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FS-Cache: Add use of /proc and presentation of statistics

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Make FS-Cache create its /proc interface and present various statistical
information through it.  Also provide the functions for updating this
information.

These features are enabled by:

	CONFIG_FSCACHE_PROC
	CONFIG_FSCACHE_STATS
	CONFIG_FSCACHE_HISTOGRAM

The /proc directory for FS-Cache is also exported so that caching modules can
add their own statistics there too.

The FS-Cache module is loadable at this point, and the statistics files can be
examined by userspace:

	cat /proc/fs/fscache/stats
	cat /proc/fs/fscache/histogram

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
This commit is contained in:
David Howells
2009-04-03 16:42:37 +01:00
parent 06b3db1b9b
commit 7394daa8c6
10 changed files with 566 additions and 17 deletions
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6
Documentation/filesystems/caching/backend-api.txt
View File

@@ -100,12 +100,6 @@ A sysfs directory called /sys/fs/fscache/<cachetag>/ is created if CONFIG_SYSFS
is enabled. This is accessible through the kobject struct fscache_cache::kobj
and is for use by the cache as it sees fit.
The cache driver may create itself a directory named for the cache type in the
/proc/fs/fscache/ directory. This is available if CONFIG_FSCACHE_PROC is
enabled and is accessible through:
struct proc_dir_entry *proc_fscache;
========================
RELEVANT DATA STRUCTURES

12
Documentation/filesystems/caching/fscache.txt
View File

@@ -195,7 +195,6 @@ STATISTICAL INFORMATION
If FS-Cache is compiled with the following options enabled:
CONFIG_FSCACHE_PROC=y (implied by the following two)
CONFIG_FSCACHE_STATS=y
CONFIG_FSCACHE_HISTOGRAM=y
@@ -275,7 +274,7 @@ proc files.
(*) /proc/fs/fscache/histogram
cat /proc/fs/fscache/histogram
+HZ +TIME OBJ INST OP RUNS OBJ RUNS RETRV DLY RETRIEVLS
JIFS SECS OBJ INST OP RUNS OBJ RUNS RETRV DLY RETRIEVLS
===== ===== ========= ========= ========= ========= =========
This shows the breakdown of the number of times each amount of time
@@ -291,16 +290,16 @@ proc files.
RETRIEVLS Time between beginning and end of a retrieval
Each row shows the number of events that took a particular range of times.
Each step is 1 jiffy in size. The +HZ column indicates the particular
jiffy range covered, and the +TIME field the equivalent number of seconds.
Each step is 1 jiffy in size. The JIFS column indicates the particular
jiffy range covered, and the SECS field the equivalent number of seconds.
=========
DEBUGGING
=========
The FS-Cache facility can have runtime debugging enabled by adjusting the value
in:
If CONFIG_FSCACHE_DEBUG is enabled, the FS-Cache facility can have runtime
debugging enabled by adjusting the value in:
/sys/module/fscache/parameters/debug
@@ -327,4 +326,3 @@ the control file. For example:
echo $((1|8|64)) >/sys/module/fscache/parameters/debug
will turn on all function entry debugging.