Skip to Main Content

DevOps, CI/CD and Automation

Announcement

For appeals, questions and feedback, please email oracle-forums_moderators_us@oracle.com

DAX offloading isn't offloading cores?

1336415Mar 23 2016 — edited Mar 25 2016

Hello,

According to http://www.oracle.com/technetwork/server-storage/sun-sparc-enterprise/documentation/sparc-t7-m7-server-architecture-2702… "These engines can process 32 independent data streams, offloading the processor cores to do other work."

Let's try to pbind "yes > /dev/null" to all threads of single core and then launch vector_in_range() on one of the threads? One execution of vector_in_range() takes about 80ms (zone memory still not increased, case ID: 497386-1217697831), so we will run it in cycle. What we got is CPU time sharing:

   PID USERNAME USR SYS TRP TFL DFL LCK SLP LAT VCX ICX SCL SIG PROCESS/LWP 

  5334 dglushe*  99 1.0 0.0 0.0 0.0 0.0 0.0 0.0   0  60 68K   0 yes/1

  5327 dglushe*  99 1.0 0.0 0.0 0.0 0.0 0.0 0.0   0  60 68K   0 yes/1

  5336 dglushe*  99 1.0 0.0 0.0 0.0 0.0 0.0 0.0   0  60 68K   0 yes/1

  5330 dglushe*  99 1.0 0.0 0.0 0.0 0.0 0.0 0.0   0  60 68K   0 yes/1

  5332 dglushe*  99 1.0 0.0 0.0 0.0 0.0 0.0 0.0   0  60 68K   0 yes/1

  5340 dglushe*  99 1.0 0.0 0.0 0.0 0.0 0.0 0.0   0  60 68K   0 yes/1

  5338 dglushe*  99 1.0 0.0 0.0 0.0 0.0 0.0 0.0   0  60 68K   0 yes/1

  5345 dglushe*  46  14 0.1 0.0 0.0 0.0 0.0  39   0  48 .1M   0 dax-in-range/1

  5342 dglushe*  39 0.4 0.0 0.0 0.0 0.0 0.0  61   0  49 24K   0 yes/1

Most of the user time dax-in-range spends in following stack:

libdax.so.1`dax_read_results+0x1c4

libdax_query.so.1`dax_query_execute+0x160

libdax_query.so.1`dax_scan+0xdb4

vector.so`dax_scan+0x12c

vector.so`vectorScanStream+0x1d8

vector.so`vectorFilter+0x418

vector.so`vectorInRange+0x2c

vector.so`vector_in_range+0x24

dax-in-range`main+0x1d0

dax-in-range`_start+0x108

Is it poor vector.so that uses DAX ineffectively or the offloading statement is incorrect? vector_in_range() steals time from "yes > /dev/null".

Thank you.

This post has been answered by 1336415 on Mar 25 2016
Jump to Answer
Comments