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| author | Oleksij Rempel <[email protected]> | 2016-04-26 08:27:46 +0200 |
|---|---|---|
| committer | Wolfram Sang <[email protected]> | 2016-04-26 23:34:09 +0200 |
| commit | 2b899f34e1db9adef8716d07e872a800dfa60790 (patch) | |
| tree | 6de5190c4e2042cf1fc4522d25f0e8398bfb0f46 /fs/jbd2/commit.c | |
| parent | 1bb1ff3e7c74f4569dddf7bda8054a0bb6ed0073 (diff) | |
i2c: imx: reduce load by using usleep_range instead of udelay
Documentation/timers/timers-howto.txt recommends to use
usleep_range on delays > 10usec. According to my test results
with Neonode zForce touchscreen driver, usleep_range indeed
reduces CPU load.
Stats collected with "./perf record -a -g -F 1000 sleep 10"
i2c-imx with udelay(50):
34.19% 0.00% irq/220-Neonode [kernel.kallsyms] [k] irq_thread
---irq_thread
|--33.75%--irq_thread_fn
| |--19.27%--0x7f08a878
| | i2c_master_recv
| | i2c_transfer
| | __i2c_transfer
| | i2c_imx_xfer
| | |--11.71%--i2c_imx_trx_complete
| | |--5.70%--i2c_imx_start <<<<----------------
| | | |--5.38%--__timer_const_udelay
| | | | __timer_delay
| | | | --5.07%--read_current_timer
i2c-imx with usleep_range(50,100)
29.08% 0.00% irq/220-Neonode [kernel.kallsyms] [k] irq_thread
---irq_thread
|--28.89%--irq_thread_fn
| |--17.21%--0x7f08a878
| | i2c_master_recv
| | |--17.14%--i2c_transfer
| | | __i2c_transfer
| | | i2c_imx_xfer
| | | |--14.29%--i2c_imx_trx_complete
| | | |--1.42%--i2c_imx_start <<<<----------
| | | | |--0.71%--usleep_range
| | | | |--0.53%--i2c_imx_bus_busy
Signed-off-by: Oleksij Rempel <[email protected]>
Signed-off-by: Dirk Behme <[email protected]>
Reviewed-by: Vladimir Zapolskiy <[email protected]>
Signed-off-by: Wolfram Sang <[email protected]>
Diffstat (limited to 'fs/jbd2/commit.c')
0 files changed, 0 insertions, 0 deletions