From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesper Dangaard Brouer Subject: Re: [RFC PATCH 10/12] xdp: Add batching support to redirect map Date: Mon, 10 Jul 2017 19:53:55 +0200 Message-ID: <20170710195355.40fd9caa@redhat.com> References: <20170707172115.9984.53461.stgit@john-Precision-Tower-5810> <20170707173759.9984.5709.stgit@john-Precision-Tower-5810> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, davem@davemloft.net, andy@greyhouse.net, daniel@iogearbox.net, ast@fb.com, brouer@redhat.com To: John Fastabend Return-path: Received: from mx1.redhat.com ([209.132.183.28]:56526 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754658AbdGJRyD (ORCPT ); Mon, 10 Jul 2017 13:54:03 -0400 In-Reply-To: <20170707173759.9984.5709.stgit@john-Precision-Tower-5810> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, 07 Jul 2017 10:37:59 -0700 John Fastabend wrote: > diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c > index 36dc13de..656e334 100644 > --- a/kernel/bpf/devmap.c > +++ b/kernel/bpf/devmap.c [...] > > +void __dev_map_insert_ctx(struct bpf_map *map, u32 key) > +{ > + struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map); > + unsigned long *bitmap = this_cpu_ptr(dtab->flush_needed); > + > + set_bit(key, bitmap); > +} I don't like that this adds an atomic op (set_bit) per packet on a fast-path. It shows up on a perf top #6 with xdp_redirect_map. -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer