[Qemu-devel] [PULL 49/57] Round up RAMBlock sizes to host page sizes
From: "Dr. David Alan Gilbert"
RAMBlocks that are not a multiple of host pages in length
cause problems for postcopy (I've seen an ACPI table on aarch64
be 5k in length - i.e. 5x target-page), so round RAMBlock sizes
up to a host-page.
This potentially breaks migration compatibility due to changes
in RAMBlock sizes; however:
1) x86 and s390 I think always have host=target page size
2) When I've tried on Power the block sizes already seem aligned.
3) I don't think there's anything else that maintains per-version
machine-types for compatibility.
Signed-off-by: Dr. David Alan Gilbert
Reviewed-by: Juan Quintela
Signed-off-by: Juan Quintela
---
exec.c | 8
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/exec.c b/exec.c
index 36886ee..b09f18b 100644
--- a/exec.c
+++ b/exec.c
@@ -1452,7 +1452,7 @@ int qemu_ram_resize(ram_addr_t base, ram_addr_t newsize,
Error **errp)
assert(block);
-newsize = TARGET_PAGE_ALIGN(newsize);
+newsize = HOST_PAGE_ALIGN(newsize);
if (block->used_length == newsize) {
return 0;
@@ -1596,7 +1596,7 @@ ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size,
MemoryRegion *mr,
return -1;
}
-size = TARGET_PAGE_ALIGN(size);
+size = HOST_PAGE_ALIGN(size);
new_block = g_malloc0(sizeof(*new_block));
new_block->mr = mr;
new_block->used_length = size;
@@ -1632,8 +1632,8 @@ ram_addr_t qemu_ram_alloc_internal(ram_addr_t size,
ram_addr_t max_size,
ram_addr_t addr;
Error *local_err = NULL;
-size = TARGET_PAGE_ALIGN(size);
-max_size = TARGET_PAGE_ALIGN(max_size);
+size = HOST_PAGE_ALIGN(size);
+max_size = HOST_PAGE_ALIGN(max_size);
new_block = g_malloc0(sizeof(*new_block));
new_block->mr = mr;
new_block->resized = resized;
--
2.5.0
[Qemu-devel] [PULL 49/57] Round up RAMBlock sizes to host page sizes
From: "Dr. David Alan Gilbert"
RAMBlocks that are not a multiple of host pages in length
cause problems for postcopy (I've seen an ACPI table on aarch64
be 5k in length - i.e. 5x target-page), so round RAMBlock sizes
up to a host-page.
This potentially breaks migration compatibility due to changes
in RAMBlock sizes; however:
1) x86 and s390 I think always have host=target page size
2) When I've tried on Power the block sizes already seem aligned.
3) I don't think there's anything else that maintains per-version
machine-types for compatibility.
Signed-off-by: Dr. David Alan Gilbert
Reviewed-by: Juan Quintela
Signed-off-by: Juan Quintela
---
exec.c | 8
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/exec.c b/exec.c
index 36886ee..b09f18b 100644
--- a/exec.c
+++ b/exec.c
@@ -1452,7 +1452,7 @@ int qemu_ram_resize(ram_addr_t base, ram_addr_t newsize,
Error **errp)
assert(block);
-newsize = TARGET_PAGE_ALIGN(newsize);
+newsize = HOST_PAGE_ALIGN(newsize);
if (block->used_length == newsize) {
return 0;
@@ -1596,7 +1596,7 @@ ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size,
MemoryRegion *mr,
return -1;
}
-size = TARGET_PAGE_ALIGN(size);
+size = HOST_PAGE_ALIGN(size);
new_block = g_malloc0(sizeof(*new_block));
new_block->mr = mr;
new_block->used_length = size;
@@ -1632,8 +1632,8 @@ ram_addr_t qemu_ram_alloc_internal(ram_addr_t size,
ram_addr_t max_size,
ram_addr_t addr;
Error *local_err = NULL;
-size = TARGET_PAGE_ALIGN(size);
-max_size = TARGET_PAGE_ALIGN(max_size);
+size = HOST_PAGE_ALIGN(size);
+max_size = HOST_PAGE_ALIGN(max_size);
new_block = g_malloc0(sizeof(*new_block));
new_block->mr = mr;
new_block->resized = resized;
--
2.5.0
Re: [Qemu-devel] [PULL 49/57] Round up RAMBlock sizes to host page sizes
On 30/12/2015 01:26, Peter Crosthwaite wrote:
> On Tue, Nov 10, 2015 at 6:25 AM, Juan Quintela wrote:
>> From: "Dr. David Alan Gilbert"
>>
>> RAMBlocks that are not a multiple of host pages in length
>> cause problems for postcopy (I've seen an ACPI table on aarch64
>> be 5k in length - i.e. 5x target-page), so round RAMBlock sizes
>> up to a host-page.
>>
>> This potentially breaks migration compatibility due to changes
>> in RAMBlock sizes; however:
>>1) x86 and s390 I think always have host=target page size
>>2) When I've tried on Power the block sizes already seem aligned.
>>3) I don't think there's anything else that maintains per-version
>> machine-types for compatibility.
>>
>
> Is there any reason this shouldn't be converted to
> REAL_HOST_PAGE_ALIGN given these restrictions?
>
> I'm thinking about multi-arch, where HOST_PAGE_ALIGN is inaccessible
> from exec.c as it is target-arch specific. My previous workaround was
> to define the target page size for multi-arch so that TARGET_PAGE_SIZE
> was usable but not sure that should go viral to these other defs.
host_page_size and host_page_mask are really just MAX(host_page_size,
TARGET_PAGE_SIZE) and MIN(qemu_host_page_mask, TARGET_PAGE_MASK). If
you convert them to macros this way, the hack you use for multi-arch
TARGET_PAGE_SIZE will work transparently for HOST_PAGE_{SIZE,MASK}.
Paolo
Re: [Qemu-devel] [PULL 49/57] Round up RAMBlock sizes to host page sizes
On Tue, Nov 10, 2015 at 6:25 AM, Juan Quintela wrote:
> From: "Dr. David Alan Gilbert"
>
> RAMBlocks that are not a multiple of host pages in length
> cause problems for postcopy (I've seen an ACPI table on aarch64
> be 5k in length - i.e. 5x target-page), so round RAMBlock sizes
> up to a host-page.
>
> This potentially breaks migration compatibility due to changes
> in RAMBlock sizes; however:
>1) x86 and s390 I think always have host=target page size
>2) When I've tried on Power the block sizes already seem aligned.
>3) I don't think there's anything else that maintains per-version
> machine-types for compatibility.
>
Is there any reason this shouldn't be converted to
REAL_HOST_PAGE_ALIGN given these restrictions?
I'm thinking about multi-arch, where HOST_PAGE_ALIGN is inaccessible
from exec.c as it is target-arch specific. My previous workaround was
to define the target page size for multi-arch so that TARGET_PAGE_SIZE
was usable but not sure that should go viral to these other defs.
The other approach, is to calculate the lowest common denominator for
the page size accross the multi-arch targets (+ the host) for the
implementation of HOST_PAGE_ALIGN and friends.
Regards,
Peter
> Signed-off-by: Dr. David Alan Gilbert
> Reviewed-by: Juan Quintela
> Signed-off-by: Juan Quintela
> ---
> exec.c | 8
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/exec.c b/exec.c
> index 36886ee..b09f18b 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -1452,7 +1452,7 @@ int qemu_ram_resize(ram_addr_t base, ram_addr_t
> newsize, Error **errp)
>
> assert(block);
>
> -newsize = TARGET_PAGE_ALIGN(newsize);
> +newsize = HOST_PAGE_ALIGN(newsize);
>
> if (block->used_length == newsize) {
> return 0;
> @@ -1596,7 +1596,7 @@ ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size,
> MemoryRegion *mr,
> return -1;
> }
>
> -size = TARGET_PAGE_ALIGN(size);
> +size = HOST_PAGE_ALIGN(size);
> new_block = g_malloc0(sizeof(*new_block));
> new_block->mr = mr;
> new_block->used_length = size;
> @@ -1632,8 +1632,8 @@ ram_addr_t qemu_ram_alloc_internal(ram_addr_t size,
> ram_addr_t max_size,
> ram_addr_t addr;
> Error *local_err = NULL;
>
> -size = TARGET_PAGE_ALIGN(size);
> -max_size = TARGET_PAGE_ALIGN(max_size);
> +size = HOST_PAGE_ALIGN(size);
> +max_size = HOST_PAGE_ALIGN(max_size);
> new_block = g_malloc0(sizeof(*new_block));
> new_block->mr = mr;
> new_block->resized = resized;
> --
> 2.5.0
>
>
Re: [Qemu-devel] [PULL 49/57] Round up RAMBlock sizes to host page sizes
* Peter Crosthwaite (crosthwaitepe...@gmail.com) wrote:
> On Tue, Nov 10, 2015 at 6:25 AM, Juan Quintela wrote:
> > From: "Dr. David Alan Gilbert"
> >
> > RAMBlocks that are not a multiple of host pages in length
> > cause problems for postcopy (I've seen an ACPI table on aarch64
> > be 5k in length - i.e. 5x target-page), so round RAMBlock sizes
> > up to a host-page.
> >
> > This potentially breaks migration compatibility due to changes
> > in RAMBlock sizes; however:
> >1) x86 and s390 I think always have host=target page size
> >2) When I've tried on Power the block sizes already seem aligned.
> >3) I don't think there's anything else that maintains per-version
> > machine-types for compatibility.
> >
>
> Is there any reason this shouldn't be converted to
> REAL_HOST_PAGE_ALIGN given these restrictions?
If I remember correctly the only time host_page_size and real_host_page_size
are different is the odd case where host_page_size < target_page_size;
since we need to ensure alignment to the larger of the two, I don't
think it's right to use real_host_page_size, since you might be aligning
to something smaller than target_page_size.
(I don't know if migration already works in that case anyway)
> I'm thinking about multi-arch, where HOST_PAGE_ALIGN is inaccessible
> from exec.c as it is target-arch specific. My previous workaround was
> to define the target page size for multi-arch so that TARGET_PAGE_SIZE
> was usable but not sure that should go viral to these other defs.
Would it help to move qemu_ram_resize elsewhere?
> The other approach, is to calculate the lowest common denominator for
> the page size accross the multi-arch targets (+ the host) for the
> implementation of HOST_PAGE_ALIGN and friends.
I'm not sure I understand what happens to the migration bitmaps in multi-arch;
the bitmaps are one bit per target-page.
Dave
>
> Regards,
> Peter
>
> > Signed-off-by: Dr. David Alan Gilbert
> > Reviewed-by: Juan Quintela
> > Signed-off-by: Juan Quintela
> > ---
> > exec.c | 8
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/exec.c b/exec.c
> > index 36886ee..b09f18b 100644
> > --- a/exec.c
> > +++ b/exec.c
> > @@ -1452,7 +1452,7 @@ int qemu_ram_resize(ram_addr_t base, ram_addr_t
> > newsize, Error **errp)
> >
> > assert(block);
> >
> > -newsize = TARGET_PAGE_ALIGN(newsize);
> > +newsize = HOST_PAGE_ALIGN(newsize);
> >
> > if (block->used_length == newsize) {
> > return 0;
> > @@ -1596,7 +1596,7 @@ ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size,
> > MemoryRegion *mr,
> > return -1;
> > }
> >
> > -size = TARGET_PAGE_ALIGN(size);
> > +size = HOST_PAGE_ALIGN(size);
> > new_block = g_malloc0(sizeof(*new_block));
> > new_block->mr = mr;
> > new_block->used_length = size;
> > @@ -1632,8 +1632,8 @@ ram_addr_t qemu_ram_alloc_internal(ram_addr_t size,
> > ram_addr_t max_size,
> > ram_addr_t addr;
> > Error *local_err = NULL;
> >
> > -size = TARGET_PAGE_ALIGN(size);
> > -max_size = TARGET_PAGE_ALIGN(max_size);
> > +size = HOST_PAGE_ALIGN(size);
> > +max_size = HOST_PAGE_ALIGN(max_size);
> > new_block = g_malloc0(sizeof(*new_block));
> > new_block->mr = mr;
> > new_block->resized = resized;
> > --
> > 2.5.0
> >
> >
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
