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Re: [Qemu-devel] [PATCH] Revert "memory: syncronize kvm bitmap using bit
From: |
Juan Quintela |
Subject: |
Re: [Qemu-devel] [PATCH] Revert "memory: syncronize kvm bitmap using bitmaps operations" |
Date: |
Wed, 29 Jan 2014 11:39:55 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) |
Alexey Kardashevskiy <address@hidden> wrote:
> On 01/29/2014 06:30 PM, Paolo Bonzini wrote:
>> Il 29/01/2014 06:50, Alexey Kardashevskiy ha scritto:
>>> Since 64K system page size is quite popular configuration on PPC64,
>>> the original patch breaks migration.
>>>
>>> Signed-off-by: Alexey Kardashevskiy <address@hidden>
>>> ---
>>> include/exec/ram_addr.h | 54
>>> +++++++++++++++++--------------------------------
>>> 1 file changed, 18 insertions(+), 36 deletions(-)
>>>
>>> diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
>>> index 33c8acc..c6736ed 100644
>>> --- a/include/exec/ram_addr.h
>>> +++ b/include/exec/ram_addr.h
>>> @@ -83,47 +83,29 @@ static inline void
>>> cpu_physical_memory_set_dirty_lebitmap(unsigned long *bitmap,
>>> ram_addr_t start,
>>> ram_addr_t pages)
>>> {
>>> - unsigned long i, j;
>>> + unsigned int i, j;
>>> unsigned long page_number, c;
>>> hwaddr addr;
>>> ram_addr_t ram_addr;
>>> - unsigned long len = (pages + HOST_LONG_BITS - 1) / HOST_LONG_BITS;
>>> + unsigned int len = (pages + HOST_LONG_BITS - 1) / HOST_LONG_BITS;
>>> unsigned long hpratio = getpagesize() / TARGET_PAGE_SIZE;
>>> - unsigned long page = BIT_WORD(start >> TARGET_PAGE_BITS);
>>>
>>> - /* start address is aligned at the start of a word? */
>>> - if (((page * BITS_PER_LONG) << TARGET_PAGE_BITS) == start) {
>>
>> Why not just add " && hpratio == 1" here?
>
>
> Or fix dirty map to make it 1 bit per system page size (may be the fix is
> coming, who knows, but I am just not ready to do this now). Or do tricks
> with bits and support hpratio!=1. I could not choose and decided to revert
> it for now :)
Please, could you test Paolo suggestion?
> Do we really earn a lot here?
With 512GB guests, we used to have stalls of 10 seconds, now they are
lost on the noise.
Thanks for the testing.
Later, Juan.