On 11/14/2016 11:11 AM, Christoph Hellwig wrote:
On Mon, Nov 14, 2016 at 11:08:46AM -0700, Jens Axboe wrote:
It'd be cleaner to loop one level out, and avoid all that 'dio' stuff
instead. And then still retain the separate parts of the sync and async.
There's nothing to share there imho, and it just makes the code harder
to read.
How do you avoid it for the async case? We can only call ki_complete
once all bios have finished, which means we need a tracking structure
for it. For the synchronous case we could in theory wait for the
previous bio before sending the next, but there are plenty of RAID
arrays that would prefer > 1MB I/O. And we can pretty much reuse the
async case for this anyway.
Just make the limit reasonable - with a order 1 alloc, we have 256
pages, or 1MB of IO. Loop around that. We could play tricks with bio
reuse and using the ref count for knowing when it'd be done.
--
Jens Axboe
--
To unsubscribe from this list: send the line "unsubscribe linux-block" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
