Merge tag 'squashfs-updates' of git://git.kernel.org/pub/scm/linux/kernel/git/pkl...

[cascardo/linux.git] / fs / squashfs / Kconfig

diff --git a/fs/squashfs/Kconfig b/fs/squashfs/Kconfig
index 048b59d..b6fa865 100644 (file)
--- a/fs/squashfs/Kconfig
+++ b/fs/squashfs/Kconfig
@@ -25,6 +25,78 @@ config SQUASHFS
 
          If unsure, say N.
 
+choice
+       prompt "File decompression options"
+       depends on SQUASHFS
+       help
+         Squashfs now supports two options for decompressing file
+         data.  Traditionally Squashfs has decompressed into an
+         intermediate buffer and then memcopied it into the page cache.
+         Squashfs now supports the ability to decompress directly into
+         the page cache.
+
+         If unsure, select "Decompress file data into an intermediate buffer"
+
+config SQUASHFS_FILE_CACHE
+       bool "Decompress file data into an intermediate buffer"
+       help
+         Decompress file data into an intermediate buffer and then
+         memcopy it into the page cache.
+
+config SQUASHFS_FILE_DIRECT
+       bool "Decompress files directly into the page cache"
+       help
+         Directly decompress file data into the page cache.
+         Doing so can significantly improve performance because
+         it eliminates a memcpy and it also removes the lock contention
+         on the single buffer.
+
+endchoice
+
+choice
+       prompt "Decompressor parallelisation options"
+       depends on SQUASHFS
+       help
+         Squashfs now supports three parallelisation options for
+         decompression.  Each one exhibits various trade-offs between
+         decompression performance and CPU and memory usage.
+
+         If in doubt, select "Single threaded compression"
+
+config SQUASHFS_DECOMP_SINGLE
+       bool "Single threaded compression"
+       help
+         Traditionally Squashfs has used single-threaded decompression.
+         Only one block (data or metadata) can be decompressed at any
+         one time.  This limits CPU and memory usage to a minimum.
+
+config SQUASHFS_DECOMP_MULTI
+       bool "Use multiple decompressors for parallel I/O"
+       help
+         By default Squashfs uses a single decompressor but it gives
+         poor performance on parallel I/O workloads when using multiple CPU
+         machines due to waiting on decompressor availability.
+
+         If you have a parallel I/O workload and your system has enough memory,
+         using this option may improve overall I/O performance.
+
+         This decompressor implementation uses up to two parallel
+         decompressors per core.  It dynamically allocates decompressors
+         on a demand basis.
+
+config SQUASHFS_DECOMP_MULTI_PERCPU
+       bool "Use percpu multiple decompressors for parallel I/O"
+       help
+         By default Squashfs uses a single decompressor but it gives
+         poor performance on parallel I/O workloads when using multiple CPU
+         machines due to waiting on decompressor availability.
+
+         This decompressor implementation uses a maximum of one
+         decompressor per core.  It uses percpu variables to ensure
+         decompression is load-balanced across the cores.
+
+endchoice
+
 config SQUASHFS_XATTR
        bool "Squashfs XATTR support"
        depends on SQUASHFS
@@ -78,6 +150,28 @@ 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