On Thu, 17 Aug 2023 14:29:02 -0500, Mike Christie wrote:
> The write back throttling (WBT) code checks if REQ_SYNC | REQ_IDLE is set
> to determine if a write is O_DIRECT vs buffered. If the bits are not set
> then it assumes it's a buffered write and will throttle LIO if we hit
> certain metrics. LIO itself is not using the buffer cache and is doing
> direct IO, so this has us set the direct bits so we are not throttled.
>
> When the initiator application is doing direct IO this can greatly
> improve performance. It depends on the backend device but we have seen
> where the WBT code is throttling writes to only 20K IOPs with 4K IOs when
> the device can support 100K+.
>
> [...]
Applied to 6.6/scsi-queue, thanks!
[1/1] scsi: target: Fix write perf due to unneeded throttling
https://git.kernel.org/mkp/scsi/c/84c073fd89de
--
Martin K. Petersen Oracle Linux Engineering
