RE: How to get more sequential IO merged at elevator

2014-05-07 Thread Kashyap Desai
> -Original Message- > From: Jens Axboe [mailto:ax...@kernel.dk] > Sent: Tuesday, May 06, 2014 7:47 PM > To: Desai, Kashyap > Cc: linux-scsi@vger.kernel.org > Subject: Re: How to get more sequential IO merged at elevator > > On 05/06/2014 04:06 AM, Desai, Kashyap wr

RE: How to get more sequential IO merged at elevator

2014-05-07 Thread Kashyap Desai
> -Original Message- > From: Jens Axboe [mailto:ax...@kernel.dk] > Sent: Tuesday, May 06, 2014 7:47 PM > To: Desai, Kashyap > Cc: linux-scsi@vger.kernel.org > Subject: Re: How to get more sequential IO merged at elevator > > On 05/06/2014 04:06 AM, Desai, Kashyap wr

Re: How to get more sequential IO merged at elevator

2014-05-06 Thread Jens Axboe
On 05/06/2014 04:06 AM, Desai, Kashyap wrote: > I got some clue on what was going on while doing 4K sequential read using fio. > > If I use ioengine in fio script as "libaio", I see " do_io_submit" call > plug/unplug the queue before submitting the IO. > It means after every IO, we expect to send

RE: How to get more sequential IO merged at elevator

2014-05-06 Thread Desai, Kashyap
I got some clue on what was going on while doing 4K sequential read using fio. If I use ioengine in fio script as "libaio", I see " do_io_submit" call plug/unplug the queue before submitting the IO. It means after every IO, we expect to send IO immediately to the next layer. If at all there are