> > On 5/24/2021 1:10 PM, Bart Van Assche wrote: > > > On 5/24/21 1:36 AM, Can Guo wrote: > > >> Current UFS IRQ handler is completely wrapped by host lock, and > because > > >> ufshcd_send_command() is also protected by host lock, when IRQ > handler > > >> fires, not only the CPU running the IRQ handler cannot send new > > requests, > > >> the rest CPUs can neither. Move the host lock wrapping the IRQ handler > > into > > >> specific branches, i.e., ufshcd_uic_cmd_compl(), ufshcd_check_errors(), > > >> ufshcd_tmc_handler() and ufshcd_transfer_req_compl(). Meanwhile, to > > further > > >> reduce occpuation of host lock in ufshcd_transfer_req_compl(), host > lock > > is > > >> no longer required to call __ufshcd_transfer_req_compl(). As per test, > the > > >> optimization can bring considerable gain to random read/write > > performance. > > > > > > > > An additional question is whether it is necessary for v3.0 UFS devices > > > to serialize the submission path against the completion path? Multiple > > > high-performance SCSI LLDs support hardware with separate submission > > and > > > completion queues and hence do not need any serialization between the > > > submission and the completion path. I'm asking this because it is likely > > > that sooner or later multiqueue support will be added in the UFS > > > specification. Benefiting from multiqueue support will require to rework > > > locking in the UFS driver anyway. > > > > > Hi Bart, > > No it's not necessary to serialize both the paths. I think this series > > attempts to remove this serialization to a certain degree, which is > > what's giving the performance improvement. Btw, Is this performance improvement is on top of rq_affinity 2 or 1? Thanks, Avri > > > > Even if multiqueue support would be available in the future, I think > > this change is apt now for the current available specification. > I agree - this looks like the harbinger of a major change, > And going further with respect of hw queues, > will need the spec support - e.g. doorbell per lane, etc. > > Thanks, > Avri > > > > Thanks, > > > > > > Bart. > > > > > > > > > Thanks, > > -asd > > > > -- > > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora > > Forum, > > Linux Foundation Collaborative Project
