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authorPhillip Lougher <phillip@squashfs.org.uk>2013-11-18 02:31:36 +0000
committerPhillip Lougher <phillip@squashfs.org.uk>2013-11-20 03:58:03 +0000
commitd208383d640727b70cd6689bc17e67e9b5ebf4ff (patch)
tree03a6146c22473beb13e2ebda605d6a332ddb758b /fs/squashfs/Kconfig
parentcd59c2ec5f37a2bc1315c9324aab6c21d43ffa1a (diff)
Squashfs: add multi-threaded decompression using percpu variable
Add a multi-threaded decompression implementation which uses percpu variables. Using percpu variables has advantages and disadvantages over implementations which do not use percpu variables. Advantages: * the nature of percpu variables ensures decompression is load-balanced across the multiple cores. * simplicity. Disadvantages: it limits decompression to one thread per core. Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Diffstat (limited to 'fs/squashfs/Kconfig')
-rw-r--r--fs/squashfs/Kconfig57
1 files changed, 44 insertions, 13 deletions
diff --git a/fs/squashfs/Kconfig b/fs/squashfs/Kconfig
index 1c6d340fc61f..159bd6676dc2 100644
--- a/fs/squashfs/Kconfig
+++ b/fs/squashfs/Kconfig
@@ -25,6 +25,50 @@ config SQUASHFS
If unsure, say N.
+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
@@ -63,19 +107,6 @@ config SQUASHFS_LZO
If unsure, say N.
-config SQUASHFS_MULTI_DECOMPRESSOR
- bool "Use multiple decompressors for handling parallel I/O"
- depends on SQUASHFS
- 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.
-
- If unsure, say N.
-
config SQUASHFS_XZ
bool "Include support for XZ compressed file systems"
depends on SQUASHFS