From 4ba67ef3a1fbb7d8dc5f00de9b93a583d05b38cc Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Thu, 11 Apr 2024 12:22:32 -0700 Subject: net: dqs: make struct dql more cache efficient With the previous change, struct dqs->stall_thrs will be in the hot path (at queue side), even if DQS is disabled. The other fields accessed in this function (last_obj_cnt and num_queued) are in the first cache line, let's move this field (stall_thrs) to the very first cache line, since there is a hole there. This does not change the structure size, since it moves an short (2 bytes) to 4-bytes whole in the first cache line. This is the new structure format now: struct dql { unsigned int num_queued; unsigned int last_obj_cnt; ... short unsigned int stall_thrs; /* XXX 2 bytes hole, try to pack */ ... /* --- cacheline 1 boundary (64 bytes) --- */ ... /* Longest stall detected, reported to user */ short unsigned int stall_max; /* XXX 2 bytes hole, try to pack */ }; Also, read the stall_thrs (now in the very first cache line) earlier, together with dql->num_queued (also in the first cache line). Suggested-by: Jakub Kicinski Suggested-by: Eric Dumazet Signed-off-by: Breno Leitao Link: https://lore.kernel.org/r/20240411192241.2498631-5-leitao@debian.org Signed-off-by: Jakub Kicinski --- include/linux/dynamic_queue_limits.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'include/linux/dynamic_queue_limits.h') diff --git a/include/linux/dynamic_queue_limits.h b/include/linux/dynamic_queue_limits.h index 869afb800ea1..281298e77a15 100644 --- a/include/linux/dynamic_queue_limits.h +++ b/include/linux/dynamic_queue_limits.h @@ -50,6 +50,9 @@ struct dql { unsigned int adj_limit; /* limit + num_completed */ unsigned int last_obj_cnt; /* Count at last queuing */ + /* Stall threshold (in jiffies), defined by user */ + unsigned short stall_thrs; + unsigned long history_head; /* top 58 bits of jiffies */ /* stall entries, a bit per entry */ unsigned long history[DQL_HIST_LEN]; @@ -71,8 +74,6 @@ struct dql { unsigned int min_limit; /* Minimum limit */ unsigned int slack_hold_time; /* Time to measure slack */ - /* Stall threshold (in jiffies), defined by user */ - unsigned short stall_thrs; /* Longest stall detected, reported to user */ unsigned short stall_max; unsigned long last_reap; /* Last reap (in jiffies) */ -- cgit