Commits on Sep 27, 2017

1. inverval_set: optimize subset_of with sequential search …

   Optimize subset_of to use sequential search when it
   performs better than the lower_bound method, for set
   size ratios smaller than 10. This is analogous to
   intersection_of behavior since commit 825470f.
   
   The subset_of method can be used in some cases as a
   less-expensive alternative to the intersection_of
   method, since subset_of can return early if any element
   of the smaller set is not contained in the larger set,
   and intersection_of has the added burden of storing
   the intersecting elements.
   
   Signed-off-by: Zac Medico <zmedico@gmail.com>

   

   zmedico committed Sep 27, 2017
   Configuration menu

   • View commit details
   • Copy full SHA for 5c37758
   • Browse repository at this point

   Copy the full SHA

   5c37758 View commit details

   Browse the repository at this point in the history

2. osd/PGPool::update: optimize with subset_of …

   Replace expensive inverval_set intersection_of and operator==
   calls with a single subset_of call. I borrowed this idea from
   Piotr Dałek's "osd/PGPool: don't use intermediate interval set"
   patch. The following benchmark program demonstrates a 38%
   performance increase:
   
   #include <iostream>
   #include <chrono>
   #include "include/interval_set.h"
   
   #define NANOSECONDS(d) \
       std::chrono::duration_cast<std::chrono::nanoseconds>(d).count()
   
   typedef uint64_t snapid_t;
   typedef std::chrono::steady_clock::duration duration;
   
   duration PGPool_update_old(const interval_set<snapid_t> &rs) {
     std::chrono::steady_clock::time_point start, end;
     interval_set<snapid_t> newly_removed_snaps, cached_removed_snaps;
   
     // initialize state
     cached_removed_snaps = rs;
   
     // start timed simulation
     start = std::chrono::steady_clock::now();
   
     {
       newly_removed_snaps = cached_removed_snaps;
       interval_set<snapid_t> intersection;
       intersection.intersection_of(newly_removed_snaps, cached_removed_snaps);
   
       assert(intersection == cached_removed_snaps);
       cached_removed_snaps.swap(newly_removed_snaps);
       newly_removed_snaps = cached_removed_snaps;
       newly_removed_snaps.subtract(intersection);
     }
   
     // end timed simulation
     end = std::chrono::steady_clock::now();
   
     return end - start;
   }
   
   duration PGPool_update_new(const interval_set<snapid_t> &rs) {
     std::chrono::steady_clock::time_point start, end;
     interval_set<snapid_t> newly_removed_snaps, cached_removed_snaps;
   
     // initialize state
     cached_removed_snaps = rs;
   
     // start timed simulation
     start = std::chrono::steady_clock::now();
   
     {
       newly_removed_snaps = cached_removed_snaps;
   
       assert(cached_removed_snaps.subset_of(newly_removed_snaps));
       interval_set<snapid_t> removed_snaps = newly_removed_snaps;
       newly_removed_snaps.subtract(cached_removed_snaps);
       cached_removed_snaps.swap(removed_snaps);
     }
   
     // end timed simulation
     end = std::chrono::steady_clock::now();
   
     return end - start;
   }
   
   int main(int argc, char *argv[])
   {
     assert(argc == 3);
     const int sample_count = std::stoi(argv[1]);
     const int interval_count = std::stoi(argv[2]);
     const int interval_distance = 4;
     const int interval_size = 2;
     const int max_offset = interval_count * interval_distance;
     interval_set<snapid_t> removed_snaps;
   
     for (int i = 0; i < max_offset; i += interval_distance)
       removed_snaps.insert(i, interval_size);
   
     duration old_delta(0), new_delta(0);
   
     for (int i = 0; i < sample_count; ++i) {
       old_delta += PGPool_update_old(removed_snaps);
       new_delta += PGPool_update_new(removed_snaps);
     }
   
     float ratio = float(NANOSECONDS(old_delta)) / NANOSECONDS(new_delta);
   
     std::cout << ratio << std::endl;
   }
   
   Suggested-by: Piotr Dałek <piotr.dalek@corp.ovh.com>
   Signed-off-by: Zac Medico <zmedico@gmail.com>

   

   zmedico committed Sep 27, 2017
   Configuration menu

   • View commit details
   • Copy full SHA for 18cbba4
   • Browse repository at this point

   Copy the full SHA

   18cbba4 View commit details

   Browse the repository at this point in the history