mm/zsmalloc: add statistics support
PATCH v2 2/2 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 36209Total 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 the future, we can collect other zsmalloc statistics as we need and analyse them.
---
Change in V2:
use array in struct zs_size_stat -- Minchan
add name argument in zs_pool_stat_create when CONFIG_ZSMALLOC_STAT not defined -- Minchan
--- mm/Kconfig | 10 +++ mm/zsmalloc.c | 233 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 239 insertions(+), 4 deletions(-)
mm/Kconfig +10 -0
@@ -601,6 +601,16 @@ 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
mm/zsmalloc.c +229 -4
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