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| author | Pierre Ossman <drzeus@drzeus.cx> | 2007-05-12 00:26:16 +0200 |
|---|---|---|
| committer | Pierre Ossman <drzeus@drzeus.cx> | 2007-07-09 21:22:53 +0200 |
| commit | 98ccf14909ba02a41c5925b0b2c92aeeef23d3b9 (patch) | |
| tree | 331b645ee008f858305f7406f4639119b275ff82 /drivers/mmc/card/Kconfig | |
| parent | 7dcca30a32aadb0520417521b0c44f42d09fe05c (diff) | |
| download | kernel_samsung_aries-98ccf14909ba02a41c5925b0b2c92aeeef23d3b9.zip kernel_samsung_aries-98ccf14909ba02a41c5925b0b2c92aeeef23d3b9.tar.gz kernel_samsung_aries-98ccf14909ba02a41c5925b0b2c92aeeef23d3b9.tar.bz2 | |
mmc: bounce requests for simple hosts
Some hosts cannot do scatter/gather in hardware. Since not doing sg
is such a big performance hit, we (optionally) bounce the requests
to a simple linear buffer that we hand over to the driver.
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
Diffstat (limited to 'drivers/mmc/card/Kconfig')
| -rw-r--r-- | drivers/mmc/card/Kconfig | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/mmc/card/Kconfig b/drivers/mmc/card/Kconfig index 9320a8c..a49cb97 100644 --- a/drivers/mmc/card/Kconfig +++ b/drivers/mmc/card/Kconfig @@ -14,3 +14,21 @@ config MMC_BLOCK mount the filesystem. Almost everyone wishing MMC support should say Y or M here. +config MMC_BLOCK_BOUNCE + bool "Use bounce buffer for simple hosts" + depends on MMC_BLOCK + default y + help + SD/MMC is a high latency protocol where it is crucial to + send large requests in order to get high performance. Many + controllers, however, are restricted to continuous memory + (i.e. they can't do scatter-gather), something the kernel + rarely can provide. + + Say Y here to help these restricted hosts by bouncing + requests back and forth from a large buffer. You will get + a big performance gain at the cost of up to 64 KiB of + physical memory. + + If unsure, say Y here. + |