Re: IO scheduler, queue depth, nr_requests

[Andrew Morton]

Miquel van Smoorenburg <miquels@xxxxxxxxxx> wrote:
>
> The thing is, the bio's are submitted perfectly sequentially. It's just that
>  every so often a request (with just its initial bio) gets stuck for a while.
>  Because the bio's after it are merged and sent to the device, it's not
>  possible to merge that stuck request later on when it gets unstuck, because
>  the other bio's have already left the building so to speak.

Oh.  So the raid controller's queue depth is larger than the kernel's.  So
everything gets immediately shovelled into the device and the kernel is
left with nothing to merge the little request against.

Shouldn't the controller itself be performing the insertion?
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/