On 09/06/2018 09:07 PM, Ming Lei wrote: > On Thu, Sep 06, 2018 at 09:28:46AM +0800, jianchao.wang wrote: >> Hi Ming >> >> On 09/06/2018 06:09 AM, Ming Lei wrote: >>> nvme_dev_add() still may call freeze & unfreeze queue, so your patch >>> can't avoid draining queue completely here. >> >> Yes, I know this. We still need to freeze queue when update nr_hw_queues. >> But we move forward a step at least. :) >> We don't need to drain request queue in normal case of nvme_reset_work. > > It is hard to say who is the normal case. In case of CPU hotplug, it is quite > easy to trigger updating nr_hw_queues. > >> >> As for updating nr_hw_queues, we could try some other method on it next. > > The thing is that draining queue may be inevitable inside reset work > function because of updating nr_hw_queues, that means the approach in > this patchset is just a partial solution > > Or it may not make sense to do that because we may never remove the draining > queue in the code path of updating nr_hw_queues. > > Given they belong to same issue, I suggest to solve them all. I still think if just prevent new IO, freeze queue is over-kill. With respect to update nr_hw_queues, we could try to take the bios down from the queued requests as the blk_steal_bios. Then re-issue these bios after updating the nr_hw_queues. Thanks Jianchao > > Thanks, > Ming > > _______________________________________________ > Linux-nvme mailing list > Linux-nvme@xxxxxxxxxxxxxxxxxxx > https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.infradead.org_mailman_listinfo_linux-2Dnvme&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=7WdAxUBeiTUTCy8v-7zXyr4qk7sx26ATvfo6QSTvZyQ&m=cybJ83konrbKh9jtodiaZRmNrKAo1YtEI_oyaNIbuvk&s=EBhkv_XTOQb3K3-4esnkBrs_ErKuNzXDqZwrIzEA0ig&e= >
