Add an option "iothread=x" to do emulation in a seperate iothread.
This improves the performance because QEMU's main loop is responsible
for a lot of other work while iothread is dedicated to NVMe emulation.
Moreover, emulating in iothread brings the potential of polling on
SQ/CQ doorbells, which I will bring up in a following patch.
Iothread can be enabled by:
-object iothread,id=nvme0 \
-device nvme,iothread=nvme0 \
Performance comparisons (KIOPS):
QD 1 4 16 64
QEMU 41 136 242 338
iothread 53 155 245 309
Signed-off-by: Jinhao Fan <fanjinhao...@ict.ac.cn>
---
hw/nvme/ctrl.c | 67 ++++++++++++++++++++++++++++++++++++++++++++------
hw/nvme/ns.c | 21 +++++++++++++---
hw/nvme/nvme.h | 6 ++++-
3 files changed, 82 insertions(+), 12 deletions(-)
diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
index e11328967f..869565d77b 100644
--- a/hw/nvme/ctrl.c
+++ b/hw/nvme/ctrl.c
@@ -4458,7 +4458,13 @@ static int nvme_init_cq_ioeventfd(NvmeCQueue *cq)
return ret;
}
- event_notifier_set_handler(&cq->notifier, nvme_cq_notifier);
+ if (cq->cqid) {
+ aio_set_event_notifier(n->ctx, &cq->notifier, true, nvme_cq_notifier,
+ NULL, NULL);
+ } else {
+ event_notifier_set_handler(&cq->notifier, nvme_cq_notifier);
+ }
+
memory_region_add_eventfd(&n->iomem,
0x1000 + offset, 4, false, 0, &cq->notifier);
@@ -4487,7 +4493,13 @@ static int nvme_init_sq_ioeventfd(NvmeSQueue *sq)
return ret;
}
- event_notifier_set_handler(&sq->notifier, nvme_sq_notifier);
+ if (sq->sqid) {
+ aio_set_event_notifier(n->ctx, &sq->notifier, true, nvme_sq_notifier,
+ NULL, NULL);
+ } else {
+ event_notifier_set_handler(&sq->notifier, nvme_sq_notifier);
+ }
+
memory_region_add_eventfd(&n->iomem,
0x1000 + offset, 4, false, 0, &sq->notifier);
@@ -4503,7 +4515,12 @@ static void nvme_free_sq(NvmeSQueue *sq, NvmeCtrl *n)
if (sq->ioeventfd_enabled) {
memory_region_del_eventfd(&n->iomem,
0x1000 + offset, 4, false, 0, &sq->notifier);
- event_notifier_set_handler(&sq->notifier, NULL);
+ if (sq->sqid) {
+ aio_set_event_notifier(n->ctx, &sq->notifier, true, NULL, NULL,
+ NULL);
+ } else {
+ event_notifier_set_handler(&sq->notifier, NULL);
+ }
event_notifier_cleanup(&sq->notifier);
}
g_free(sq->io_req);
@@ -4573,7 +4590,13 @@ static void nvme_init_sq(NvmeSQueue *sq, NvmeCtrl *n,
uint64_t dma_addr,
sq->io_req[i].sq = sq;
QTAILQ_INSERT_TAIL(&(sq->req_list), &sq->io_req[i], entry);
}
- sq->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, nvme_process_sq, sq);
+
+ if (sq->sqid) {
+ sq->timer = aio_timer_new(n->ctx, QEMU_CLOCK_VIRTUAL, SCALE_NS,
+ nvme_process_sq, sq);
+ } else {
+ sq->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, nvme_process_sq, sq);
+ }
if (n->dbbuf_enabled) {
sq->db_addr = n->dbbuf_dbs + (sqid << 3);
@@ -4896,7 +4919,12 @@ static void nvme_free_cq(NvmeCQueue *cq, NvmeCtrl *n)
if (cq->ioeventfd_enabled) {
memory_region_del_eventfd(&n->iomem,
0x1000 + offset, 4, false, 0, &cq->notifier);
- event_notifier_set_handler(&cq->notifier, NULL);
+ if (cq->cqid) {
+ aio_set_event_notifier(n->ctx, &cq->notifier, true, NULL, NULL,
+ NULL);
+ } else {
+ event_notifier_set_handler(&cq->notifier, NULL);
+ }
event_notifier_cleanup(&cq->notifier);
}
if (cq->assert_notifier.initialized) {
@@ -4979,7 +5007,13 @@ static void nvme_init_cq(NvmeCQueue *cq, NvmeCtrl *n,
uint64_t dma_addr,
}
}
n->cq[cqid] = cq;
- cq->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, nvme_post_cqes, cq);
+
+ if (cq->cqid) {
+ cq->timer = aio_timer_new(n->ctx, QEMU_CLOCK_VIRTUAL, SCALE_NS,
+ nvme_post_cqes, cq);
+ } else {
+ cq->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, nvme_post_cqes, cq);
+ }
/*
* Only enable irq eventfd for IO queues since we always emulate admin
@@ -7759,6 +7793,14 @@ static void nvme_init_ctrl(NvmeCtrl *n, PCIDevice
*pci_dev)
if (pci_is_vf(&n->parent_obj) && !sctrl->scs) {
stl_le_p(&n->bar.csts, NVME_CSTS_FAILED);
}
+
+ if (n->params.iothread) {
+ n->iothread = n->params.iothread;
+ object_ref(OBJECT(n->iothread));
+ n->ctx = iothread_get_aio_context(n->iothread);
+ } else {
+ n->ctx = qemu_get_aio_context();
+ }
}
static int nvme_init_subsys(NvmeCtrl *n, Error **errp)
@@ -7831,7 +7873,7 @@ static void nvme_realize(PCIDevice *pci_dev, Error **errp)
ns = &n->namespace;
ns->params.nsid = 1;
- if (nvme_ns_setup(ns, errp)) {
+ if (nvme_ns_setup(ns, n->ctx, errp)) {
return;
}
@@ -7862,6 +7904,15 @@ static void nvme_exit(PCIDevice *pci_dev)
g_free(n->sq);
g_free(n->aer_reqs);
+ aio_context_acquire(n->ctx);
+ blk_set_aio_context(n->namespace.blkconf.blk, qemu_get_aio_context(),
NULL);
+ aio_context_release(n->ctx);
+
+ if (n->iothread) {
+ object_unref(OBJECT(n->iothread));
+ n->iothread = NULL;
+ }
+
if (n->params.cmb_size_mb) {
g_free(n->cmb.buf);
}
@@ -7885,6 +7936,8 @@ static Property nvme_props[] = {
HostMemoryBackend *),
DEFINE_PROP_LINK("subsys", NvmeCtrl, subsys, TYPE_NVME_SUBSYS,
NvmeSubsystem *),
+ DEFINE_PROP_LINK("iothread", NvmeCtrl, params.iothread, TYPE_IOTHREAD,
+ IOThread *),
DEFINE_PROP_STRING("serial", NvmeCtrl, params.serial),
DEFINE_PROP_UINT32("cmb_size_mb", NvmeCtrl, params.cmb_size_mb, 0),
DEFINE_PROP_UINT32("num_queues", NvmeCtrl, params.num_queues, 0),
diff --git a/hw/nvme/ns.c b/hw/nvme/ns.c
index 62a1f97be0..eb9141a67b 100644
--- a/hw/nvme/ns.c
+++ b/hw/nvme/ns.c
@@ -146,9 +146,11 @@ lbaf_found:
return 0;
}
-static int nvme_ns_init_blk(NvmeNamespace *ns, Error **errp)
+static int nvme_ns_init_blk(NvmeNamespace *ns, AioContext *ctx, Error **errp)
{
bool read_only;
+ AioContext *old_context;
+ int ret;
if (!blkconf_blocksizes(&ns->blkconf, errp)) {
return -1;
@@ -170,6 +172,17 @@ static int nvme_ns_init_blk(NvmeNamespace *ns, Error
**errp)
return -1;
}
+ old_context = blk_get_aio_context(ns->blkconf.blk);
+ aio_context_acquire(old_context);
+ ret = blk_set_aio_context(ns->blkconf.blk, ctx, errp);
+ aio_context_release(old_context);
+
+ if (ret) {
+ error_setg(errp, "Set AioContext on BlockBackend failed");
+ return ret;
+ }
+
+
return 0;
}
@@ -482,13 +495,13 @@ static int nvme_ns_check_constraints(NvmeNamespace *ns,
Error **errp)
return 0;
}
-int nvme_ns_setup(NvmeNamespace *ns, Error **errp)
+int nvme_ns_setup(NvmeNamespace *ns, AioContext *ctx, Error **errp)
{
if (nvme_ns_check_constraints(ns, errp)) {
return -1;
}
- if (nvme_ns_init_blk(ns, errp)) {
+ if (nvme_ns_init_blk(ns, ctx, errp)) {
return -1;
}
@@ -563,7 +576,7 @@ static void nvme_ns_realize(DeviceState *dev, Error **errp)
}
}
- if (nvme_ns_setup(ns, errp)) {
+ if (nvme_ns_setup(ns, n->ctx, errp)) {
return;
}
diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h
index b0b986b024..224b73e6c4 100644
--- a/hw/nvme/nvme.h
+++ b/hw/nvme/nvme.h
@@ -22,6 +22,7 @@
#include "hw/pci/pci.h"
#include "hw/pci/msi.h"
#include "hw/block/block.h"
+#include "sysemu/iothread.h"
#include "block/nvme.h"
@@ -276,7 +277,7 @@ static inline void nvme_aor_dec_active(NvmeNamespace *ns)
}
void nvme_ns_init_format(NvmeNamespace *ns);
-int nvme_ns_setup(NvmeNamespace *ns, Error **errp);
+int nvme_ns_setup(NvmeNamespace *ns, AioContext *ctx, Error **errp);
void nvme_ns_drain(NvmeNamespace *ns);
void nvme_ns_shutdown(NvmeNamespace *ns);
void nvme_ns_cleanup(NvmeNamespace *ns);
@@ -433,6 +434,7 @@ typedef struct NvmeParams {
uint16_t sriov_vi_flexible;
uint8_t sriov_max_vq_per_vf;
uint8_t sriov_max_vi_per_vf;
+ IOThread *iothread;
} NvmeParams;
typedef struct NvmeCtrl {
@@ -464,6 +466,8 @@ typedef struct NvmeCtrl {
uint64_t dbbuf_dbs;
uint64_t dbbuf_eis;
bool dbbuf_enabled;
+ IOThread *iothread;
+ AioContext *ctx;
struct {
MemoryRegion mem;
--
2.25.1
