Re: [PATCH RFC] virtio: use QUEUE_FLAG_CLUSTER in virtio_blk

[Rusty Russell <rusty@rustcorp.com.au>]

On Friday 14 November 2008 20:00:23 Jens Axboe wrote:
> Queue clustering is on by default though when you allocate your queue,
> so I'm surprised you see a difference by doing:
>
> +	/* Gather adjacent buffers to minimize sg length. */
> +	queue_flag_set(QUEUE_FLAG_CLUSTER, vblk->disk->queue);
>
> did test_bit(QUEUE_FLAG_CLUSTER, &vblk->disk->queue->queue_flags) really
> return 0 before?

Apparently not.  My results must be noise :(

However, it made me look harder at the behaviour of the driver.  I have two 
other enhancement patches while I'll send now, but I still only see sgs of 116 
elements.

Thanks for the clue donation,
Rusty.