95f7142abc
this patch finally introduces multiread support to virtio-blk. While
multiwrite support was there for a long time, read support was missing.
The complete merge logic is moved into virtio-blk.c which has
been the only user of request merging ever since. This is required
to be able to merge chunks of requests and immediately invoke callbacks
for those requests. Secondly, this is required to switch to
direct invocation of coroutines which is planned at a later stage.
The following benchmarks show the performance of running fio with
4 worker threads on a local ram disk. The numbers show the average
of 10 test runs after 1 run as warmup phase.
| 4k | 64k | 4k
MB/s | rd seq | rd rand | rd seq | rd rand | wr seq | wr rand
--------------+--------+---------+--------+---------+--------+--------
master | 1221 | 1187 | 4178 | 4114 | 1745 | 1213
multiread | 1829 | 1189 | 4639 | 4110 | 1894 | 1216
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
166 lines
4.3 KiB
C
166 lines
4.3 KiB
C
/*
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* Virtio Block Device
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*
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* Copyright IBM, Corp. 2007
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*
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*/
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#ifndef _QEMU_VIRTIO_BLK_H
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#define _QEMU_VIRTIO_BLK_H
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#include "hw/virtio/virtio.h"
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#include "hw/block/block.h"
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#include "sysemu/iothread.h"
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#include "sysemu/block-backend.h"
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#define TYPE_VIRTIO_BLK "virtio-blk-device"
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#define VIRTIO_BLK(obj) \
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OBJECT_CHECK(VirtIOBlock, (obj), TYPE_VIRTIO_BLK)
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/* from Linux's linux/virtio_blk.h */
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/* The ID for virtio_block */
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#define VIRTIO_ID_BLOCK 2
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/* Feature bits */
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#define VIRTIO_BLK_F_BARRIER 0 /* Does host support barriers? */
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#define VIRTIO_BLK_F_SIZE_MAX 1 /* Indicates maximum segment size */
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#define VIRTIO_BLK_F_SEG_MAX 2 /* Indicates maximum # of segments */
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#define VIRTIO_BLK_F_GEOMETRY 4 /* Indicates support of legacy geometry */
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#define VIRTIO_BLK_F_RO 5 /* Disk is read-only */
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#define VIRTIO_BLK_F_BLK_SIZE 6 /* Block size of disk is available*/
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#define VIRTIO_BLK_F_SCSI 7 /* Supports scsi command passthru */
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/* #define VIRTIO_BLK_F_IDENTIFY 8 ATA IDENTIFY supported, DEPRECATED */
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#define VIRTIO_BLK_F_WCE 9 /* write cache enabled */
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#define VIRTIO_BLK_F_TOPOLOGY 10 /* Topology information is available */
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#define VIRTIO_BLK_F_CONFIG_WCE 11 /* write cache configurable */
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#define VIRTIO_BLK_ID_BYTES 20 /* ID string length */
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struct virtio_blk_config
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{
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uint64_t capacity;
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uint32_t size_max;
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uint32_t seg_max;
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uint16_t cylinders;
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uint8_t heads;
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uint8_t sectors;
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uint32_t blk_size;
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uint8_t physical_block_exp;
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uint8_t alignment_offset;
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uint16_t min_io_size;
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uint32_t opt_io_size;
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uint8_t wce;
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} QEMU_PACKED;
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/* These two define direction. */
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#define VIRTIO_BLK_T_IN 0
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#define VIRTIO_BLK_T_OUT 1
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/* This bit says it's a scsi command, not an actual read or write. */
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#define VIRTIO_BLK_T_SCSI_CMD 2
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/* Flush the volatile write cache */
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#define VIRTIO_BLK_T_FLUSH 4
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/* return the device ID string */
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#define VIRTIO_BLK_T_GET_ID 8
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/* Barrier before this op. */
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#define VIRTIO_BLK_T_BARRIER 0x80000000
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/* This is the first element of the read scatter-gather list. */
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struct virtio_blk_outhdr
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{
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/* VIRTIO_BLK_T* */
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uint32_t type;
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/* io priority. */
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uint32_t ioprio;
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/* Sector (ie. 512 byte offset) */
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uint64_t sector;
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};
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#define VIRTIO_BLK_S_OK 0
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#define VIRTIO_BLK_S_IOERR 1
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#define VIRTIO_BLK_S_UNSUPP 2
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/* This is the last element of the write scatter-gather list */
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struct virtio_blk_inhdr
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{
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unsigned char status;
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};
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/* SCSI pass-through header */
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struct virtio_scsi_inhdr
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{
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uint32_t errors;
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uint32_t data_len;
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uint32_t sense_len;
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uint32_t residual;
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};
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struct VirtIOBlkConf
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{
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BlockConf conf;
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IOThread *iothread;
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char *serial;
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uint32_t scsi;
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uint32_t config_wce;
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uint32_t data_plane;
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};
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struct VirtIOBlockDataPlane;
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struct VirtIOBlockReq;
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typedef struct VirtIOBlock {
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VirtIODevice parent_obj;
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BlockBackend *blk;
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VirtQueue *vq;
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void *rq;
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QEMUBH *bh;
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VirtIOBlkConf conf;
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unsigned short sector_mask;
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bool original_wce;
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VMChangeStateEntry *change;
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/* Function to push to vq and notify guest */
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void (*complete_request)(struct VirtIOBlockReq *req, unsigned char status);
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Notifier migration_state_notifier;
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struct VirtIOBlockDataPlane *dataplane;
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} VirtIOBlock;
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typedef struct VirtIOBlockReq {
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int64_t sector_num;
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VirtIOBlock *dev;
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VirtQueueElement elem;
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struct virtio_blk_inhdr *in;
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struct virtio_blk_outhdr out;
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QEMUIOVector qiov;
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struct VirtIOBlockReq *next;
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struct VirtIOBlockReq *mr_next;
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BlockAcctCookie acct;
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} VirtIOBlockReq;
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#define VIRTIO_BLK_MAX_MERGE_REQS 32
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typedef struct MultiReqBuffer {
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VirtIOBlockReq *reqs[VIRTIO_BLK_MAX_MERGE_REQS];
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unsigned int num_reqs;
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bool is_write;
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} MultiReqBuffer;
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VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s);
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void virtio_blk_free_request(VirtIOBlockReq *req);
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void virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb);
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void virtio_blk_submit_multireq(BlockBackend *blk, MultiReqBuffer *mrb);
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#endif
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