Re: [PATCH] as-iosched: fix write batch start point

[Nick Piggin <npiggin@suse.de>]

On Wed, Dec 05, 2007 at 09:07:07PM +1100, Aaron Carroll wrote:
> New write batches currently start from where the last one completed.
> We have no idea where the head is after switching batches, so this
> makes little sense.  Instead, start the next batch from the request
> with the earliest deadline in the hope that we avoid a deadline
> expiry later on.
> 
> Signed-off-by: Aaron Carroll <aaronc@gelato.unsw.edu.au>

I think this seems reasonable. What's deadline doing in this case?
They should probably be kept in synch where possible...

Acked-by: Nick Piggin <npiggin@suse.de>

> ---
>  block/as-iosched.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/block/as-iosched.c b/block/as-iosched.c
> index 4513fc5..555cd6b 100644
> --- a/block/as-iosched.c
> +++ b/block/as-iosched.c
> @@ -1097,7 +1097,8 @@ dispatch_writes:
>  		ad->batch_data_dir = REQ_ASYNC;
>  		ad->current_write_count = ad->write_batch_count;
>  		ad->write_batch_idled = 0;
> -		rq = ad->next_rq[ad->batch_data_dir];
> +		rq = rq_entry_fifo(ad->fifo_list[REQ_ASYNC].next);
> +		ad->last_check_fifo[REQ_ASYNC] = jiffies;
>  		goto dispatch_request;
>  	}
>  
> --