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ext4: Use tracepoints for mb_history trace file

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The /proc/fs/ext4/<dev>/mb_history was maintained manually, and had a
number of problems: it required a largish amount of memory to be
allocated for each ext4 filesystem, and the s_mb_history_lock
introduced a CPU contention problem.  

By ripping out the mb_history code and replacing it with ftrace
tracepoints, and we get more functionality: timestamps, event
filtering, the ability to correlate mballoc history with other ext4
tracepoints, etc.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o
2009-09-30 00:32:42 -04:00
parent 90576c0b9a
commit 296c355cd6
6 changed files with 182 additions and 348 deletions
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33
fs/ext4/mballoc.h
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@@ -52,18 +52,8 @@ extern u8 mb_enable_debug;
#define mb_debug(n, fmt, a...)
#endif
/*
* with EXT4_MB_HISTORY mballoc stores last N allocations in memory
* and you can monitor it in /proc/fs/ext4/<dev>/mb_history
*/
#define EXT4_MB_HISTORY
#define EXT4_MB_HISTORY_ALLOC 1 /* allocation */
#define EXT4_MB_HISTORY_PREALLOC 2 /* preallocated blocks used */
#define EXT4_MB_HISTORY_DISCARD 4 /* preallocation discarded */
#define EXT4_MB_HISTORY_FREE 8 /* free */
#define EXT4_MB_HISTORY_DEFAULT (EXT4_MB_HISTORY_ALLOC | \
EXT4_MB_HISTORY_PREALLOC)
/*
* How long mballoc can look for a best extent (in found extents)
@@ -217,22 +207,6 @@ struct ext4_allocation_context {
#define AC_STATUS_FOUND 2
#define AC_STATUS_BREAK 3
struct ext4_mb_history {
struct ext4_free_extent orig; /* orig allocation */
struct ext4_free_extent goal; /* goal allocation */
struct ext4_free_extent result; /* result allocation */
unsigned pid;
unsigned ino;
__u16 found; /* how many extents have been found */
__u16 groups; /* how many groups have been scanned */
__u16 tail; /* what tail broke some buddy */
__u16 buddy; /* buddy the tail ^^^ broke */
__u16 flags;
__u8 cr:3; /* which phase the result extent was found at */
__u8 op:4;
__u8 merged:1;
};
struct ext4_buddy {
struct page *bd_buddy_page;
void *bd_buddy;
@@ -247,13 +221,6 @@ struct ext4_buddy {
#define EXT4_MB_BITMAP(e4b) ((e4b)->bd_bitmap)
#define EXT4_MB_BUDDY(e4b) ((e4b)->bd_buddy)
#ifndef EXT4_MB_HISTORY
static inline void ext4_mb_store_history(struct ext4_allocation_context *ac)
{
return;
}
#endif
#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,