Re: [PATCH] scsi: sd: Contribute to randomness when running rotational device

[Theodore Y. Ts'o]

On Thu, Sep 06, 2018 at 03:27:53PM -0700, Bart Van Assche wrote:
> 
> Although this patch looks fine to me, seeing this patch makes me wonder
> whether the default should be changed (QUEUE_FLAG_MQ_DEFAULT) instead of
> modifying the sd driver. Can anyone remind me why QUEUE_FLAG_MQ_DEFAULT does
> not include QUEUE_FLAG_ADD_RANDOM?

There was a discussion about a number of *years* ago; blk-mq has been
baking for a very long time.  In the early days of block_mq, the
overwhelming percentage of the users of blk-mq where those who were
using PCIe attached flash.  So when, I raised this question, the
argument was that SSD users have no entropy.  Which I agree with; but
now that blk-mq is the default, and hard drives are using blk-mq, it's
time for a patch like Xuewei's.

Cheers,

					- Ted