initial logical size calculation can also reasonable use the sidecar because it's concurrency-limited

pageserver/src/pgdatadir_mapping.rs

@@ -927,9 +927,9 @@ impl Timeline {
         &self,
         lsn: Lsn,
         ctx: &RequestContext,
+        io_concurrency: IoConcurrency,
     ) -> Result<(), PageReconstructError> {
-        self.list_aux_files_v2(lsn, ctx, IoConcurrency::sequential())
-            .await?;
+        self.list_aux_files_v2(lsn, ctx, io_concurrency).await?;
         Ok(())
     }
 

pageserver/src/tenant/timeline.rs

@@ -2885,6 +2885,14 @@ impl Timeline {
                     crate::metrics::initial_logical_size::START_CALCULATION.retry(circumstances)
                 };
 
+                let io_concurrency = IoConcurrency::spawn_from_conf(
+                    self_ref.conf,
+                    self_ref
+                        .gate
+                        .enter()
+                        .map_err(|_| CalculateLogicalSizeError::Cancelled)?,
+                );
+
                 let calculated_size = self_ref
                     .logical_size_calculation_task(
                         initial_part_end,
@@ -2894,7 +2902,11 @@ impl Timeline {
                     .await?;
 
                 self_ref
-                    .trigger_aux_file_size_computation(initial_part_end, background_ctx)
+                    .trigger_aux_file_size_computation(
+                        initial_part_end,
+                        background_ctx,
+                        io_concurrency,
+                    )
                     .await?;
 
                 // TODO: add aux file size to logical size