Re: [PATCH] SCSI: don't get target/host busy_count in scsi_mq_get_budget()

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 11/03/2017 07:55 PM, Ming Lei wrote:
> It is very expensive to atomic_inc/atomic_dec the host wide counter of
> host->busy_count, and it should have been avoided via blk-mq's mechanism
> of getting driver tag, which uses the more efficient way of sbitmap queue.
> 
> Also we don't check atomic_read(&sdev->device_busy) in scsi_mq_get_budget()
> and don't run queue if the counter becomes zero, so IO hang may be caused
> if all requests are completed just before the current SCSI device
> is added to shost->starved_list.

This looks like an improvement. I have added it for 4.15.

Bart, does this fix your hang?

-- 
Jens Axboe




[Index of Archives]     [Linux RAID]     [Linux SCSI]     [Linux ATA RAID]     [IDE]     [Linux Wireless]     [Linux Kernel]     [ATH6KL]     [Linux Bluetooth]     [Linux Netdev]     [Kernel Newbies]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Device Mapper]

  Powered by Linux