On 2/13/20 8:39 AM, Ondrej Mosnacek wrote:
According to profiling of semodule -BN, ebitmap_cardinality() is called
quite often and contributes a lot to the total runtime. Cache its result
in the ebitmap struct to reduce this overhead. The cached value is
invalidated on most modifying operations, but ebitmap_cardinality() is
usually called once the ebitmap doesn't change any more.
After this patch, the time to do 'semodule -BN' on Fedora Rawhide has
decreased from ~14.6s to ~12.4s (2.2s saved).
Signed-off-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
This seems fine but I was wondering how many of the callers of
ebitmap_cardinality() actually need anything more than ebitmap_length()?
---
v2: corrected time values in commit message
libsepol/include/sepol/policydb/ebitmap.h | 1 +
libsepol/src/ebitmap.c | 10 ++++++++++
2 files changed, 11 insertions(+)
diff --git a/libsepol/include/sepol/policydb/ebitmap.h b/libsepol/include/sepol/policydb/ebitmap.h
index e62df01c..53fafdaa 100644
--- a/libsepol/include/sepol/policydb/ebitmap.h
+++ b/libsepol/include/sepol/policydb/ebitmap.h
@@ -37,6 +37,7 @@ typedef struct ebitmap_node {
typedef struct ebitmap {
ebitmap_node_t *node; /* first node in the bitmap */
uint32_t highbit; /* highest position in the total bitmap */
+ unsigned int cardinality; /* cached value of cardinality */
} ebitmap_t;
#define ebitmap_length(e) ((e)->highbit)
diff --git a/libsepol/src/ebitmap.c b/libsepol/src/ebitmap.c
index 6c9951b7..d23444ce 100644
--- a/libsepol/src/ebitmap.c
+++ b/libsepol/src/ebitmap.c
@@ -67,6 +67,7 @@ int ebitmap_union(ebitmap_t * dst, const ebitmap_t * e1)
ebitmap_destroy(dst);
dst->node = tmp.node;
dst->highbit = tmp.highbit;
+ dst->cardinality = 0;
return 0;
}
@@ -128,9 +129,14 @@ int ebitmap_andnot(ebitmap_t *dst, ebitmap_t *e1, ebitmap_t *e2, unsigned int ma
unsigned int ebitmap_cardinality(ebitmap_t *e1)
{
unsigned int i, count = 0;
+
+ if (e1->cardinality || e1->highbit == 0)
+ return e1->cardinality;
+
for (i=ebitmap_startbit(e1); i < ebitmap_length(e1); i++)
if (ebitmap_get_bit(e1, i))
count++;
+ e1->cardinality = count;
return count;
}
@@ -194,6 +200,7 @@ int ebitmap_cpy(ebitmap_t * dst, const ebitmap_t * src)
}
dst->highbit = src->highbit;
+ dst->cardinality = src->cardinality;
return 0;
}
@@ -309,6 +316,7 @@ int ebitmap_set_bit(ebitmap_t * e, unsigned int bit, int value)
free(n);
}
}
+ e->cardinality = 0; /* invalidate cached cardinality */
return 0;
}
prev = n;
@@ -339,6 +347,7 @@ int ebitmap_set_bit(ebitmap_t * e, unsigned int bit, int value)
e->node = new;
}
+ e->cardinality = 0; /* invalidate cached cardinality */
return 0;
}
@@ -358,6 +367,7 @@ void ebitmap_destroy(ebitmap_t * e)
e->highbit = 0;
e->node = 0;
+ e->cardinality = 0;
return;
}
