Skip to content

[SYCL][L0] Add an env var to control buffer migration in context with single root-device #7178

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Oct 25, 2022
Merged

[SYCL][L0] Add an env var to control buffer migration in context with single root-device #7178

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
1 change: 1 addition & 0 deletions sycl/doc/EnvironmentVariables.md
100644 → 100755
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -238,6 +238,7 @@ variables in production code.</span>
| `SYCL_PI_LEVEL_ZERO_USE_IMMEDIATE_COMMANDLISTS` | Integer | When set to a positive value enables use of Level Zero immediate commandlists, which means there is no batching and all commands are immediately submitted for execution. Default is 0. Note: When immediate commandlist usage is enabled it is necessary to also set SYCL_PI_LEVEL_ZERO_DEVICE_SCOPE_EVENTS to either 0 or 1. |
| `SYCL_PI_LEVEL_ZERO_USE_MULTIPLE_COMMANDLIST_BARRIERS` | Integer | When set to a positive value enables use of multiple Level Zero commandlists when submitting barriers. Default is 1. |
| `SYCL_PI_LEVEL_ZERO_USE_COPY_ENGINE_FOR_FILL` | Integer | When set to a positive value enables use of a copy engine for memory fill operations. Default is 0. |
| `SYCL_PI_LEVEL_ZERO_SINGLE_ROOT_DEVICE_BUFFER_MIGRATION` | Integer | When set to "0" tells to use single root-device allocation for all devices in a context where all devices have same root. Otherwise performs regular buffer migration. Default is 1. |

## Debugging variables for CUDA Plugin

Expand Down
21 changes: 20 additions & 1 deletion sycl/plugins/level_zero/pi_level_zero.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -8812,10 +8812,29 @@ pi_result _pi_buffer::getZeHandle(char *&ZeHandle, access_mode_t AccessMode,
LastDeviceWithValidAllocation = Device;
return PI_SUCCESS;
}
// Reads user setting on how to deal with buffers in contexts where
// all devices have the same root-device. Returns "true" if the
// preference is to have allocate on each [sub-]device and migrate
// normally (copy) to other sub-devices as needed. Returns "false"
// if the preference is to have single root-device allocations
// serve the needs of all [sub-]devices, meaning potentially more
// cross-tile traffic.
//
static const bool SingleRootDeviceBufferMigration = [] {
const char *EnvStr =
std::getenv("SYCL_PI_LEVEL_ZERO_SINGLE_ROOT_DEVICE_BUFFER_MIGRATION");
if (EnvStr)
return (std::stoi(EnvStr) != 0);
// The default is to migrate normally, which may not always be the
// best option (depends on buffer access patterns), but is an
// overall win on the set of the available benchmarks.
return true;
}();

// Peform actual device allocation as needed.
if (!Allocation.ZeHandle) {
if (Context->SingleRootDevice && Context->SingleRootDevice != Device) {
if (!SingleRootDeviceBufferMigration && Context->SingleRootDevice &&
Context->SingleRootDevice != Device) {
// If all devices in the context are sub-devices of the same device
// then we reuse root-device allocation by all sub-devices in the
// context.
Expand Down