From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Gardner Subject: Re: unconditionally enable the trace buffer Date: Thu, 27 Oct 2005 16:08:38 -0600 Message-ID: <43614FE6.105@hp.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Ian Pratt Cc: xen-devel List-Id: xen-devel@lists.xenproject.org Ian Pratt wrote: >I haven't looked at xentrace in a while, but last time I did it could >seriously do with some tidying up. Here's a list of features I'd like to >see it have. I'd be grateful if you could tell me what the current state >is: > >* ability to turn on/off via hypercall > > Not currently implemented, but would not be difficult to add. >* trace events grouped by type, with a bitmap to enable the event types >of interest > > This functionality is in there already. >* ability to set the per CPU tracebuffer size when turning it on > > Partially; You can enable the trace buffer on the xen (boot) command line, and you can specify the trace buffer size there. You cannot change the size dynamically. >* ability for the user-space reader to explicitly block (select on fd) >on an eventchn notification that the buffer is e.g. half full. (reader >should write out all the pages that are full of trace events) > > Not done. >* user space reader should log when it misses blocks of events >(overwrite last trace message in buffer with a special 'missed X events' >message) > > > Not done, but my XenMon patch includes a change to the trace buffer code to help with this. I've added a "sequence number" to each trace record which can be used to detect when blocks of events have been missed. Rob Gardner