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authorSergey Senozhatsky <sergey.senozhatsky.work@gmail.com>2015-11-06 16:29:38 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-06 17:50:42 -0800
commit6fe5186f0c7c18a8beb6d96c21e2390df7a12375 (patch)
tree2a8a65b4a48252c2fa9701653e4ef229cd01089a /mm
parent6f0b22760b7d8317569252cc7c36cbed22ebe401 (diff)
zsmalloc: reduce size_class memory usage
Each `struct size_class' contains `struct zs_size_stat': an array of NR_ZS_STAT_TYPE `unsigned long'. For zsmalloc built with no CONFIG_ZSMALLOC_STAT this results in a waste of `2 * sizeof(unsigned long)' per-class. The patch removes unneeded `struct zs_size_stat' members by redefining NR_ZS_STAT_TYPE (max stat idx in array). Since both NR_ZS_STAT_TYPE and zs_stat_type are compile time constants, GCC can eliminate zs_stat_inc()/zs_stat_dec() calls that use zs_stat_type larger than NR_ZS_STAT_TYPE: CLASS_ALMOST_EMPTY and CLASS_ALMOST_FULL at the moment. ./scripts/bloat-o-meter mm/zsmalloc.o.old mm/zsmalloc.o.new add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-39 (-39) function old new delta fix_fullness_group 97 94 -3 insert_zspage 100 86 -14 remove_zspage 141 119 -22 To summarize: a) each class now uses less memory b) we avoid a number of dec/inc stats (a minor optimization, but still). The gain will increase once we introduce additional stats. A simple IO test. iozone -t 4 -R -r 32K -s 60M -I +Z patched base " Initial write " 4145599.06 4127509.75 " Rewrite " 4146225.94 4223618.50 " Read " 17157606.00 17211329.50 " Re-read " 17380428.00 17267650.50 " Reverse Read " 16742768.00 16162732.75 " Stride read " 16586245.75 16073934.25 " Random read " 16349587.50 15799401.75 " Mixed workload " 10344230.62 9775551.50 " Random write " 4277700.62 4260019.69 " Pwrite " 4302049.12 4313703.88 " Pread " 6164463.16 6126536.72 " Fwrite " 7131195.00 6952586.00 " Fread " 12682602.25 12619207.50 Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/zsmalloc.c17
1 files changed, 13 insertions, 4 deletions
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index a8ff24a29693..2858b20dce76 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -167,9 +167,14 @@ enum zs_stat_type {
OBJ_USED,
CLASS_ALMOST_FULL,
CLASS_ALMOST_EMPTY,
- NR_ZS_STAT_TYPE,
};
+#ifdef CONFIG_ZSMALLOC_STAT
+#define NR_ZS_STAT_TYPE (CLASS_ALMOST_EMPTY + 1)
+#else
+#define NR_ZS_STAT_TYPE (OBJ_USED + 1)
+#endif
+
struct zs_size_stat {
unsigned long objs[NR_ZS_STAT_TYPE];
};
@@ -448,19 +453,23 @@ static int get_size_class_index(int size)
static inline void zs_stat_inc(struct size_class *class,
enum zs_stat_type type, unsigned long cnt)
{
- class->stats.objs[type] += cnt;
+ if (type < NR_ZS_STAT_TYPE)
+ class->stats.objs[type] += cnt;
}
static inline void zs_stat_dec(struct size_class *class,
enum zs_stat_type type, unsigned long cnt)
{
- class->stats.objs[type] -= cnt;
+ if (type < NR_ZS_STAT_TYPE)
+ class->stats.objs[type] -= cnt;
}
static inline unsigned long zs_stat_get(struct size_class *class,
enum zs_stat_type type)
{
- return class->stats.objs[type];
+ if (type < NR_ZS_STAT_TYPE)
+ return class->stats.objs[type];
+ return 0;
}
#ifdef CONFIG_ZSMALLOC_STAT