mm/zsmalloc: add statistics support

Keeping fragmentation of zsmalloc in a low level is our target.  But now
we still need to add the debug code in zsmalloc to get the quantitative
data.

This patch adds a new configuration CONFIG_ZSMALLOC_STAT to enable the
statistics collection for developers.  Currently only the objects
statatitics in each class are collected.  User can get the information via
debugfs.

     cat /sys/kernel/debug/zsmalloc/zram0/...

For example:

After I copied "jdk-8u25-linux-x64.tar.gz" to zram with ext4 filesystem:
 class  size obj_allocated   obj_used pages_used
     0    32             0          0          0
     1    48           256         12          3
     2    64            64         14          1
     3    80            51          7          1
     4    96           128          5          3
     5   112            73          5          2
     6   128            32          4          1
     7   144             0          0          0
     8   160             0          0          0
     9   176             0          0          0
    10   192             0          0          0
    11   208             0          0          0
    12   224             0          0          0
    13   240             0          0          0
    14   256            16          1          1
    15   272            15          9          1
    16   288             0          0          0
    17   304             0          0          0
    18   320             0          0          0
    19   336             0          0          0
    20   352             0          0          0
    21   368             0          0          0
    22   384             0          0          0
    23   400             0          0          0
    24   416             0          0          0
    25   432             0          0          0
    26   448             0          0          0
    27   464             0          0          0
    28   480             0          0          0
    29   496            33          1          4
    30   512             0          0          0
    31   528             0          0          0
    32   544             0          0          0
    33   560             0          0          0
    34   576             0          0          0
    35   592             0          0          0
    36   608             0          0          0
    37   624             0          0          0
    38   640             0          0          0
    40   672             0          0          0
    42   704             0          0          0
    43   720            17          1          3
    44   736             0          0          0
    46   768             0          0          0
    49   816             0          0          0
    51   848             0          0          0
    52   864            14          1          3
    54   896             0          0          0
    57   944            13          1          3
    58   960             0          0          0
    62  1024             4          1          1
    66  1088            15          2          4
    67  1104             0          0          0
    71  1168             0          0          0
    74  1216             0          0          0
    76  1248             0          0          0
    83  1360             3          1          1
    91  1488            11          1          4
    94  1536             0          0          0
   100  1632             5          1          2
   107  1744             0          0          0
   111  1808             9          1          4
   126  2048             4          4          2
   144  2336             7          3          4
   151  2448             0          0          0
   168  2720            15         15         10
   190  3072            28         27         21
   202  3264             0          0          0
   254  4096         36209      36209      36209

 Total               37022      36326      36288

We can calculate the overall fragentation by the last line:
    Total               37022      36326      36288
    (37022 - 36326) / 37022 = 1.87%

Also by analysing objects alocated in every class we know why we got so
low fragmentation: Most of the allocated objects is in <class 254>.  And
there is only 1 page in class 254 zspage.  So, No fragmentation will be
introduced by allocating objs in class 254.

And in future, we can collect other zsmalloc statistics as we need and
analyse them.

Signed-off-by: Ganesh Mahendran <[email protected]>
Suggested-by: Minchan Kim <[email protected]>
Acked-by: Minchan Kim <[email protected]>
Cc: Nitin Gupta <[email protected]>
Cc: Seth Jennings <[email protected]>
Cc: Dan Streetman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Ganesh Mahendran 2015-02-12 15:00:54 -08:00 • committed by Linus Torvalds
commit 0f050d997e
2 changed files with 239 additions and 4 deletions

View file

@ -602,6 +602,16 @@ config PGTABLE_MAPPING
You can check speed with zsmalloc benchmark:
https://github.com/spartacus06/zsmapbench
config ZSMALLOC_STAT
bool "Export zsmalloc statistics"
depends on ZSMALLOC
select DEBUG_FS
help
This option enables code in the zsmalloc to collect various
statistics about whats happening in zsmalloc and exports that
information to userspace via debugfs.
If unsure, say N.
config GENERIC_EARLY_IOREMAP
bool