From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 39510 invoked by alias); 16 Feb 2017 19:38:34 -0000 Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org Received: (qmail 39501 invoked by uid 89); 16 Feb 2017 19:38:33 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=H*M:d69a, planning, transfer X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 16 Feb 2017 19:38:32 +0000 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 34FC84DD58; Thu, 16 Feb 2017 19:38:32 +0000 (UTC) Received: from t540p.usersys.redhat.com ([10.15.1.231]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id v1GJcVha010291 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 16 Feb 2017 14:38:31 -0500 Subject: Re: Is there a roadmap for the STAP development? To: Arkady References: <481a3f01-df14-ff12-833e-eeb707fa5256@redhat.com> Cc: systemtap@sourceware.org From: David Smith Message-ID: Date: Thu, 16 Feb 2017 19:38:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2017-q1/txt/msg00104.txt.bz2 On 02/14/2017 12:00 PM, Arkady wrote: > On Tue, Feb 14, 2017 at 6:13 PM, David Smith wrote: ... stuff deleted ... >>> * Add RPM spec file supporting automatic build of the kernel driver >>> after kernel updates >> >> What do you mean by "the kernel driver"? > > I need to build the module automatically every time the kernel > updates. I am preparing the RPM/DEB which does the trick, but to have > a generic example in /docs/examples would be nice or even a script > which generates such RPM based on the stap command line options. Hmm, interesting. This sounds a bit like the kmod system that rebuilds external kernel modules when the kernel gets updated. >>> * In the _stp_reserve_bytes() return indication that the trace buffer >>> is overwritten >>> * Add support for zero copy data transfer >> >> You'd have to flesh those last two items out a bit for me to understand >> what you are looking to do. > > When I send the events from the stap module to the user space I am doing > event_type* event = _stp_reserve_bytes(sizeof(event_type)); > event->field1 = value1; > ..... > I do not handle case when _stp_reserve_bytes() starts to overwrite the > data in the trace buffer. It would be cool to have some feedback that > buffer is full or is getting full. In some situations it is better to > drop the event and avoid overwriting the buffer. As a side note I'll state that you seem to be depending on internal systemtap interfaces here by using _stp_reserve_bytes(). In general we try to keep "external" interfaces, like tapsets, compatible between systemtap versions. There is no such guarantee for internal interfaces. (That being said, I know of no plans to change _stp_reserve_bytes().) > In another approach I am planning to use the shared memory for sending > events from the kernel to the user space in one specific case - very > frequent system calls. Similarly to transport.c with zero copy API. Interesting. Yep, that code would be interesting to see. -- David Smith dsmith@redhat.com Red Hat http://www.redhat.com 256.217.0141 (direct) 256.837.0057 (fax)