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[Bug translator/10507] overhuge BSS for many-uprobe module
- From: "fche at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: 11 Aug 2009 20:34:55 -0000
- Subject: [Bug translator/10507] overhuge BSS for many-uprobe module
- References: <20090810164710.10507.fche@redhat.com>
- Reply-to: sourceware-bugzilla at sourceware dot org
------- Additional Comments From fche at redhat dot com 2009-08-11 20:34 -------
This is an effect of this generated code:
#ifndef MULTIPLE_UPROBES
#define MULTIPLE_UPROBES 256
#endif
#ifndef MAXUPROBES
#define MAXUPROBES (MULTIPLE_UPROBES * 24743)
#endif
static struct stap_uprobe {
union { struct uprobe up; struct uretprobe urp; };
int spec_index;
} stap_uprobes [MAXUPROBES];
IOW, we preallocate 256 * #number-of-probes copies of struct {up|urp}, to
account for up to 256 concurrent processes.
Short of dynamically allocating the uprobe/uretprobe structs as threads
come & go (and correspondingly complicating the uprobe* -> stap_uprobe_specs[]
mapping), we could heuristically turn down that multiplier.
For example, we could guess that a script with thousands of probes is likely
to apply to a smaller number of concurrent processes.
--
http://sourceware.org/bugzilla/show_bug.cgi?id=10507
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