From 8052c5a66b29d492e0c68d55278f1d50c2fcc8f5 Mon Sep 17 00:00:00 2001 From: Anatol Belski Date: Fri, 27 Mar 2026 13:07:14 +0100 Subject: [PATCH] performance-metrics: Add QCOW2 async L2 cache miss micro benchmark Add micro_bench_qcow_async_l2_cache_miss which reads one cluster from each of num_ops distinct L2 tables through the QcowAsync io_uring path, forcing L2 cache eviction on nearly every read. Signed-off-by: Anatol Belski --- performance-metrics/src/main.rs | 26 +++++++++++++++++++- performance-metrics/src/micro_bench_block.rs | 22 +++++++++++++++++ 2 files changed, 47 insertions(+), 1 deletion(-) diff --git a/performance-metrics/src/main.rs b/performance-metrics/src/main.rs index ede10c953..2e42cc03c 100644 --- a/performance-metrics/src/main.rs +++ b/performance-metrics/src/main.rs @@ -378,7 +378,7 @@ mod adjuster { } } -const TEST_LIST: [PerformanceTest; 96] = [ +const TEST_LIST: [PerformanceTest; 98] = [ PerformanceTest { name: "boot_time_ms", func_ptr: performance_boot_time, @@ -1661,6 +1661,30 @@ const TEST_LIST: [PerformanceTest; 96] = [ }, unit_adjuster: adjuster::s_to_us, }, + PerformanceTest { + name: "micro_block_qcow_async_l2_cache_miss_128_us", + func_ptr: micro_bench_block::micro_bench_qcow_async_l2_cache_miss, + control: PerformanceTestControl { + test_timeout: 10, + test_iterations: 20, + warmup_iterations: 5, + num_ops: Some(128), + ..PerformanceTestControl::default() + }, + unit_adjuster: adjuster::s_to_us, + }, + PerformanceTest { + name: "micro_block_qcow_async_l2_cache_miss_256_us", + func_ptr: micro_bench_block::micro_bench_qcow_async_l2_cache_miss, + control: PerformanceTestControl { + test_timeout: 10, + test_iterations: 20, + warmup_iterations: 5, + num_ops: Some(256), + ..PerformanceTestControl::default() + }, + unit_adjuster: adjuster::s_to_us, + }, ]; fn run_test_with_timeout( diff --git a/performance-metrics/src/micro_bench_block.rs b/performance-metrics/src/micro_bench_block.rs index 9e0c44c21..f545facda 100644 --- a/performance-metrics/src/micro_bench_block.rs +++ b/performance-metrics/src/micro_bench_block.rs @@ -527,3 +527,25 @@ pub fn micro_bench_qcow_async_write(control: &PerformanceTestControl) -> f64 { drain_async_completions(async_io.as_mut(), num_ops); start.elapsed().as_secs_f64() } + +/// Read one cluster from each of num_ops distinct L2 tables in a sparse +/// QCOW2 image through the QcowAsync io_uring path. +/// +/// Returns the total read wall clock time in seconds. +pub fn micro_bench_qcow_async_l2_cache_miss(control: &PerformanceTestControl) -> f64 { + let num_ops = control.num_ops.expect("num_ops required") as usize; + let (_tmp, disk) = util::sparse_qcow_async_tempfile(num_ops); + let mut async_io = disk + .new_async_io(num_ops as u32) + .expect("new_async_io failed"); + + let mut buf = vec![0u8; QCOW_CLUSTER_SIZE as usize]; + let iovec = read_iovec(&mut buf); + + let stride = L2_ENTRIES_PER_TABLE as u64 * QCOW_CLUSTER_SIZE; + let start = Instant::now(); + submit_reads(async_io.as_mut(), num_ops, stride, &[iovec]); + + drain_async_completions(async_io.as_mut(), num_ops); + start.elapsed().as_secs_f64() +}