Re: [RFC] blk-mq and I/O scheduling

2015-11-30 Thread Andreas Herrmann
On Wed, Nov 25, 2015 at 12:47:21PM -0700, Jens Axboe wrote: > On 11/19/2015 05:02 AM, Andreas Herrmann wrote: --8<-- > >The latter helped to improve performance for sequential reads and > >writes. But it's not on a par with CFQ. Increasing the time slice is > >suboptimal (as shown with the 2ms

Re: [RFC] blk-mq and I/O scheduling

2015-11-30 Thread Andreas Herrmann
On Tue, Nov 24, 2015 at 09:19:32AM +0100, Christoph Hellwig wrote: > Hi Andreas, Hi Christoph, > I don't understand the time slicing algorithm to well, but from the > blk-mq integration perspective this looks nice, and anything that > helps improving blk-mq for spinning rust is useful. I'll put

Re: [RFC] blk-mq and I/O scheduling

2015-11-30 Thread Andreas Herrmann
On Wed, Nov 25, 2015 at 12:47:21PM -0700, Jens Axboe wrote: > On 11/19/2015 05:02 AM, Andreas Herrmann wrote: --8<-- > >The latter helped to improve performance for sequential reads and > >writes. But it's not on a par with CFQ. Increasing the time slice is > >suboptimal (as shown with the 2ms

Re: [RFC] blk-mq and I/O scheduling

2015-11-30 Thread Andreas Herrmann
On Tue, Nov 24, 2015 at 09:19:32AM +0100, Christoph Hellwig wrote: > Hi Andreas, Hi Christoph, > I don't understand the time slicing algorithm to well, but from the > blk-mq integration perspective this looks nice, and anything that > helps improving blk-mq for spinning rust is useful. I'll put

Re: [RFC] blk-mq and I/O scheduling

2015-11-25 Thread Jens Axboe
On 11/19/2015 05:02 AM, Andreas Herrmann wrote: Hi, I've looked into blk-mq and possible support for I/O scheduling. The reason for this is to minimize performance degradation with rotational devices when scsi_mod.use_blk_mq=1 is switched on. I think that the degradation is well reflected

Re: [RFC] blk-mq and I/O scheduling

2015-11-25 Thread Jens Axboe
On 11/19/2015 05:02 AM, Andreas Herrmann wrote: Hi, I've looked into blk-mq and possible support for I/O scheduling. The reason for this is to minimize performance degradation with rotational devices when scsi_mod.use_blk_mq=1 is switched on. I think that the degradation is well reflected

Re: [RFC] blk-mq and I/O scheduling

2015-11-24 Thread Christoph Hellwig
Hi Andreas, I don't understand the time slicing algorithm to well, but from the blk-mq integration perspective this looks nice, and anything that helps improving blk-mq for spinning rust is useful. As a nitpick some of the larger "if (use_time_slice)" blocks should be moved into separate helper

Re: [RFC] blk-mq and I/O scheduling

2015-11-24 Thread Christoph Hellwig
Hi Andreas, I don't understand the time slicing algorithm to well, but from the blk-mq integration perspective this looks nice, and anything that helps improving blk-mq for spinning rust is useful. As a nitpick some of the larger "if (use_time_slice)" blocks should be moved into separate helper

[RFC] blk-mq and I/O scheduling

2015-11-19 Thread Andreas Herrmann
Hi, I've looked into blk-mq and possible support for I/O scheduling. The reason for this is to minimize performance degradation with rotational devices when scsi_mod.use_blk_mq=1 is switched on. I think that the degradation is well reflected with fio measurements. With an increasing number of

[RFC] blk-mq and I/O scheduling

2015-11-19 Thread Andreas Herrmann
Hi, I've looked into blk-mq and possible support for I/O scheduling. The reason for this is to minimize performance degradation with rotational devices when scsi_mod.use_blk_mq=1 is switched on. I think that the degradation is well reflected with fio measurements. With an increasing number of