Re: [PATCH 46/49] xfs: Combine CIL insert and prepare passes

Mark Tinguely
2013-07-29T21:07:28Z

On 07/19/13 01:25, Dave Chinner wrote:
> From: Dave Chinner<dchinner@redhat.com>
>
> Now that all the log item preparation and formatting is done under
> the CIL lock, we can get rid of the intermediate log vector chain
> used to track items to be inserted into the CIL.
>
> We can already find all the items to be committed from the
> transaction handle, so as long as we attach the log vectors to the
> item before we insert the items into the CIL, we don't need to
> create a log vector chain to pass around.
>
> This means we can move all the item insertion code into and optimise
> it into a pair of simple passes across all the items in the
> transaction. The first pass does the formatting and accounting, the
> second inserts them all into the CIL.
>
> We keep this two pass split so that we can separate the CIL
> insertion - which must be done under the CIL spinlock - from the
> formatting. We could insert each item into the CIL with a single
> pass, but that massively increases the number of times we have to
> grab the CIL spinlock. It is much more efficient (and hence
> scalable) to do a batch operation and insert all objects in a single
> lock grab.
>
> Signed-off-by: Dave Chinner<dchinner@redhat.com>
> ---

Removed the old log commit vector chain interface.

Looks good. Still like the additional assert for cil space stealing.

Reviewed-by: Mark Tinguely <tinguely@sgi.com>