[PATCH V2] fsl-sata: I/O load balancing

[Liu Qiang-B32616]

> -----Original Message-----
> From: linux-ide-owner at vger.kernel.org [mailto:linux-ide-
> owner at vger.kernel.org] On Behalf Of Jeff Garzik
> Sent: Saturday, February 11, 2012 2:26 AM
> To: Liu Qiang-B32616
> Cc: linux-ide at vger.kernel.org; linux-kernel at vger.kernel.org; linuxppc-
> dev at lists.ozlabs.org
> Subject: Re: [PATCH V2] fsl-sata: I/O load balancing
> 
> On 01/19/2012 09:19 PM, qiang.liu at freescale.com wrote:
> > From: Qiang Liu<qiang.liu at freescale.com>
> >
> > Reduce interrupt signals through reset Interrupt Coalescing Control Reg.
> > Provide dynamic method to adjust interrupt signals and timer ticks by
> sysfs.
> > It is a tradeoff for different applications.
> >
> > Signed-off-by: Qiang Liu<qiang.liu at freescale.com>
> > ---
> >
> > change for V2
> > 	support dynamic config interrupt coalescing register by /sysfs
> > 	test random small file with iometer
> > Description:
> >    1. fsl-sata interrupt will be raised 130 thousand times when write
> 8G file
> >      (dd if=/dev/zero of=/dev/sda2 bs=128K count=65536);
> >    2. most of interrupts raised because of only 1-4 commands completed;
> >    3. only 30 thousand times will be raised after set max interrupt
> threshold,
> >      more interrupts are coalesced as the description of ICC;
> >
> > Test methods and results:
> >    1. test sequential large file performance,
> >    [root at p2020ds root]# echo 31 524287>  \
> >    	/sys/devices/soc.0/ffe18000.sata/intr_coalescing
> >    [root at p2020ds root]# dd if=/dev/zero of=/dev/sda2 bs=128K
> count=65536&
> >    [root at p2020ds root]# top
> >
> >    CPU %  |  dd   |  flush-8:0 | softirq
> >    ---------------------------------------
> >    before | 20-22 |    17-19   |    7
> >    ---------------------------------------
> >    after  | 18-21 |    15-16   |    5
> >    ---------------------------------------
> >    2. test random small file with iometer,
> >   iometer paramters:
> >     4 I/Os burst length, 1MB transfer request size, 100% write, 2MB
> file size
> >     as default configuration of interrupt coalescing register, 1
> interrupts and
> >   no timeout config, total write performance is 119MB per second,
> >     after config with the maximum value, write performance is 110MB per
> second.
> >
> >    After compare the test results, a configuable interrupt coalescing
> should be
> >    better when cope with flexible context.
> >
> >   drivers/ata/sata_fsl.c |  111
> ++++++++++++++++++++++++++++++++++++++++++++++--
> >   1 files changed, 107 insertions(+), 4 deletions(-)
> 
> Doesn't seem to apply to upstream, or another less recent -rc...
Thanks, I will resend it latterly.
> 
> 	Jeff
> 
> 
> 
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