From ca027a1c45e30d89c5cc6dcacbdcea74e1ff65fc Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Wed, 17 Jan 2018 19:13:32 -0800 Subject: [PATCH] nfp: bpf: add short busy wait for FW replies Scheduling out and in for every FW message can slow us down unnecessarily. Our experiments show that even under heavy load the FW responds to 99.9% messages within 200 us. Add a short busy wait before entering the wait queue. Signed-off-by: Jakub Kicinski Signed-off-by: Daniel Borkmann --- drivers/net/ethernet/netronome/nfp/bpf/cmsg.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/netronome/nfp/bpf/cmsg.c b/drivers/net/ethernet/netronome/nfp/bpf/cmsg.c index 71e6586..80d3aa0 100644 --- a/drivers/net/ethernet/netronome/nfp/bpf/cmsg.c +++ b/drivers/net/ethernet/netronome/nfp/bpf/cmsg.c @@ -157,7 +157,14 @@ nfp_bpf_cmsg_wait_reply(struct nfp_app_bpf *bpf, enum nfp_bpf_cmsg_type type, int tag) { struct sk_buff *skb; - int err; + int i, err; + + for (i = 0; i < 50; i++) { + udelay(4); + skb = nfp_bpf_reply(bpf, tag); + if (skb) + return skb; + } err = wait_event_interruptible_timeout(bpf->cmsg_wq, skb = nfp_bpf_reply(bpf, tag), -- 2.7.4