[SYCL][L0] Remove signaled events from wait list by default (intel#3155)

Signed-off-by: Arvind Sudarsanam <[email protected]>

Author: asudarsa

sycl/doc/EnvironmentVariables.md

@@ -29,6 +29,7 @@ subject to change. Do not rely on these variables in production code.
 | SYCL_PI_LEVEL_ZERO_MAX_COMMAND_LIST_CACHE | Positive integer | Maximum number of oneAPI Level Zero Command lists that can be allocated with no reuse before throwing an "out of resources" error. Default is 20000, threshold may be increased based on resource availabilty and workload demand. |
 | SYCL_PI_LEVEL_ZERO_DISABLE_USM_ALLOCATOR | Any(\*) | Disable USM allocator in Level Zero plugin (each memory request will go directly to Level Zero runtime) |
 | SYCL_PI_LEVEL_ZERO_BATCH_SIZE | Integer | Sets a preferred number of commands to batch into a command list before executing the command list. A value of 0 causes the batch size to be adjusted dynamically. A value greater than 0 specifies fixed size batching, with the batch size set to the specified value. The default is 0. |
+| SYCL_PI_LEVEL_ZERO_FILTER_EVENT_WAIT_LIST | Integer | When set to 0, disables filtering of signaled events from wait lists when using the Level Zero backend. The default is 1. |
 | SYCL_PARALLEL_FOR_RANGE_ROUNDING_TRACE | Any(\*) | Enables tracing of parallel_for invocations with rounded-up ranges. |
 | SYCL_DISABLE_PARALLEL_FOR_RANGE_ROUNDING | Any(\*) | Disables automatic rounding-up of parallel_for invocation ranges. |
 | SYCL_ENABLE_PCI | Integer | When set to 1, enables obtaining the GPU PCI address when using the Level Zero backend. The default is 0. |

sycl/plugins/level_zero/pi_level_zero.cpp

@@ -756,7 +756,8 @@ pi_result _pi_queue::executeOpenCommandList() {
 }
 
 static const bool FilterEventWaitList = [] {
-  const bool RetVal = std::getenv("SYCL_PI_LEVEL_ZERO_FILTER_EVENT_WAIT_LIST");
+  const char *Ret = std::getenv("SYCL_PI_LEVEL_ZERO_FILTER_EVENT_WAIT_LIST");
+  const bool RetVal = Ret ? std::stoi(Ret) : 1;
   return RetVal;
 }();