Re: [PATCH 5/5] arch: simplify several early memory allocations
On Mon, Nov 26, 2018 at 12:21:34AM -0800, Christoph Hellwig wrote:
> > static void __init *early_alloc_aligned(unsigned long sz, unsigned long
> > align)
> > {
> > - void *ptr = __va(memblock_phys_alloc(sz, align));
> > - memset(ptr, 0, sz);
> > - return ptr;
> > + return memblock_alloc(sz, align);
> > }
>
> What is the point of keeping this wrapper?
No point indeed. I'll remove it in v2.
> > static void __init *early_alloc(unsigned long sz)
> > {
> > - void *ptr = __va(memblock_phys_alloc(sz, sz));
> > - memset(ptr, 0, sz);
> > - return ptr;
> > + return memblock_alloc(sz, sz);
> > }
>
> Same here.
>
Here it provides a shortcut for allocations with align == size, but can be
removed as well.
--
Sincerely yours,
Mike.
Re: [PATCH 5/5] arch: simplify several early memory allocations
> static void __init *early_alloc_aligned(unsigned long sz, unsigned long
> align)
> {
> - void *ptr = __va(memblock_phys_alloc(sz, align));
> - memset(ptr, 0, sz);
> - return ptr;
> + return memblock_alloc(sz, align);
> }
What is the point of keeping this wrapper?
> static void __init *early_alloc(unsigned long sz)
> {
> - void *ptr = __va(memblock_phys_alloc(sz, sz));
> - memset(ptr, 0, sz);
> - return ptr;
> + return memblock_alloc(sz, sz);
> }
Same here.
Re: [PATCH 5/5] arch: simplify several early memory allocations
On Mon, Nov 26, 2018 at 08:03:55AM +0100, Christophe LEROY wrote:
>
>
> Le 25/11/2018 à 22:44, Mike Rapoport a écrit :
> >There are several early memory allocations in arch/ code that use
> >memblock_phys_alloc() to allocate memory, convert the returned physical
> >address to the virtual address and then set the allocated memory to zero.
> >
> >Exactly the same behaviour can be achieved simply by calling
> >memblock_alloc(): it allocates the memory in the same way as
> >memblock_phys_alloc(), then it performs the phys_to_virt() conversion and
> >clears the allocated memory.
> >
> >Replace the longer sequence with a simpler call to memblock_alloc().
> >
> >Signed-off-by: Mike Rapoport
> >---
> > arch/arm/mm/mmu.c | 4 +---
> > arch/c6x/mm/dma-coherent.c| 9 ++---
> > arch/nds32/mm/init.c | 12
> > arch/powerpc/kernel/setup-common.c| 4 ++--
> > arch/powerpc/mm/pgtable_32.c | 4 +---
> > arch/powerpc/mm/ppc_mmu_32.c | 3 +--
> > arch/powerpc/platforms/powernv/opal.c | 3 +--
> > arch/sparc/kernel/prom_64.c | 7 ++-
> > arch/sparc/mm/init_64.c | 9 +++--
> > arch/unicore32/mm/mmu.c | 4 +---
> > 10 files changed, 18 insertions(+), 41 deletions(-)
> >
> [...]
>
> >diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
> >index bda3c6f..9931e68 100644
> >--- a/arch/powerpc/mm/pgtable_32.c
> >+++ b/arch/powerpc/mm/pgtable_32.c
> >@@ -50,9 +50,7 @@ __ref pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
> >unsigned long address)
> > if (slab_is_available()) {
> > pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
> > } else {
> >-pte = __va(memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE));
> >-if (pte)
> >-clear_page(pte);
> >+pte = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
>
> memblock_alloc() uses memset to zeroize the block.
>
> clear_page() is more performant than memset().
As far as I can tell, the majority of the page table pages will be anyway
allocated with __get_free_page() so I think the performance loss here will
negligible.
> Christophe
>
> [...]
>
--
Sincerely yours,
Mike.
Re: [PATCH 5/5] arch: simplify several early memory allocations
Le 25/11/2018 à 22:44, Mike Rapoport a écrit :
There are several early memory allocations in arch/ code that use
memblock_phys_alloc() to allocate memory, convert the returned physical
address to the virtual address and then set the allocated memory to zero.
Exactly the same behaviour can be achieved simply by calling
memblock_alloc(): it allocates the memory in the same way as
memblock_phys_alloc(), then it performs the phys_to_virt() conversion and
clears the allocated memory.
Replace the longer sequence with a simpler call to memblock_alloc().
Signed-off-by: Mike Rapoport
---
arch/arm/mm/mmu.c | 4 +---
arch/c6x/mm/dma-coherent.c| 9 ++---
arch/nds32/mm/init.c | 12
arch/powerpc/kernel/setup-common.c| 4 ++--
arch/powerpc/mm/pgtable_32.c | 4 +---
arch/powerpc/mm/ppc_mmu_32.c | 3 +--
arch/powerpc/platforms/powernv/opal.c | 3 +--
arch/sparc/kernel/prom_64.c | 7 ++-
arch/sparc/mm/init_64.c | 9 +++--
arch/unicore32/mm/mmu.c | 4 +---
10 files changed, 18 insertions(+), 41 deletions(-)
[...]
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index bda3c6f..9931e68 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -50,9 +50,7 @@ __ref pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
unsigned long address)
if (slab_is_available()) {
pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
} else {
- pte = __va(memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE));
- if (pte)
- clear_page(pte);
+ pte = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
memblock_alloc() uses memset to zeroize the block.
clear_page() is more performant than memset().
Christophe
[...]
