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 | 80 ++++++++++++++++++++++++++++++++++++++++++++++----
hw/nvme/ns.c | 19 +++++++++---
hw/nvme/nvme.h | 6 +++-
3 files changed, 95 insertions(+), 10 deletions(-)
diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
index 533ad14e7a..a4efc97b33 100644
--- a/hw/nvme/ctrl.c
+++ b/hw/nvme/ctrl.c
@@ -4257,6 +4257,7 @@ static int nvme_init_cq_ioeventfd(NvmeCQueue *cq)
{
NvmeCtrl *n = cq->ctrl;
uint16_t offset = (cq->cqid << 3) + (1 << 2);
+ bool in_iothread = !qemu_in_main_thread();
int ret;
ret = event_notifier_init(&cq->notifier, 0);
@@ -4264,10 +4265,19 @@ static int nvme_init_cq_ioeventfd(NvmeCQueue *cq)
return ret;
}
- event_notifier_set_handler(&cq->notifier, nvme_cq_notifier);
+ if (in_iothread) {
+ qemu_mutex_lock_iothread();
+ }
+
+ aio_set_event_notifier(n->ctx, &cq->notifier, true, nvme_cq_notifier,
+ NULL, NULL);
memory_region_add_eventfd(&n->iomem,
0x1000 + offset, 4, false, 0, &cq->notifier);
+ if (in_iothread) {
+ qemu_mutex_unlock_iothread();
+ }
+
return 0;
}
@@ -4284,6 +4294,7 @@ static int nvme_init_sq_ioeventfd(NvmeSQueue *sq)
{
NvmeCtrl *n = sq->ctrl;
uint16_t offset = sq->sqid << 3;
+ bool in_iothread = !qemu_in_main_thread();
int ret;
ret = event_notifier_init(&sq->notifier, 0);
@@ -4291,9 +4302,16 @@ static int nvme_init_sq_ioeventfd(NvmeSQueue *sq)
return ret;
}
- event_notifier_set_handler(&sq->notifier, nvme_sq_notifier);
+ if (in_iothread) {
+ qemu_mutex_lock_iothread();
+ }
+ aio_set_event_notifier(n->ctx, &sq->notifier, true, nvme_sq_notifier,
+ NULL, NULL);
memory_region_add_eventfd(&n->iomem,
0x1000 + offset, 4, false, 0, &sq->notifier);
+ if (in_iothread) {
+ qemu_mutex_unlock_iothread();
+ }
return 0;
}
@@ -4301,13 +4319,22 @@ static int nvme_init_sq_ioeventfd(NvmeSQueue *sq)
static void nvme_free_sq(NvmeSQueue *sq, NvmeCtrl *n)
{
uint16_t offset = sq->sqid << 3;
+ bool in_iothread = !qemu_in_main_thread();
n->sq[sq->sqid] = NULL;
timer_free(sq->timer);
if (sq->ioeventfd_enabled) {
+ if (in_iothread) {
+ qemu_mutex_lock_iothread();
+ }
+
memory_region_del_eventfd(&n->iomem,
0x1000 + offset, 4, false, 0, &sq->notifier);
event_notifier_cleanup(&sq->notifier);
+
+ if (in_iothread) {
+ qemu_mutex_unlock_iothread();
+ }
}
g_free(sq->io_req);
if (sq->sqid) {
@@ -4376,8 +4403,9 @@ 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);
+ sq->timer = aio_timer_new(n->ctx, QEMU_CLOCK_VIRTUAL, SCALE_NS,
+ nvme_process_sq, sq);
if (n->dbbuf_enabled) {
sq->db_addr = n->dbbuf_dbs + (sqid << 3);
sq->ei_addr = n->dbbuf_eis + (sqid << 3);
@@ -4691,13 +4719,22 @@ static uint16_t nvme_get_log(NvmeCtrl *n, NvmeRequest
*req)
static void nvme_free_cq(NvmeCQueue *cq, NvmeCtrl *n)
{
uint16_t offset = (cq->cqid << 3) + (1 << 2);
+ bool in_iothread = !qemu_in_main_thread();
n->cq[cq->cqid] = NULL;
timer_free(cq->timer);
if (cq->ioeventfd_enabled) {
+ if (in_iothread) {
+ qemu_mutex_lock_iothread();
+ }
+
memory_region_del_eventfd(&n->iomem,
0x1000 + offset, 4, false, 0, &cq->notifier);
event_notifier_cleanup(&cq->notifier);
+
+ if (in_iothread) {
+ qemu_mutex_unlock_iothread();
+ }
}
if (msix_enabled(&n->parent_obj)) {
msix_vector_unuse(&n->parent_obj, cq->vector);
@@ -4765,7 +4802,8 @@ 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);
+ cq->timer = aio_timer_new(n->ctx, QEMU_CLOCK_VIRTUAL, SCALE_NS,
+ nvme_post_cqes, cq);
}
static uint16_t nvme_create_cq(NvmeCtrl *n, NvmeRequest *req)
@@ -6557,6 +6595,7 @@ static void nvme_write_bar(NvmeCtrl *n, hwaddr offset,
uint64_t data,
uint32_t intms = ldl_le_p(&n->bar.intms);
uint32_t csts = ldl_le_p(&n->bar.csts);
uint32_t pmrsts = ldl_le_p(&n->bar.pmrsts);
+ bool in_iothread = !qemu_in_main_thread();
if (unlikely(offset & (sizeof(uint32_t) - 1))) {
NVME_GUEST_ERR(pci_nvme_ub_mmiowr_misaligned32,
@@ -6726,10 +6765,22 @@ static void nvme_write_bar(NvmeCtrl *n, hwaddr offset,
uint64_t data,
stl_le_p(&n->bar.pmrctl, data);
if (NVME_PMRCTL_EN(data)) {
+ if (in_iothread) {
+ qemu_mutex_lock_iothread();
+ }
memory_region_set_enabled(&n->pmr.dev->mr, true);
+ if (in_iothread) {
+ qemu_mutex_unlock_iothread();
+ }
pmrsts = 0;
} else {
+ if (in_iothread) {
+ qemu_mutex_lock_iothread();
+ }
memory_region_set_enabled(&n->pmr.dev->mr, false);
+ if (in_iothread) {
+ qemu_mutex_unlock_iothread();
+ }
NVME_PMRSTS_SET_NRDY(pmrsts, 1);
n->pmr.cmse = false;
}
@@ -7528,6 +7579,14 @@ 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)
@@ -7600,7 +7659,7 @@ 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(n, ns, errp)) {
return;
}
@@ -7631,6 +7690,15 @@ 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);
}
@@ -7665,6 +7733,8 @@ static Property nvme_props[] = {
DEFINE_PROP_BOOL("use-intel-id", NvmeCtrl, params.use_intel_id, false),
DEFINE_PROP_BOOL("legacy-cmb", NvmeCtrl, params.legacy_cmb, false),
DEFINE_PROP_BOOL("ioeventfd", NvmeCtrl, params.ioeventfd, true),
+ DEFINE_PROP_LINK("iothread", NvmeCtrl, params.iothread, TYPE_IOTHREAD,
+ IOThread *),
DEFINE_PROP_UINT8("zoned.zasl", NvmeCtrl, params.zasl, 0),
DEFINE_PROP_BOOL("zoned.auto_transition", NvmeCtrl,
params.auto_transition_zones, true),
diff --git a/hw/nvme/ns.c b/hw/nvme/ns.c
index 62a1f97be0..683d0d7a3b 100644
--- a/hw/nvme/ns.c
+++ b/hw/nvme/ns.c
@@ -146,8 +146,10 @@ lbaf_found:
return 0;
}
-static int nvme_ns_init_blk(NvmeNamespace *ns, Error **errp)
+static int nvme_ns_init_blk(NvmeCtrl *n, NvmeNamespace *ns, Error **errp)
{
+ AioContext *old_context;
+ int ret;
bool read_only;
if (!blkconf_blocksizes(&ns->blkconf, errp)) {
@@ -170,6 +172,15 @@ 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, n->ctx, errp);
+ aio_context_release(old_context);
+
+ if (ret) {
+ error_setg(errp, "Set AioContext on BlockBackend failed");
+ }
+
return 0;
}
@@ -482,13 +493,13 @@ static int nvme_ns_check_constraints(NvmeNamespace *ns,
Error **errp)
return 0;
}
-int nvme_ns_setup(NvmeNamespace *ns, Error **errp)
+int nvme_ns_setup(NvmeCtrl *n, NvmeNamespace *ns, Error **errp)
{
if (nvme_ns_check_constraints(ns, errp)) {
return -1;
}
- if (nvme_ns_init_blk(ns, errp)) {
+ if (nvme_ns_init_blk(n, ns, errp)) {
return -1;
}
@@ -563,7 +574,7 @@ static void nvme_ns_realize(DeviceState *dev, Error **errp)
}
}
- if (nvme_ns_setup(ns, errp)) {
+ if (nvme_ns_setup(n, ns, errp)) {
return;
}
diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h
index 79f5c281c2..85e2aa7b29 100644
--- a/hw/nvme/nvme.h
+++ b/hw/nvme/nvme.h
@@ -21,6 +21,7 @@
#include "qemu/uuid.h"
#include "hw/pci/pci.h"
#include "hw/block/block.h"
+#include "sysemu/iothread.h"
#include "block/nvme.h"
@@ -275,7 +276,7 @@ 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(NvmeCtrl *n, NvmeNamespace *ns, Error **errp);
void nvme_ns_drain(NvmeNamespace *ns);
void nvme_ns_shutdown(NvmeNamespace *ns);
void nvme_ns_cleanup(NvmeNamespace *ns);
@@ -427,6 +428,7 @@ 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 {
@@ -458,6 +460,8 @@ typedef struct NvmeCtrl {
uint64_t dbbuf_dbs;
uint64_t dbbuf_eis;
bool dbbuf_enabled;
+ IOThread *iothread;
+ AioContext *ctx;
struct {
MemoryRegion mem;
--
2.25.1
