qemu/include/hw/virtio/virtio-blk.h
Stefan Hajnoczi 9445e1e15e virtio-blk-pci: default num_queues to -smp N
Automatically size the number of virtio-blk-pci request virtqueues to
match the number of vCPUs.  Other transports continue to default to 1
request virtqueue.

A 1:1 virtqueue:vCPU mapping ensures that completion interrupts are
handled on the same vCPU that submitted the request.  No IPI is
necessary to complete an I/O request and performance is improved.  The
maximum number of MSI-X vectors and virtqueues limit are respected.

Performance improves from 78k to 104k IOPS on a 32 vCPU guest with 101
virtio-blk-pci devices (ioengine=libaio, iodepth=1, bs=4k, rw=randread
with NVMe storage).

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Message-Id: <20200818143348.310613-7-stefanha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2020-08-27 08:29:13 -04:00

94 lines
2.1 KiB
C

/*
* Virtio Block Device
*
* Copyright IBM, Corp. 2007
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
*/
#ifndef QEMU_VIRTIO_BLK_H
#define QEMU_VIRTIO_BLK_H
#include "standard-headers/linux/virtio_blk.h"
#include "hw/virtio/virtio.h"
#include "hw/block/block.h"
#include "sysemu/iothread.h"
#include "sysemu/block-backend.h"
#define TYPE_VIRTIO_BLK "virtio-blk-device"
#define VIRTIO_BLK(obj) \
OBJECT_CHECK(VirtIOBlock, (obj), TYPE_VIRTIO_BLK)
/* This is the last element of the write scatter-gather list */
struct virtio_blk_inhdr
{
unsigned char status;
};
#define VIRTIO_BLK_AUTO_NUM_QUEUES UINT16_MAX
struct VirtIOBlkConf
{
BlockConf conf;
IOThread *iothread;
char *serial;
uint32_t request_merging;
uint16_t num_queues;
uint16_t queue_size;
bool seg_max_adjust;
uint32_t max_discard_sectors;
uint32_t max_write_zeroes_sectors;
bool x_enable_wce_if_config_wce;
};
struct VirtIOBlockDataPlane;
struct VirtIOBlockReq;
typedef struct VirtIOBlock {
VirtIODevice parent_obj;
BlockBackend *blk;
void *rq;
QEMUBH *bh;
VirtIOBlkConf conf;
unsigned short sector_mask;
bool original_wce;
VMChangeStateEntry *change;
bool dataplane_disabled;
bool dataplane_started;
struct VirtIOBlockDataPlane *dataplane;
uint64_t host_features;
size_t config_size;
} VirtIOBlock;
typedef struct VirtIOBlockReq {
VirtQueueElement elem;
int64_t sector_num;
VirtIOBlock *dev;
VirtQueue *vq;
struct virtio_blk_inhdr *in;
struct virtio_blk_outhdr out;
QEMUIOVector qiov;
size_t in_len;
struct VirtIOBlockReq *next;
struct VirtIOBlockReq *mr_next;
BlockAcctCookie acct;
} VirtIOBlockReq;
#define VIRTIO_BLK_MAX_MERGE_REQS 32
typedef struct MultiReqBuffer {
VirtIOBlockReq *reqs[VIRTIO_BLK_MAX_MERGE_REQS];
unsigned int num_reqs;
bool is_write;
} MultiReqBuffer;
bool virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq);
void virtio_blk_process_queued_requests(VirtIOBlock *s, bool is_bh);
#endif