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SubjectRe: [PATCH V2] fsl-sata: I/O load balancing
On 01/19/2012 09:19 PM, qiang.liu@freescale.com wrote:
> From: Qiang Liu<qiang.liu@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@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@p2020ds root]# echo 31 524287> \
> /sys/devices/soc.0/ffe18000.sata/intr_coalescing
> [root@p2020ds root]# dd if=/dev/zero of=/dev/sda2 bs=128K count=65536&
> [root@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...

Jeff





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