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edd63fcc97
Unnecessarily mapping and unmapping the align buffer for SD cards is expensive: performance measurements on iMX6 show that this gives a hit of 10% on hdparm buffered disk reads. MMC/SD card IO comes from the mm/vfs which gives us page based IO, so for this case, the align buffer is not going to be used. However, we still map and unmap this buffer. Eliminate this by switching the align buffer to be a DMA coherent buffer, which needs no DMA maintenance to access the buffer. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Cc: stable@vger.kernel.org # v4.5+ Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> |
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