Re: High number of created consistent read blocks when inserting into a LOB column from dblink

From: Stefan Koehler <contact_at_soocs.de>
Date: Thu, 12 Jan 2017 18:49:36 +0100 (CET)
Message-ID: <545418714.1583319.1484243376626.JavaMail.open-xchange_at_app01.ox.hosteurope.de>


Hey Jure,
sorry, i did not get your point with flame-graph. How did you capture the stack traces - with perf?

If yes, perf only samples on-CPU processes/events by default which means that you captured nothing and the other stuff might be irrelevant when your process wasn't mostly on CPU. However you also can sample off-CPU processes/events with perf: http://www.brendangregg.com/blog/2015-02-26/linux-perf-off-cpu-flame-graph.html

Best Regards
Stefan Koehler

Independent Oracle performance consultant and researcher Homepage: http://www.soocs.de
Twitter: _at_OracleSK

> Jure Bratina <jure.bratina_at_gmail.com> hat am 12. Januar 2017 um 17:55 geschrieben:
>
> Regarding the problematic database, I made a quick flamegraph analysis on it when wasn't mostly on CPU, and a large portion of the time was spent
> in functions which seem to manage LOB space, e.g. kdliAllocChunks, ktsl_fill_dispenser_main, ktsla_ins_chunk, so like it was mentioned, it seems
> that the problem lies in the LOB space management, however the root cause of the slowdown on the problematic database is (still) unknown.
>
> Regards,
> Jure Bratina
 

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Received on Thu Jan 12 2017 - 18:49:36 CET

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