also print duration in the callaback execution

Signed-off-by: shirady <57721533+shirady@users.noreply.github.com>

src/sdk/namespace_fs.js

@@ -1078,7 +1078,10 @@ class NamespaceFS {
                 // TODO buffers_pool and the underlying semaphore should support abort signal
                 // to avoid sleeping inside the semaphore until the timeout while the request is already aborted.
                 const { buffer, callback } = await multi_buffer_pool.get_buffers_pool(remain_size).get_buffer();
+                const start_time = performance.now();
                 buffer_pool_cleanup = callback; // must be called ***IMMEDIATELY*** after get_buffer
+                const end_time = performance.now();
+                dbg.log2(`get_buffer: Time taken to execute callback is ${end_time - start_time} ms.`);
                 object_sdk.throw_if_aborted();
 
                 // read from file