RepoMirrors/haproxy
1
0
Fork 0
mirror of http://git.haproxy.org/git/haproxy.git/ synced 2025-03-10 21:38:16 +00:00
Code Issues Packages Projects Releases Wiki Activity

MINOR: freq_ctr: add opportunistic versions of swrate_add()

Browse Source 
Some uses of swrate_add() only consist in getting a rough estimate of
a frequency. There are cases where speed matters more than accuracy
(e.g. pools). For such use cases, let's just stop looping on the CAS,
if the update fails, another thread is already providing input, and
it's not dramatic to lose the race. All these functions are now
suffixed with "_opportunistic".
This commit is contained in:
Willy Tarreau 2022-12-19 17:19:45 +01:00
parent 284cfc67b8
commit e327b4a73e
1 changed files with 35 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
include/haproxy/freq_ctr.h
View File

@ -348,6 +348,41 @@ static inline unsigned int swrate_add_scaled(unsigned int *sum, unsigned int n,
return new_sum;
}
/* opportunistic versions of the functions above: an attempt is made to update
* the value, but in case of contention, it's not retried. This is fine when
* rough estimates are needed and speed is preferred over accuracy.
*/
static inline uint swrate_add_opportunistic(uint *sum, uint n, uint v)
{
uint new_sum, old_sum;
old_sum = *sum;
new_sum = old_sum - (old_sum + n - 1) / n + v;
HA_ATOMIC_CAS(sum, &old_sum, new_sum);
return new_sum;
}
static inline uint swrate_add_dynamic_opportunistic(uint *sum, uint n, uint v)
{
uint new_sum, old_sum;
old_sum = *sum;
new_sum = old_sum - (n ? (old_sum + n - 1) / n : 0) + v;
HA_ATOMIC_CAS(sum, &old_sum, new_sum);
return new_sum;
}
static inline uint swrate_add_scaled_opportunistic(uint *sum, uint n, uint v, uint s)
{
uint new_sum, old_sum;
old_sum = *sum;
new_sum = old_sum + v * s - div64_32((unsigned long long)(old_sum + n) * s, n);
HA_ATOMIC_CAS(sum, &old_sum, new_sum);
return new_sum;
}
/* Returns the average sample value for the sum <sum> over a sliding window of
* <n> samples. Better if <n> is a power of two. It must be the same <n> as the
* one used above in all additions.