From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753759Ab1HIMyN (ORCPT ); Tue, 9 Aug 2011 08:54:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:19271 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753612Ab1HIMyM (ORCPT ); Tue, 9 Aug 2011 08:54:12 -0400 Subject: Re: [PATCH] net/9p: Convert net/9p protocol dumps to tracepoints From: Steven Rostedt To: "Aneesh Kumar K.V" , Steven Rostedt Cc: Pekka Enberg , v9fs-developer@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Ingo Molnar In-Reply-To: <87r54u92ok.fsf@skywalker.in.ibm.com> References: <1312890773-15305-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <87r54u92ok.fsf@skywalker.in.ibm.com> Content-Type: text/plain; charset="UTF-8" Organization: Red Hat Date: Tue, 09 Aug 2011 08:53:15 -0400 Message-ID: <1312894395.3064.23.camel@fedora> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2011-08-09 at 18:12 +0530, Aneesh Kumar K.V wrote: > +#define P9_PROTO_DUMP_SZ (16 * 3 + 2 + 16 + 1) Wow, you're making your event have 67 byte arrays, two of them. > +TRACE_EVENT(9p_protocol_dump, > + TP_PROTO(struct p9_client *clnt, struct p9_fcall *pdu), > + > + TP_ARGS(clnt, pdu), > + > + TP_STRUCT__entry( > + __field( __u64, clnt ) > + __field( __u8, type ) > + __field( __u16, tag ) > + __array( unsigned char, line1, P9_PROTO_DUMP_SZ ) > + __array( unsigned char, line2, P9_PROTO_DUMP_SZ ) > + ), Wouldn't it be better to put this as two unsigned char arrays of 16 bytes? > + > + TP_fast_assign( > + const u8 *ptr = pdu->sdata; > + __entry->clnt = (__u64)clnt; > + __entry->type = pdu->id; > + __entry->tag = pdu->tag; > + hex_dump_to_buffer(ptr, 16, 16, > + 1, __entry->line1, P9_PROTO_DUMP_SZ, true); > + hex_dump_to_buffer(ptr + 16, 16, 16, > + 1, __entry->line2, P9_PROTO_DUMP_SZ, true); > + ), > + > + TP_printk("clnt %lu %s(tag = %d)\n%.8x: %s\n%.8x: %s\n", > + (long)__entry->clnt, show_9p_op(__entry->type), > + __entry->tag, 0, __entry->line1, 16 , __entry->line2) Yeah, you would need to make the above ugly to print out the array, but it's not that hard. And you will be saving 102 bytes per event in the ring buffer, which is very expensive real-estate. Not to mention the time it takes to copy all that. -- Steve