[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v3 8/9] Use qemu_put_buffer_no_copy for guest me
From: |
Orit Wasserman |
Subject: |
Re: [Qemu-devel] [PATCH v3 8/9] Use qemu_put_buffer_no_copy for guest memory pages |
Date: |
Thu, 21 Mar 2013 20:08:58 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 |
On 03/21/2013 07:37 PM, Juan Quintela wrote:
> Orit Wasserman <address@hidden> wrote:
>> This will remove an unneeded copy of guest memory pages.
>> For the page header and device state we still copy the data to the
>> static buffer the other option is to allocate the memory on demand
>> which is more expensive.
>>
>> Signed-off-by: Orit Wasserman <address@hidden>
>> ---
>> arch_init.c | 2 +-
>> savevm.c | 2 +-
>> 2 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch_init.c b/arch_init.c
>> index 98e2bc6..27b53eb 100644
>> --- a/arch_init.c
>> +++ b/arch_init.c
>> @@ -481,7 +481,7 @@ static int ram_save_block(QEMUFile *f, bool last_stage)
>> /* XBZRLE overflow or normal page */
>> if (bytes_sent == -1) {
>> bytes_sent = save_block_hdr(f, block, offset, cont,
>> RAM_SAVE_FLAG_PAGE);
>> - qemu_put_buffer(f, p, TARGET_PAGE_SIZE);
>> + qemu_put_buffer_no_copy(f, p, TARGET_PAGE_SIZE);
>> bytes_sent += TARGET_PAGE_SIZE;
>> acct_info.norm_pages++;
>> }
>
> Once here, shouldn't we also change:
>
> block-migration.c::blk_send()
>
> qemu_put_buffer(f, blk->buf, BLOCK_SIZE);
>
> to nocopy?
Sadly no, I looked at the code and I saw the buffer is freed immediately
after call blk_send :(. look at mig_save_device_dirty.
Orit
>
> Again, this can be an additional patch.
>
>
>> diff --git a/savevm.c b/savevm.c
>> index fbfb9e3..50e8fb2 100644
>> --- a/savevm.c
>> +++ b/savevm.c
>> @@ -634,7 +634,7 @@ void qemu_put_buffer_no_copy(QEMUFile *f, const uint8_t
>> *buf, int size)
>> abort();
>> }
>>
>> - f->iov[f->iovcnt].iov_base = f->buf + f->buf_index;
>> + f->iov[f->iovcnt].iov_base = (uint8_t *)buf;
>> f->iov[f->iovcnt++].iov_len = size;
>
> This bit should be in the previous patch, the error that I pointed?
>
> Later, Juan.
>
Re: [Qemu-devel] [PATCH v3 9/9] coalesce adjacent iovecs, Juan Quintela, 2013/03/21
[Qemu-devel] [PATCH v3 8/9] Use qemu_put_buffer_no_copy for guest memory pages, Orit Wasserman, 2013/03/21
Re: [Qemu-devel] [PATCH v3 0/9] Migration: Remove copying of guest ram pages, Paolo Bonzini, 2013/03/21
Re: [Qemu-devel] [PATCH v3 0/9] Migration: Remove copying of guest ram pages, Juan Quintela, 2013/03/21