From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <systemtap-return-2655-listarch-systemtap=sources.redhat.com@sourceware.org>
Received: (qmail 26436 invoked by alias); 27 Feb 2006 19:16:16 -0000
Received: (qmail 26428 invoked by uid 22791); 27 Feb 2006 19:16:16 -0000
X-Spam-Status: No, hits=-2.4 required=5.0 	tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS,SUBJ_HAS_UNIQ_ID
X-Spam-Check-By: sourceware.org
Received: from mx1.redhat.com (HELO mx1.redhat.com) (66.187.233.31)     by sourceware.org (qpsmtpd/0.31) with ESMTP; Mon, 27 Feb 2006 19:16:15 +0000
Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) 	by mx1.redhat.com (8.12.11/8.12.11) with ESMTP id k1RJGCSe031885 	for <systemtap@sources.redhat.com>; Mon, 27 Feb 2006 14:16:12 -0500
Received: from pobox.corp.redhat.com (pobox.corp.redhat.com [172.16.52.156]) 	by int-mx1.corp.redhat.com (8.11.6/8.11.6) with ESMTP id k1RJGC118940; 	Mon, 27 Feb 2006 14:16:12 -0500
Received: from vpn83-158.boston.redhat.com (vpn83-158.boston.redhat.com [172.16.83.158]) 	by pobox.corp.redhat.com (8.12.8/8.12.8) with ESMTP id k1RJGANr012405; 	Mon, 27 Feb 2006 14:16:11 -0500
Subject: Re: disabled interrupts (Was bug #2293
From: Martin Hunt <hunt@redhat.com>
To: "Frank Ch. Eigler" <fche@redhat.com>
Cc: systemtap@sources.redhat.com
In-Reply-To: <y0mmzgcd40r.fsf_-_@ton.toronto.redhat.com>
References: <20060207171449.2293.fche@redhat.com> 	 <20060227173251.10706.qmail@sourceware.org> 	 <y0mmzgcd40r.fsf_-_@ton.toronto.redhat.com>
Content-Type: text/plain
Organization: Red Hat Inc.
Date: Mon, 27 Feb 2006 19:16:00 -0000
Message-Id: <1141067769.4794.5.camel@dragon>
Mime-Version: 1.0
X-Mailer: Evolution 2.2.3 (2.2.3-3.fc4)
Content-Transfer-Encoding: 7bit
X-IsSubscribed: yes
Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm
Precedence: bulk
List-Subscribe: <mailto:systemtap-subscribe@sourceware.org>
List-Post: <mailto:systemtap@sourceware.org>
List-Help: <mailto:systemtap-help@sourceware.org>, <http://sourceware.org/lists.html#faqs>
Sender: systemtap-owner@sourceware.org
X-SW-Source: 2006-q1/txt/msg00649.txt.bz2

On Mon, 2006-02-27 at 13:56 -0500, Frank Ch. Eigler wrote:
> hunt wrote:
> 
> > [...] You have now disabled interrupts, so the data [produced by end
> > probes] fills the buffers but stpd cannot empty them.
> 
> How could stpd have emptied them before, in a reliable way?  During an
> "end" probe, or when?  stpd can't run until the next timeslice; we
> never cooperatively schedule out of a probe.

The runtime calls probe_end(), and it used to know it was safe to sleep
while in probe_end(). So if it attempted to send data and no buffers
were available, it would sleep a bit (allowing stpd to precess the data)
and retry (up to a limit), thus ensuring 100% of the data got sent.

Other solutions require fixed limits on the amount of data that can be
sent during probe end.