Re: [PATCH] hw/nvme: add trace events for ioeventfd

[Jinhao Fan]

at 10:41 PM, Jinhao Fan <fanjinhao21s@ict.ac.cn> wrote:

> at 1:34 PM, Klaus Jensen <its@irrelevant.dk> wrote:
> 
>> From: Klaus Jensen <k.jensen@samsung.com>
>> 
>> While testing Jinhaos ioeventfd patch I found it useful with a couple of
>> additional trace events since we no longer see the mmio events.
>> 
>> Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
>> ---
>> hw/nvme/ctrl.c       | 8 ++++++++
>> hw/nvme/trace-events | 4 ++++
>> 2 files changed, 12 insertions(+)
>> 
>> diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
>> index 533ad14e7a61..09725ec49c5d 100644
>> --- a/hw/nvme/ctrl.c
>> +++ b/hw/nvme/ctrl.c
>> @@ -1346,6 +1346,8 @@ static void nvme_post_cqes(void *opaque)
>>    bool pending = cq->head != cq->tail;
>>    int ret;
>> 
>> +    trace_pci_nvme_post_cqes(cq->cqid);
>> +
>>    QTAILQ_FOREACH_SAFE(req, &cq->req_list, entry, next) {
>>        NvmeSQueue *sq;
>>        hwaddr addr;
>> @@ -4238,6 +4240,8 @@ static void nvme_cq_notifier(EventNotifier *e)
>>    NvmeCQueue *cq = container_of(e, NvmeCQueue, notifier);
>>    NvmeCtrl *n = cq->ctrl;
>> 
>> +    trace_pci_nvme_cq_notify(cq->cqid);
>> +
>>    event_notifier_test_and_clear(&cq->notifier);
>> 
>>    nvme_update_cq_head(cq);
>> @@ -4275,6 +4279,8 @@ static void nvme_sq_notifier(EventNotifier *e)
>> {
>>    NvmeSQueue *sq = container_of(e, NvmeSQueue, notifier);
>> 
>> +    trace_pci_nvme_sq_notify(sq->sqid);
>> +
>>    event_notifier_test_and_clear(&sq->notifier);
>> 
>>    nvme_process_sq(sq);
>> @@ -6240,6 +6246,8 @@ static void nvme_process_sq(void *opaque)
>>    NvmeCtrl *n = sq->ctrl;
>>    NvmeCQueue *cq = n->cq[sq->cqid];
>> 
>> +    trace_pci_nvme_process_sq(sq->sqid);
>> +
>>    uint16_t status;
>>    hwaddr addr;
>>    NvmeCmd cmd;
>> diff --git a/hw/nvme/trace-events b/hw/nvme/trace-events
>> index fccb79f48973..45dd708bd2fa 100644
>> --- a/hw/nvme/trace-events
>> +++ b/hw/nvme/trace-events
>> @@ -104,6 +104,10 @@ pci_nvme_mmio_shutdown_set(void) "shutdown bit set"
>> pci_nvme_mmio_shutdown_cleared(void) "shutdown bit cleared"
>> pci_nvme_shadow_doorbell_cq(uint16_t cqid, uint16_t new_shadow_doorbell) 
>> "cqid %"PRIu16" new_shadow_doorbell %"PRIu16""
>> pci_nvme_shadow_doorbell_sq(uint16_t sqid, uint16_t new_shadow_doorbell) 
>> "sqid %"PRIu16" new_shadow_doorbell %"PRIu16""
>> +pci_nvme_sq_notify(uint16_t sqid) "sqid %"PRIu16""
>> +pci_nvme_cq_notify(uint16_t cqid) "cqid %"PRIu16""
>> +pci_nvme_process_sq(uint16_t sqid) "sqid %"PRIu16""
>> +pci_nvme_post_cqes(uint16_t cqid) "cqid %"PRIu16""
>> pci_nvme_open_zone(uint64_t slba, uint32_t zone_idx, int all) "open zone, 
>> slba=%"PRIu64", idx=%"PRIu32", all=%"PRIi32""
>> pci_nvme_close_zone(uint64_t slba, uint32_t zone_idx, int all) "close zone, 
>> slba=%"PRIu64", idx=%"PRIu32", all=%"PRIi32""
>> pci_nvme_finish_zone(uint64_t slba, uint32_t zone_idx, int all) "finish 
>> zone, slba=%"PRIu64", idx=%"PRIu32", all=%"PRIi32""
>> -- 
>> 2.36.1
> 
> I agree on the addition of SQ and CQ notify trace events. But what is the
> purpose for adding tracepoints for nvme_process_sq and nvme_post_cqes?

I realized these two events are useful when debugging iothread support. We
are processing sqe and cqe’s in a batch in nvme_process_sq and
nvme_post_cqes. It is important to mark the beginning of the batch.