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| -rw-r--r-- | Documentation/vm/zsmalloc.txt | 60 |
1 files changed, 36 insertions, 24 deletions
diff --git a/Documentation/vm/zsmalloc.txt b/Documentation/vm/zsmalloc.txt index 64ed63c4f69d..6e79893d6132 100644 --- a/Documentation/vm/zsmalloc.txt +++ b/Documentation/vm/zsmalloc.txt @@ -1,5 +1,8 @@ +.. _zsmalloc: + +======== zsmalloc --------- +======== This allocator is designed for use with zram. Thus, the allocator is supposed to work well under low memory conditions. In particular, it @@ -31,40 +34,49 @@ be mapped using zs_map_object() to get a usable pointer and subsequently unmapped using zs_unmap_object(). stat ----- +==== With CONFIG_ZSMALLOC_STAT, we could see zsmalloc internal information via -/sys/kernel/debug/zsmalloc/<user name>. Here is a sample of stat output: +``/sys/kernel/debug/zsmalloc/<user name>``. Here is a sample of stat output:: -# cat /sys/kernel/debug/zsmalloc/zram0/classes + # cat /sys/kernel/debug/zsmalloc/zram0/classes class size almost_full almost_empty obj_allocated obj_used pages_used pages_per_zspage - .. - .. + ... + ... 9 176 0 1 186 129 8 4 10 192 1 0 2880 2872 135 3 11 208 0 1 819 795 42 2 12 224 0 1 219 159 12 4 - .. - .. + ... + ... + +class + index +size + object size zspage stores +almost_empty + the number of ZS_ALMOST_EMPTY zspages(see below) +almost_full + the number of ZS_ALMOST_FULL zspages(see below) +obj_allocated + the number of objects allocated +obj_used + the number of objects allocated to the user +pages_used + the number of pages allocated for the class +pages_per_zspage + the number of 0-order pages to make a zspage -class: index -size: object size zspage stores -almost_empty: the number of ZS_ALMOST_EMPTY zspages(see below) -almost_full: the number of ZS_ALMOST_FULL zspages(see below) -obj_allocated: the number of objects allocated -obj_used: the number of objects allocated to the user -pages_used: the number of pages allocated for the class -pages_per_zspage: the number of 0-order pages to make a zspage +We assign a zspage to ZS_ALMOST_EMPTY fullness group when n <= N / f, where -We assign a zspage to ZS_ALMOST_EMPTY fullness group when: - n <= N / f, where -n = number of allocated objects -N = total number of objects zspage can store -f = fullness_threshold_frac(ie, 4 at the moment) +* n = number of allocated objects +* N = total number of objects zspage can store +* f = fullness_threshold_frac(ie, 4 at the moment) Similarly, we assign zspage to: - ZS_ALMOST_FULL when n > N / f - ZS_EMPTY when n == 0 - ZS_FULL when n == N + +* ZS_ALMOST_FULL when n > N / f +* ZS_EMPTY when n == 0 +* ZS_FULL when n == N |