On Thu, Mar 21, 2013 at 01:10:40PM +0200, Orit Wasserman wrote:
> On 03/21/2013 11:56 AM, Paolo Bonzini wrote:
> > Il 21/03/2013 10:09, Orit Wasserman ha scritto:
> >> All data is still copied into the static buffer.
> >>
> >> Signed-off-by: Orit Wasserman <owass...@redhat.com>
> >> ---
> >> savevm.c | 13 +++++++++++--
> >> 1 file changed, 11 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/savevm.c b/savevm.c
> >> index ec64533..d5834ca 100644
> >> --- a/savevm.c
> >> +++ b/savevm.c
> >> @@ -114,6 +114,7 @@ void qemu_announce_self(void)
> >> /* savevm/loadvm support */
> >>
> >> #define IO_BUF_SIZE 32768
> >> +#define MAX_IOV_SIZE 64
> >
> > You could use IOV_MAX, or min(IOV_MAX, 64).
> Sure
> The 64 should be tuned on a
> > good 10G network...
>
> You need to remember that iovec of 64 is equivalent to 32 guest pages which
> are
> 128K data. This is a large TCP packet that will be fragmented even with jumbo
> frames.
> I can make it configurable but not sure if it will be useful.
> Micheal, what do you think?
>
> Orit
You are both right :). 64 looks like a sane value, and we can
try and tune it some more if we have the time.
> >
> > Paolo
> >
> >> struct QEMUFile {
> >> const QEMUFileOps *ops;
> >> @@ -129,6 +130,9 @@ struct QEMUFile {
> >> int buf_size; /* 0 when writing */
> >> uint8_t buf[IO_BUF_SIZE];
> >>
> >> + struct iovec iov[MAX_IOV_SIZE];
> >> + unsigned int iovcnt;
> >> +
> >> int last_error;
> >> };
> >>
> >> @@ -546,6 +550,7 @@ static void qemu_fflush(QEMUFile *f)
> >> f->pos += f->buf_index;
> >> }
> >> f->buf_index = 0;
> >> + f->iovcnt = 0;
> >> }
> >> if (ret < 0) {
> >> qemu_file_set_error(f, ret);
> >> @@ -638,12 +643,14 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t
> >> *buf, int size)
> >> if (l > size)
> >> l = size;
> >> memcpy(f->buf + f->buf_index, buf, l);
> >> + f->iov[f->iovcnt].iov_base = f->buf + f->buf_index;
> >> + f->iov[f->iovcnt++].iov_len = l;
> >> f->is_write = 1;
> >> f->buf_index += l;
> >> f->bytes_xfer += l;
> >> buf += l;
> >> size -= l;
> >> - if (f->buf_index >= IO_BUF_SIZE) {
> >> + if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) {
> >> qemu_fflush(f);
> >> if (qemu_file_get_error(f)) {
> >> break;
> >> @@ -667,8 +674,10 @@ void qemu_put_byte(QEMUFile *f, int v)
> >> f->buf[f->buf_index++] = v;
> >> f->is_write = 1;
> >> f->bytes_xfer += 1;
> >> + f->iov[f->iovcnt].iov_base = f->buf + (f->buf_index - 1);
> >> + f->iov[f->iovcnt++].iov_len = 1;
> >>
> >> - if (f->buf_index >= IO_BUF_SIZE) {
> >> + if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) {
> >> qemu_fflush(f);
> >> }
> >> }
> >>
> >
