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[Qemu-devel] [PATCH v5 4/7] Store the data to send also in iovec
From: |
Orit Wasserman |
Subject: |
[Qemu-devel] [PATCH v5 4/7] Store the data to send also in iovec |
Date: |
Fri, 22 Mar 2013 16:48:00 +0200 |
All data is still copied into the static buffer.
Adjacent iovecs are coalesced so we send one big buffer
instead of many small buffers.
Signed-off-by: Orit Wasserman <address@hidden>
---
savevm.c | 24 ++++++++++++++++++++++--
1 file changed, 22 insertions(+), 2 deletions(-)
diff --git a/savevm.c b/savevm.c
index 2ba0d85..8dad9ef 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 MIN(IOV_MAX, 64)
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;
};
@@ -528,6 +532,7 @@ 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);
@@ -601,6 +606,18 @@ int qemu_fclose(QEMUFile *f)
return ret;
}
+static void add_to_iovec(QEMUFile *f, const uint8_t *buf, int size)
+{
+ /* check for adjacent buffer and coalesce them */
+ if (f->iovcnt > 0 && buf == f->iov[f->iovcnt - 1].iov_base +
+ f->iov[f->iovcnt - 1].iov_len) {
+ f->iov[f->iovcnt - 1].iov_len += size;
+ } else {
+ f->iov[f->iovcnt].iov_base = (uint8_t *)buf;
+ f->iov[f->iovcnt++].iov_len = size;
+ }
+}
+
void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size)
{
int l;
@@ -620,12 +637,13 @@ 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);
+ add_to_iovec(f, f->buf + f->buf_index, 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;
@@ -650,7 +668,9 @@ void qemu_put_byte(QEMUFile *f, int v)
f->is_write = 1;
f->bytes_xfer++;
- if (f->buf_index >= IO_BUF_SIZE) {
+ add_to_iovec(f, f->buf + (f->buf_index - 1), 1);
+
+ if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) {
qemu_fflush(f);
}
}
--
1.7.11.7
- [Qemu-devel] [PATCH v5 0/7] Migration: Remove copying of guest ram pages, Orit Wasserman, 2013/03/22
- [Qemu-devel] [PATCH v5 1/7] Add QemuFileWritevBuffer QemuFileOps, Orit Wasserman, 2013/03/22
- [Qemu-devel] [PATCH v5 2/7] Add socket_writev_buffer function, Orit Wasserman, 2013/03/22
- [Qemu-devel] [PATCH v5 3/7] Update bytes_xfer in qemu_put_byte, Orit Wasserman, 2013/03/22
- [Qemu-devel] [PATCH v5 4/7] Store the data to send also in iovec,
Orit Wasserman <=
- [Qemu-devel] [PATCH v5 5/7] Use writev ops if available, Orit Wasserman, 2013/03/22
- [Qemu-devel] [PATCH v5 6/7] Add qemu_put_buffer_async, Orit Wasserman, 2013/03/22
- [Qemu-devel] [PATCH v5 7/7] Use qemu_put_buffer_async for guest memory pages, Orit Wasserman, 2013/03/22
- Re: [Qemu-devel] [PATCH v5 0/7] Migration: Remove copying of guest ram pages, Eric Blake, 2013/03/27