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| <title>Priority Queue Text Modify (Up) Timing Test</title> |
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| <h1>Priority Queue Text <tt>modify</tt> Timing Test - I</h1> |
| <h2><a name="description" id="description">Description</a></h2> |
| <p>This test inserts a number of values with keys from an |
| arbitrary text ([ <a href="references.html#wickland96thirty">wickland96thirty</a> ]) into |
| into a container then modifies each one "up" (<i>i.e.,</i> it |
| makes it larger). It uses <tt>modify</tt> for <tt>pb_ds</tt>'s |
| priority queues; for the STL's priority queues, it pops values |
| from a container until it reaches the value that should be |
| modified, then pushes values back in. It measures the average |
| time for <tt>modify</tt> as a function of the number of |
| values.</p> |
| <p>(The test was executed with <a href="../../../../testsuite/performance/ext/pb_ds/priority_queue_text_modify_timing.cc"><tt>priority_queue_text_modify_up_timing_test</tt></a> |
| thirty_years_among_the_dead_preproc.txt 200 200 2100 t)</p> |
| <h2><a name="purpose" id="purpose">Purpose</a></h2> |
| <p>The test checks the effect of different underlying |
| data structures (see <a href="pq_design.html#pq_imp">Design::Priority |
| Queues::Implementations</a>) for graph algorithms settings. |
| Note that making an arbitrary value larger (in the sense of the |
| priority queue's comparison functor) corresponds to |
| decrease-key in standard graph algorithms [<a href="references.html#clrs2001">clrs2001</a>].</p> |
| <h2><a name="results" id="results">Results</a></h2> |
| <p>Figures <a href="#NPG">NPG</a>, <a href="#NPM">NPM</a>, and |
| <a href="#NPL">NPL</a> show the results for the native priority |
| queues and <tt>pb_ds</tt> 's priority queues in <a href="pq_performance_tests.html#gcc"><u>g++</u></a>, <a href="pq_performance_tests.html#msvc"><u>msvc++</u></a>, and |
| <a href="pq_performance_tests.html#local"><u>local</u></a>, |
| respectively; Figures <a href="#NRTG">NRTG</a>, <a href="#NRTM">NRTM</a>, and <a href="#NRTL">NRTL</a> show the results |
| for the pairing heap and thin heaps in <a href="pq_performance_tests.html#gcc"><u>g++</u></a>, <a href="pq_performance_tests.html#msvc"><u>msvc++</u></a>, and |
| <a href="pq_performance_tests.html#local"><u>local</u></a>, |
| respectively,</p> |
| <div id="NPG_res_div"> |
| <div id="NPG_gcc"> |
| <div id="NPG_priority_queue_text_modify_up_timing_test"> |
| <div id="NPG_pq"> |
| <div id="NPG_Native_and__tt_pb_ds_455tt__priority_queue__tt_modify_455tt__timing_test"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NPG" id="NPG"><img src="priority_queue_text_modify_up_timing_test_gcc.png" alt="no image" /></a></h6>NPG: Native and <tt>pb ds</tt> priority queue <tt>modify</tt> timing test - <a href="pq_performance_tests.html#gcc">g++</a><p>In the above figure, the names in the legends have the following meaning:</p> |
| <ol> |
| <li> |
| n_pq_deque- |
| <tt>std::priority_queue</tt> adapting <tt>std::deque</tt></li> |
| <li> |
| n_pq_vector- |
| <tt>std::priority_queue</tt> adapting <tt>std::vector</tt></li> |
| <li> |
| binary_heap- |
| <a href="priority_queue.html"><tt>priority_queue</tt></a> |
| with <tt>Tag</tt> = <a href="binary_heap_tag.html"><tt>binary_heap_tag</tt></a> |
| </li> |
| <li> |
| rc_binomial_heap- |
| <a href="priority_queue.html"><tt>priority_queue</tt></a> |
| with <tt>Tag</tt> = <a href="rc_binomial_heap_tag.html"><tt>rc_binomial_heap_tag</tt></a> |
| </li> |
| <li> |
| pairing_heap- |
| <a href="priority_queue.html"><tt>priority_queue</tt></a> |
| with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a> |
| </li> |
| <li> |
| binomial_heap- |
| <a href="priority_queue.html"><tt>priority_queue</tt></a> |
| with <tt>Tag</tt> = <a href="binomial_heap_tag.html"><tt>binomial_heap_tag</tt></a> |
| </li> |
| <li> |
| thin_heap- |
| <a href="priority_queue.html"><tt>priority_queue</tt></a> |
| with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a> |
| </li> |
| </ol> |
| </div><div style="width: 100%; height: 20px"></div></div> |
| </div> |
| </div> |
| </div> |
| </div> |
| <div id="NPM_res_div"> |
| <div id="NPM_msvc"> |
| <div id="NPM_priority_queue_text_modify_up_timing_test"> |
| <div id="NPM_pq"> |
| <div id="NPM_Native_and__tt_pb_ds_455tt__priority_queue__tt_modify_455tt__timing_test"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NPM" id="NPM"><img src="priority_queue_text_modify_up_timing_test_msvc.png" alt="no image" /></a></h6>NPM: Native and <tt>pb ds</tt> priority queue <tt>modify</tt> timing test - <a href="pq_performance_tests.html#msvc">msvc++</a><p>In the above figure, the names in the legends have the following meaning:</p> |
| <ol> |
| <li> |
| n_pq_deque- |
| <tt>std::priority_queue</tt> adapting <tt>std::deque</tt></li> |
| <li> |
| n_pq_vector- |
| <tt>std::priority_queue</tt> adapting <tt>std::vector</tt></li> |
| <li> |
| binary_heap- |
| <a href="priority_queue.html"><tt>priority_queue</tt></a> |
| with <tt>Tag</tt> = <a href="binary_heap_tag.html"><tt>binary_heap_tag</tt></a> |
| </li> |
| <li> |
| rc_binomial_heap- |
| <a href="priority_queue.html"><tt>priority_queue</tt></a> |
| with <tt>Tag</tt> = <a href="rc_binomial_heap_tag.html"><tt>rc_binomial_heap_tag</tt></a> |
| </li> |
| <li> |
| pairing_heap- |
| <a href="priority_queue.html"><tt>priority_queue</tt></a> |
| with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a> |
| </li> |
| <li> |
| binomial_heap- |
| <a href="priority_queue.html"><tt>priority_queue</tt></a> |
| with <tt>Tag</tt> = <a href="binomial_heap_tag.html"><tt>binomial_heap_tag</tt></a> |
| </li> |
| <li> |
| thin_heap- |
| <a href="priority_queue.html"><tt>priority_queue</tt></a> |
| with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a> |
| </li> |
| </ol> |
| </div><div style="width: 100%; height: 20px"></div></div> |
| </div> |
| </div> |
| </div> |
| </div> |
| <div id="NPL_res_div"> |
| <div id="NPL_local"> |
| <div id="NPL_priority_queue_text_modify_up_timing_test"> |
| <div id="NPL_pq"> |
| <div id="NPL_Native_and__tt_pb_ds_455tt__priority_queue__tt_modify_455tt__timing_test"><div style = "border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NPL" id= "NPL"><img src="priority_queue_text_modify_up_timing_test_local.png" alt="no image" /></a></h6>NPL: Native and <tt>pb ds</tt> priority queue <tt>modify</tt> timing test - <a href = "pq_performance_tests.html#local">local</a></div><div style = "width: 100%; height: 20px"></div></div> |
| </div> |
| </div> |
| </div> |
| </div> |
| <div id="NRTG_res_div"> |
| <div id="NRTG_gcc"> |
| <div id="NRTG_priority_queue_text_modify_up_timing_test_pairing_thin"> |
| <div id="NRTG_pq"> |
| <div id="NRTG_Pairing_and_thin__priority_queue__tt_modify_455tt__timing_test"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NRTG" id="NRTG"><img src="priority_queue_text_modify_up_timing_test_pairing_thin_gcc.png" alt="no image" /></a></h6>NRTG: Pairing and thin priority queue <tt>modify</tt> timing test - <a href="pq_performance_tests.html#gcc">g++</a><p>In the above figure, the names in the legends have the following meaning:</p> |
| <ol> |
| <li> |
| pairing_heap- |
| <a href="priority_queue.html"><tt>priority_queue</tt></a> |
| with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a> |
| </li> |
| <li> |
| thin_heap- |
| <a href="priority_queue.html"><tt>priority_queue</tt></a> |
| with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a> |
| </li> |
| </ol> |
| </div><div style="width: 100%; height: 20px"></div></div> |
| </div> |
| </div> |
| </div> |
| </div> |
| <div id="NRTM_res_div"> |
| <div id="NRTM_msvc"> |
| <div id="NRTM_priority_queue_text_modify_up_timing_test_pairing_thin"> |
| <div id="NRTM_pq"> |
| <div id="NRTM_Pairing_and_thin__priority_queue__tt_modify_455tt__timing_test"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NRTM" id="NRTM"><img src="priority_queue_text_modify_up_timing_test_pairing_thin_msvc.png" alt="no image" /></a></h6>NRTM: Pairing and thin priority queue <tt>modify</tt> timing test - <a href="pq_performance_tests.html#msvc">msvc++</a><p>In the above figure, the names in the legends have the following meaning:</p> |
| <ol> |
| <li> |
| pairing_heap- |
| <a href="priority_queue.html"><tt>priority_queue</tt></a> |
| with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a> |
| </li> |
| <li> |
| thin_heap- |
| <a href="priority_queue.html"><tt>priority_queue</tt></a> |
| with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a> |
| </li> |
| </ol> |
| </div><div style="width: 100%; height: 20px"></div></div> |
| </div> |
| </div> |
| </div> |
| </div> |
| <div id="NRTL_res_div"> |
| <div id="NRTL_local"> |
| <div id="NRTL_priority_queue_text_modify_up_timing_test_pairing_thin"> |
| <div id="NRTL_pq"> |
| <div id="NRTL_Pairing_and_thin__priority_queue__tt_modify_455tt__timing_test"><div style = "border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NRTL" id= "NRTL"><img src="priority_queue_text_modify_up_timing_test_pairing_thin_local.png" alt="no image" /></a></h6>NRTL: Pairing and thin priority queue <tt>modify</tt> timing test - <a href = "pq_performance_tests.html#local">local</a></div><div style = "width: 100%; height: 20px"></div></div> |
| </div> |
| </div> |
| </div> |
| </div> |
| <h2><a name="observations" id="observations">Observations</a></h2> |
| <p>As noted above, increasing an arbitrary value (in the sense |
| of the priority queue's comparison functor) is very common in |
| graph-related algorithms. In this case, a thin heap (<a href="priority_queue.html"><tt>priority_queue</tt></a> with |
| <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>) |
| outperforms a pairing heap (<a href="priority_queue.html"><tt>priority_queue</tt></a> with |
| <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>). |
| Conversely, <a href="priority_queue_text_push_timing_test.html">Priority Queue Text |
| <tt>push</tt> Timing Test</a>, <a href="priority_queue_text_push_pop_timing_test.html">Priority Queue |
| Text <tt>push</tt> and <tt>pop</tt> Timing Test</a>, <a href="priority_queue_random_int_push_timing_test.html">Priority |
| Queue Random Integer <tt>push</tt> Timing Test</a>, and |
| <a href="priority_queue_random_int_push_pop_timing_test.html">Priority |
| Queue Random Integer <tt>push</tt> and <tt>pop</tt> Timing |
| Test</a> show that the situation is reversed for other |
| operations. It is not clear when to prefer one of these two |
| different types.</p> |
| <p>In this test <tt>pb_ds</tt>'s binary heaps effectively |
| perform modify in linear time. As explained in <a href="pq_design.html#pq_traits">Priority Queue Design::Traits</a>, |
| given a valid point-type iterator, a binary heap can perform |
| <tt>modify</tt> logarithmically. The problem is that binary |
| heaps invalidate their find iterators with each modifying |
| operation, and so the only way to obtain a valid point-type |
| iterator is to iterate using a range-type iterator until |
| finding the appropriate value, then use the range-type iterator |
| for the <tt>modify</tt> operation.</p> |
| <p>The explanation for the STL's priority queues' performance |
| is similar to that in <a href="priority_queue_text_join_timing_test.html">Priority Queue Text |
| <tt>join</tt> Timing Test</a>.</p> |
| <p><a href="pq_performance_tests.html#pq_observations">Priority-Queue |
| Performance Tests::Observations</a> discusses this further and |
| summarizes.</p> |
| </div> |
| </body> |
| </html> |