[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: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH v3 8/9] Use qemu_put_buffer_no_copy for guest memory pages |
Date: |
Thu, 21 Mar 2013 20:21:00 +0200 |
On Thu, Mar 21, 2013 at 08:08:58PM +0200, Orit Wasserman wrote:
> 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
Hmm if _nocopy also implies it is not safe to free the
buffer immediately, then I'd rather put this in a name
e.g. _async instead of _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, (continued)
- Re: [Qemu-devel] [PATCH v3 9/9] coalesce adjacent iovecs, Michael S. Tsirkin, 2013/03/21
- Re: [Qemu-devel] [PATCH v3 9/9] coalesce adjacent iovecs, Juan Quintela, 2013/03/21
- Re: [Qemu-devel] [PATCH v3 9/9] coalesce adjacent iovecs, Michael S. Tsirkin, 2013/03/21
- Re: [Qemu-devel] [PATCH v3 9/9] coalesce adjacent iovecs, Juan Quintela, 2013/03/21
- Re: [Qemu-devel] [PATCH v3 9/9] coalesce adjacent iovecs, Michael S. Tsirkin, 2013/03/21
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