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[Bug runtime/5194] IO problem on begin/end probes
- From: "hunt at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: 18 Oct 2007 14:25:25 -0000
- Subject: [Bug runtime/5194] IO problem on begin/end probes
- References: <20071018140048.5194.hunt@redhat.com>
- Reply-to: sourceware-bugzilla at sourceware dot org
------- Additional Comments From hunt at redhat dot com 2007-10-18 14:25 -------
OK, this is not something we normally run into. It's easy to force the
situation by calling a sleeping function in a begin probe. This is not
something we normally do, but we might, so we should handle it correctly or
prevent it.
If the begin/end probe does sleep or get interrupted, it might not get the same
cpu when it resumes, which means the output buffer will change without the
previous buffer getting flushed and data will be lost.
IIRC, one of the reasons we enabled preemption was to handle situations where
large arrays are dumped during end probes. If interrupts are disabled, stapio
cannot process the output while it is arriving and the module runs out of
relayfs buffers.
--
What |Removed |Added
----------------------------------------------------------------------------
Severity|critical |normal
Priority|P1 |P2
http://sourceware.org/bugzilla/show_bug.cgi?id=5194
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