powerpc/include/asm/mmu-hash64.h > @@ -607,6 +607,9 @@ static inline unsigned long get_kernel_vsid(unsigned long ea, int ssize) > context = (MAX_USER_CONTEXT) + ((ea >> 60) - 0xc) + 1; > return get_vsid(context, ea, ssize); > } > + > +unsigned htab_shift_for_mem_size(unsigned long mem_size); > + > #endif /* __ASSEMBLY__ */ > > #endif /* _ASM_POWERPC_MMU_HASH64_H_ */ > diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c > index fdcf9d1..da5d279 100644 > --- a/arch/powerpc/mm/hash_utils_64.c > +++ b/arch/powerpc/mm/hash_utils_64.c > @@ -611,10 +611,26 @@ static int __init htab_dt_scan_pftsize(unsigned long node, > return 0; > } > > -static unsigned long __init htab_get_table_size(void) > +unsigned htab_shift_for_mem_size(unsigned long mem_size) > { > - unsigned long mem_size, rnd_mem_size, pteg_count, psize; > + unsigned memshift = __ilog2(mem_size); > + unsigned pshift = mmu_psize_defs[mmu_virtual_psize].shift; > + unsigned pteg_shift; > + > + /* round mem_size up to next power of 2 */ > + if ((1UL << memshift) < mem_size) > + memshift += 1; > + > + /* aim for 2 pages / pteg */ > + pteg_shift = memshift - (pshift + 1); > + > + /* 2^11 PTEGS / 2^18 bytes is the minimum htab size permitted > + * by the architecture */ > + return max(pteg_shift + 7, 18U); > +} > > +static unsigned long __init htab_get_table_size(void) > +{ > /* If hash size isn't already provided by the platform, we try to > * retrieve it from the device-tree. If it's not there neither, we > * calculate it now based on the total RAM size > @@ -624,17 +640,7 @@ static unsigned long __init htab_get_table_size(void) > if (ppc64_pft_size) > return 1UL << ppc64_pft_size; > > - /* round mem_size up to next power of 2 */ > - mem_size = memblock_phys_mem_size(); > - rnd_mem_size = 1UL << __ilog2(mem_size); > - if (rnd_mem_size < mem_size) > - rnd_mem_size <<= 1; > - > - /* # pages / 2 */ > - psize = mmu_psize_defs[mmu_virtual_psize].shift; > - pteg_count = max(rnd_mem_size >> (psize + 1), 1UL << 11); > - > - return pteg_count << 7; > + return 1UL << htab_shift_for_mem_size(memblock_phys_mem_size()); > } > > #ifdef CONFIG_MEMORY_HOTPLUG > -- > 2.5.0
On Tue, 2016-09-02 at 03:32:43 UTC, David Gibson wrote: > htab_get_table_size() either retrieve the size of the hash page table (HPT) > from the device tree - if the HPT size is determined by firmware - or > uses a heuristic to determine a good size based on RAM size if the kernel > is responsible for allocating the HPT. > > To support a PAPR extension allowing resizing of the HPT, we're going to > want the memory size -> HPT size logic elsewhere, so split it out into a > helper function. > > Signed-off-by: David Gibson <david@gibson.dropbear.id.au> > Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/5c3c7ede2bdcb85fa2fd51c814 I reworded one comment a little, from: /* 2^11 PTEGS / 2^18 bytes is the minimum htab size permitted * by the architecture */ to: /* * 2^11 PTEGS of 128 bytes each, ie. 2^18 bytes is the minimum htab * size permitted by the architecture. */ To avoid any confusion about the "/" referring to division. cheers
On Wed, Mar 02, 2016 at 09:21:19AM +1100, Michael Ellerman wrote: > On Tue, 2016-09-02 at 03:32:43 UTC, David Gibson wrote: > > htab_get_table_size() either retrieve the size of the hash page table (HPT) > > from the device tree - if the HPT size is determined by firmware - or > > uses a heuristic to determine a good size based on RAM size if the kernel > > is responsible for allocating the HPT. > > > > To support a PAPR extension allowing resizing of the HPT, we're going to > > want the memory size -> HPT size logic elsewhere, so split it out into a > > helper function. > > > > Signed-off-by: David Gibson <david@gibson.dropbear.id.au> > > Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> > > Applied to powerpc next, thanks. > > https://git.kernel.org/powerpc/c/5c3c7ede2bdcb85fa2fd51c814 > > I reworded one comment a little, from: > > /* 2^11 PTEGS / 2^18 bytes is the minimum htab size permitted > * by the architecture */ > > to: > /* > * 2^11 PTEGS of 128 bytes each, ie. 2^18 bytes is the minimum htab > * size permitted by the architecture. > */ > > To avoid any confusion about the "/" referring to division. Good call, thanks.
diff --git a/arch/powerpc/include/asm/mmu-hash64.h b/arch/powerpc/include/asm/mmu-hash64.h index 7352d3f..cf070fd 100644 --- a/arch/powerpc/include/asm/mmu-hash64.h +++ b/arch/powerpc/include/asm/mmu-hash64.h @@ -607,6 +607,9 @@ static inline unsigned long get_kernel_vsid(unsigned long ea, int ssize) context = (MAX_USER_CONTEXT) + ((ea >> 60) - 0xc) + 1; return get_vsid(context, ea, ssize); } + +unsigned htab_shift_for_mem_size(unsigned long mem_size); + #endif /* __ASSEMBLY__ */ #endif /* _ASM_POWERPC_MMU_HASH64_H_ */ diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c index fdcf9d1..da5d279 100644 --- a/arch/powerpc/mm/hash_utils_64.c +++ b/arch/powerpc/mm/hash_utils_64.c @@ -611,10 +611,26 @@ static int __init htab_dt_scan_pftsize(unsigned long node, return 0; } -static unsigned long __init htab_get_table_size(void) +unsigned htab_shift_for_mem_size(unsigned long mem_size) { - unsigned long mem_size, rnd_mem_size, pteg_count, psize; + unsigned memshift = __ilog2(mem_size); + unsigned pshift = mmu_psize_defs[mmu_virtual_psize].shift; + unsigned pteg_shift; + + /* round mem_size up to next power of 2 */ + if ((1UL << memshift) < mem_size) + memshift += 1; + + /* aim for 2 pages / pteg */ + pteg_shift = memshift - (pshift + 1); + + /* 2^11 PTEGS / 2^18 bytes is the minimum htab size permitted + * by the architecture */ + return max(pteg_shift + 7, 18U); +} +static unsigned long __init htab_get_table_size(void) +{ /* If hash size isn't already provided by the platform, we try to * retrieve it from the device-tree. If it's not there neither, we * calculate it now based on the total RAM size @@ -624,17 +640,7 @@ static unsigned long __init htab_get_table_size(void) if (ppc64_pft_size) return 1UL << ppc64_pft_size; - /* round mem_size up to next power of 2 */ - mem_size = memblock_phys_mem_size(); - rnd_mem_size = 1UL << __ilog2(mem_size); - if (rnd_mem_size < mem_size) - rnd_mem_size <<= 1; - - /* # pages / 2 */ - psize = mmu_psize_defs[mmu_virtual_psize].shift; - pteg_count = max(rnd_mem_size >> (psize + 1), 1UL << 11); - - return pteg_count << 7; + return 1UL << htab_shift_for_mem_size(memblock_phys_mem_size()); } #ifdef CONFIG_MEMORY_HOTPLUG
htab_get_table_size() either retrieve the size of the hash page table (HPT) from the device tree - if the HPT size is determined by firmware - or uses a heuristic to determine a good size based on RAM size if the kernel is responsible for allocating the HPT. To support a PAPR extension allowing resizing of the HPT, we're going to want the memory size -> HPT size logic elsewhere, so split it out into a helper function. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> --- arch/powerpc/include/asm/mmu-hash64.h | 3 +++ arch/powerpc/mm/hash_utils_64.c | 32 +++++++++++++++++++------------- 2 files changed, 22 insertions(+), 13 deletions(-)