On 03/21/2013 01:14 PM, Michael S. Tsirkin wrote: > 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, are you ok with leaving it MIN(IOV_MAX, 64) at the moment? Later we can make it changeable.
Orit >>> >>> 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); >>>> } >>>> } >>>> >>>