From mboxrd@z Thu Jan 1 00:00:00 1970 From: Namhyung Kim Subject: Re: perf probe and bitfields Date: Fri, 26 Jan 2018 15:56:56 +0900 Message-ID: <20180126065656.GD22737@sejong> References: <52f06b83-1065-dc88-756e-7f8fffc5c21e@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Received: from LGEAMRELO13.lge.com ([156.147.23.53]:47364 "EHLO lgeamrelo13.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751192AbeAZG46 (ORCPT ); Fri, 26 Jan 2018 01:56:58 -0500 Content-Disposition: inline In-Reply-To: <52f06b83-1065-dc88-756e-7f8fffc5c21e@gmail.com> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: David Ahern Cc: Arnaldo Carvalho de Melo , Masami Hiramatsu , Perf Users , kernel-team@lge.com Hi David, On Fri, Jan 19, 2018 at 08:43:50AM -0800, David Ahern wrote: > Hi Arnaldo / Masami: > > Are there known issues / limitations with perf probe and bitfields? > > Here's an example: pkt_type is a bitfield in sk_buff. When I put a probe > in arp_rcv to examine the pkt_type value: > > $ perf probe 'arp_rcv ptype=skb->pkt_type dev=dev->name:string' Bitfield type takes 3 parameters according to the Doc/perf-probe.txt. Maybe it's like 'ptype=skb->pkt_type:b3@0/8' ? Thanks, Namhyung > > I only get '0' output: > > $ perf script > vhost-27472 27483 [013] 4313207.619714: probe:arp_rcv: > (ffffffff815653b0) ptype=0 dev="br1" > vhost-27472 27483 [013] 4313207.619763: probe:arp_rcv: > (ffffffff815653b0) ptype=0 dev="br1" > vhost-27472 27483 [013] 4313210.588990: probe:arp_rcv: > (ffffffff815653b0) ptype=0 dev="br1" > > when I know broadcast packet are getting handled (pkt_type == > PACKET_BROADCAST). This is confirmed by adding a printk to arp_rcv. > > Thanks, > David > -- > To unsubscribe from this list: send the line "unsubscribe linux-perf-users" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html