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Add a block device cache to speed up repeated reads of block devices by
various filesystems.
This small amount of cache can dramatically speed up filesystem
operations by skipping repeated reads of common areas of a block
device (typically directory structures).
This has shown to have some benefit on FAT filesystem operations of
loading a kernel and RAM disk, but more dramatic benefits on ext4
filesystems when the kernel and/or RAM disk are spread across
multiple extent header structures as described in commit fc0fc50.
The cache is implemented through a minimal list (block_cache) maintained
in most-recently-used order and count of the current number of entries
(cache_count). It uses a maximum block count setting to prevent copies
of large block reads and an upper bound on the number of cached areas.
The maximum number of entries in the cache defaults to 32 and the maximum
number of blocks per cache entry has a default of 2, which has shown to
produce the best results on testing of ext4 and FAT filesystems.
The 'blkcache' command (enabled through CONFIG_CMD_BLOCK_CACHE) allows
changing these values and can be used to tune for a particular filesystem
layout.
Signed-off-by: Eric Nelson <[email protected]>
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Add a uclass for block devices. These provide block-oriented data access,
supporting reading, writing and erasing of whole blocks.
Signed-off-by: Simon Glass <[email protected]>
Reviewed-by: Bin Meng <[email protected]>
Tested-by: Stephen Warren <[email protected]>
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To ease conversion to driver model, add helper functions which deal with
calling each block device method. With driver model we can reimplement these
functions with the same arguments.
Use inline functions to avoid increasing code size on some boards.
Signed-off-by: Simon Glass <[email protected]>
Reviewed-by: Bin Meng <[email protected]>
Tested-by: Stephen Warren <[email protected]>
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This is a device number, and we want to use 'dev' to mean a driver model
device. Rename the member.
Signed-off-by: Simon Glass <[email protected]>
Reviewed-by: Bin Meng <[email protected]>
Tested-by: Stephen Warren <[email protected]>
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Since these are sequentially numbered it makes sense to use an enum. It
avoids having to maintain the maximum value, and provides a type we can use
if it is useful.
In fact the maximum value is not used. Rename it to COUNT, since MAX suggests
it is the maximum valid value, but it is not.
Signed-off-by: Simon Glass <[email protected]>
Tested-by: Stephen Warren <[email protected]>
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At present block devices are tied up with partitions. But not all block
devices have partitions within them. They are in fact separate concepts.
Create a separate blk.h header file for block devices.
Signed-off-by: Simon Glass <[email protected]>
Reviewed-by: Bin Meng <[email protected]>
Tested-by: Stephen Warren <[email protected]>
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