Squashfs: Add an option to set dev block size to 4K

[pandora-kernel.git] / fs / squashfs / Kconfig

diff --git a/fs/squashfs/Kconfig b/fs/squashfs/Kconfig
index 1360d4f..5586011 100644 (file)
--- a/fs/squashfs/Kconfig
+++ b/fs/squashfs/Kconfig
@@ -78,6 +78,28 @@ config SQUASHFS_XZ
 
          If unsure, say N.
 
+config SQUASHFS_4K_DEVBLK_SIZE
+       bool "Use 4K device block size?"
+       depends on SQUASHFS
+       help
+         By default Squashfs sets the dev block size (sb_min_blocksize)
+         to 1K or the smallest block size supported by the block device
+         (if larger).  This, because blocks are packed together and
+         unaligned in Squashfs, should reduce latency.
+
+         This, however, gives poor performance on MTD NAND devices where
+         the optimal I/O size is 4K (even though the devices can support
+         smaller block sizes).
+
+         Using a 4K device block size may also improve overall I/O
+         performance for some file access patterns (e.g. sequential
+         accesses of files in filesystem order) on all media.
+
+         Setting this option will force Squashfs to use a 4K device block
+         size by default.
+
+         If unsure, say N.
+
 config SQUASHFS_EMBEDDED
        bool "Additional option for memory-constrained systems"
        depends on SQUASHFS