From 28aefb20f32d476955908d65d7940ead7f2437a5 Mon Sep 17 00:00:00 2001 From: Alexander Motin Date: Tue, 17 Aug 2021 11:55:34 -0400 Subject: [PATCH] Optimize arc_l2c_only lists assertions It is very expensive and not informative to call multilist_is_empty() for each arc_change_state() on debug builds to check for impossible. Instead implement special index function for arc_l2c_only->arcs_list, multilists, panicking on any attempt to use it. Reviewed-by: Mark Maybee Reviewed-by: Brian Behlendorf Signed-off-by: Alexander Motin Closes #12421 --- module/zfs/arc.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/module/zfs/arc.c b/module/zfs/arc.c index a440d189de62..b821ebba3dda 100644 --- a/module/zfs/arc.c +++ b/module/zfs/arc.c @@ -2579,13 +2579,6 @@ arc_change_state(arc_state_t *new_state, arc_buf_hdr_t *hdr, l2arc_hdr_arcstats_increment_state(hdr); } } - - /* - * L2 headers should never be on the L2 state list since they don't - * have L1 headers allocated. - */ - ASSERT(multilist_is_empty(&arc_l2c_only->arcs_list[ARC_BUFC_DATA]) && - multilist_is_empty(&arc_l2c_only->arcs_list[ARC_BUFC_METADATA])); } void @@ -7462,6 +7455,12 @@ arc_state_multilist_index_func(multilist_t *ml, void *obj) multilist_get_num_sublists(ml)); } +static unsigned int +arc_state_l2c_multilist_index_func(multilist_t *ml, void *obj) +{ + panic("Header %p insert into arc_l2c_only %p", obj, ml); +} + #define WARN_IF_TUNING_IGNORED(tuning, value, do_warn) do { \ if ((do_warn) && (tuning) && ((tuning) != (value))) { \ cmn_err(CE_WARN, \ @@ -7609,14 +7608,18 @@ arc_state_init(void) sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node), arc_state_multilist_index_func); + /* + * L2 headers should never be on the L2 state list since they don't + * have L1 headers allocated. Special index function asserts that. + */ multilist_create(&arc_l2c_only->arcs_list[ARC_BUFC_METADATA], sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node), - arc_state_multilist_index_func); + arc_state_l2c_multilist_index_func); multilist_create(&arc_l2c_only->arcs_list[ARC_BUFC_DATA], sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node), - arc_state_multilist_index_func); + arc_state_l2c_multilist_index_func); zfs_refcount_create(&arc_anon->arcs_esize[ARC_BUFC_METADATA]); zfs_refcount_create(&arc_anon->arcs_esize[ARC_BUFC_DATA]);