define two new environment variables to better understand how much
memory is being allocated, and when. This has been invaluable in
inproving the --fit algorithm, and is likely to be useful when debugging
other memory-related issues.
`-lv 4` will be required to enable the following:
GGML_SYCL_MEMTRACE=1 will show per-site memory usage, updated whenever
it increases by more than 64MiB.
GGML_SYCL_MEMTRACE=2 will show every allocation and deallocation.
To change the default 64MiB threshold for reporting memory usage increases, use
GGML_SYCL_MEMTRACE_STEP.
A sample log line:
[SYCL-MEMTRACE] device memory query (dev): total 59493 MiB, free 4494, in use 54998; allocated 0 (buffers 0 + scratch 0), peak 0 MiB