I notice that when, the system runs out of space and we are trying to get a live core dump there is delay of around 30 minutes to return ENOSPC to the upper layers. This is on AMD64. As I go through the code , I see a change to the amd64 not present in other platforms in sys/amd64/amd64/minidump_machdep.c . Its the retry count set to 5 ( Not sure where that number comes from ). Because of this, the live core generation in our platform is delayed and the memory map keeps increasing( lots of other stuff running ) it makes things worse. I want to make this retry count a tunable so that it can be changed at runtime accordingly.
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A commit references this bug:
Date: Mon Oct 17 22:57:41 UTC 2016
New revision: 307540
Add sysctl to make amd64 minidump retry count tunable at runtime.
Submitted by: RaviPrakash Darbha <firstname.lastname@example.org>
Reviewed by: cemi, markj
Approved by: sjg (mentor)
Obtained from: Juniper Networks
Differential Revision: https://reviews.freebsd.org/D8254