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Re: [Qemu-devel] [PATCH v3 8/9] Use qemu_put_buffer_no_copy for guest me
From: |
Juan Quintela |
Subject: |
Re: [Qemu-devel] [PATCH v3 8/9] Use qemu_put_buffer_no_copy for guest memory pages |
Date: |
Thu, 21 Mar 2013 18:37:05 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.2 (gnu/linux) |
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?
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