On 01/19/2012 09:19 PM, qiang....@freescale.com wrote:
From: Qiang Liu<qiang....@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....@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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