Functions for selecting current device

[PokhodenkoSA]

Now current device is changed via dpctl.device_context. Internally it changes current device at enter to context and return previous device on exit from context. Functions for changing current device should be provided in API.

Functions:

• select_device
• close

Also functions could provide access to internal contexts stack.

[diptorupd]

@PokhodenkoSA can you clarify what exactly needs to be done here? The concept of default queue is going to go away from dpctl. Instead we can make the dpctl._SyclQueueManager class public and numba-dppy can use it to manage a current queue for numba-dppy.

Also, the recent changes that got merged into master adds an API call dpctl.set_global_queue to change the current queue without having to use a with dpctl.device_context. The function previously existed as dpctl.set_default_queue.

[PokhodenkoSA]

@diptorupd I propose to meet and discuss it.

[diptorupd]

The device manager has been significantly modified to let users create SYCL devices as they wish. The notion of current device is deprecated and we will not have the feature in dpctl eventually. @oleksandr-pavlyk Fine with closing the issue?

[oleksandr-pavlyk]

Vote to close.

[PokhodenkoSA]

@diptorupd
What we have now instead of current device?

[oleksandr-pavlyk]

Explicit creation of devices/queues.

• dpctl.SyclDevice() gives default selected device
• dpctl.SyclQueue() gives queue constructed from default selector.
• dpctl.SyclQueue(filter_string) constructs sycl queue from given filter selector string.

[PokhodenkoSA]

How dpctl.device_context() is working now? Does not it change some variable which is used buy code inside the context?

[oleksandr-pavlyk]

dpctl.device_context currently works by manipulating a singleton class implementing a stack. The global nature of this class makes it async-unsafe, e.g. #11.

With adoption of computation follows data paradigm, dpctl.device_context becomes deprecated and should eventually be removed.

[PokhodenkoSA]

Thanks.

[diptorupd]

Closing as the design based on a "current device" has been removed and the device manager code is also slotted to be removed.