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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 <opensource.ganesh@gmail.com>
Suggested-by: Minchan Kim <minchan@kernel.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Seth Jennings <sjennings@variantweb.net>
Cc: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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