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authorPaolo Bonzini <pbonzini@redhat.com>2013-04-08 13:29:55 +0200
committerJuan Quintela <quintela@redhat.com>2013-04-09 15:00:13 +0200
commit7ce51f1b8157a2aa6bd3945bba9904442d3c3cdd (patch)
tree6c13c0a135b4c917c75f13365221fe4dd87c3edd /savevm.c
parentaf74db72d33e4776d7d1430b57d0bf065a6f03df (diff)
downloadqemu-arm-7ce51f1b8157a2aa6bd3945bba9904442d3c3cdd.tar.gz
migration: use a single I/O operation when writev_buffer is not defined
The recent patches to use vectored I/O for RAM migration caused a regression in savevm speed. To restore previous performance, add data to the buffer in qemu_put_buffer_async whenever writev_buffer is not available in the QEMUFile. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Juan Quintela <quintela@redhat.com>
Diffstat (limited to 'savevm.c')
-rw-r--r--savevm.c49
1 files changed, 34 insertions, 15 deletions
diff --git a/savevm.c b/savevm.c
index c952c41057..b32e0a7fa1 100644
--- a/savevm.c
+++ b/savevm.c
@@ -525,27 +525,24 @@ static void qemu_file_set_error(QEMUFile *f, int ret)
static void qemu_fflush(QEMUFile *f)
{
ssize_t ret = 0;
- int i = 0;
if (!f->ops->writev_buffer && !f->ops->put_buffer) {
return;
}
- if (f->is_write && f->iovcnt > 0) {
+ if (f->is_write) {
if (f->ops->writev_buffer) {
- ret = f->ops->writev_buffer(f->opaque, f->iov, f->iovcnt);
- if (ret >= 0) {
- f->pos += ret;
+ if (f->iovcnt > 0) {
+ ret = f->ops->writev_buffer(f->opaque, f->iov, f->iovcnt);
}
} else {
- for (i = 0; i < f->iovcnt && ret >= 0; i++) {
- ret = f->ops->put_buffer(f->opaque, f->iov[i].iov_base, f->pos,
- f->iov[i].iov_len);
- if (ret >= 0) {
- f->pos += ret;
- }
+ if (f->buf_index > 0) {
+ ret = f->ops->put_buffer(f->opaque, f->buf, f->pos, f->buf_index);
}
}
+ if (ret >= 0) {
+ f->pos += ret;
+ }
f->buf_index = 0;
f->iovcnt = 0;
}
@@ -640,6 +637,11 @@ static void add_to_iovec(QEMUFile *f, const uint8_t *buf, int size)
void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, int size)
{
+ if (!f->ops->writev_buffer) {
+ qemu_put_buffer(f, buf, size);
+ return;
+ }
+
if (f->last_error) {
return;
}
@@ -673,8 +675,17 @@ 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->buf_index += l;
- qemu_put_buffer_async(f, f->buf + (f->buf_index - l), l);
+ f->bytes_xfer += size;
+ if (f->ops->writev_buffer) {
+ add_to_iovec(f, f->buf + f->buf_index, l);
+ f->buf_index += l;
+ } else {
+ f->is_write = 1;
+ f->buf_index += l;
+ if (f->buf_index == IO_BUF_SIZE) {
+ qemu_fflush(f);
+ }
+ }
if (qemu_file_get_error(f)) {
break;
}
@@ -697,8 +708,16 @@ void qemu_put_byte(QEMUFile *f, int v)
f->buf[f->buf_index] = v;
f->bytes_xfer++;
- add_to_iovec(f, f->buf + f->buf_index, 1);
- f->buf_index++;
+ if (f->ops->writev_buffer) {
+ add_to_iovec(f, f->buf + f->buf_index, 1);
+ f->buf_index++;
+ } else {
+ f->is_write = 1;
+ f->buf_index++;
+ if (f->buf_index == IO_BUF_SIZE) {
+ qemu_fflush(f);
+ }
+ }
}
static void qemu_file_skip(QEMUFile *f, int size)