Archive for the ‘Presentations’ Category
Posted by Riyaj Shamsudeen on October 6, 2014
While presenting at Oaktable World 2014 in San Fransisco, I discussed the in-memory pre-population speed and indicated that it takes about 30 minutes to 1 hour to load ~300GB of tables. Someone asked me “Why?” and that was a fair question. So, I profiled the in-memory pre-population at startup.
I profiled all in-memory worker sessions using Tanel’s snapper script and also profiled the processes in OS using Linux perf tool with 99Hz sample rate. As there is no other activity in the database server, it is okay to sample everything in the server. Snapper output will indicate where the time is spent; if the time is spent executing in CPU, then the perf report output will tell us the function call stack executing at that CPU cycle. Data from these two profiling methods will help us to understand the root cause of slowness.
- @snapper.sql out,gather=stw 600 10 “select sid from v$session where program like ‘%W00%’”
- Perf tool : perf record -F 99 -u oracle -g sleep 3600
Posted in 12c, in-memory, inmemory, Oracle database internals, Performance tuning, Presentations | Tagged: 12c in-memory, in-memory, kdzu, perf record, perf report, pre-population cpu time, pre-population speed, snapper | Leave a Comment »
Posted by Riyaj Shamsudeen on March 20, 2014
After collaborating with many performance engineers in a RAC database, I have come to realize that there are common pattern among the (mis)diagnosis. This blog about discussing those issues. I talked about this in Hotsos 2014 conference also.
Here are the golden rules of RAC performance diagnostics. These rules may not apply general RAC configuration issues though.
- Beware of top event tunnel vision
- Eliminate infrastructure as an issue
- Identify problem-inducing instance
- Review send-side metrics also
- Use histograms, not just averages
Looks like, this may be better read as a document. So, please use the pdf files of the presentation and a paper. Presentation slide #10 shows indepth coverage on gc buffer busy* wait events. I will try to blog about that slide later (hopefully).
Golden rules of RAC diagnostics paper
Golden rules of rac diagnostics ppt
Scripts mentioned in the presentation can be downloaded here.
Posted in 11g, Performance tuning, Presentations, RAC | Tagged: gc buffer busy, oracle performance, RAC performance, RAC performance diagnostics, RAC performance myths, RAC performance scripts | 3 Comments »
Posted by Riyaj Shamsudeen on February 25, 2014
I will be presenting in HOTSOS symposium 2014 discussing correct methods to diagnose RAC performance issues. Very surprisingly, even very senior performance engineers make mistakes in their analysis while reviewing RAC issues. Come to my presentation and learn the golden rules of RAC performance diagnostics.
Posted in 12c, Performance tuning, Presentations, RAC | Leave a Comment »
Posted by Riyaj Shamsudeen on October 22, 2012
Please join us at the DOUG (DALLAS ORACLE USERS GROUP) Oracle Database Forum meeting on Thursday, October 25, 2012 from 5 pm – 7 pm.
Presented by Riyaj Shamsudeen, OraInternals, & Sahil Thapar:
“Out with the old way, Enter dbms_xplan: A Swiss army knife for performance engineers”
(i) Ability to query access path from memory, AWR repository
(ii) Ability to use cardinality feedback method to understand access plan issues. Few tips from a real world experience will be provided too.
(iii) Ability to understand issues with database links etc.
(iv) Options such as ADVANCED, ALLSTATS etc
(v) Why should you choose dbmx_xplan over tkprof+sql_trace combination?
(vi) Disadvantages of dbms_xplan and a quick introduction to dbms_monitor.
Refreshments sponsored by me :)
Update: Uploading the presentation pdf files. Enjoy :)
Posted in Performance tuning, Presentations | Tagged: dbms_xplan, dbms_xplan advanced, dbms_xplan allstats last, display_awr, display_cursor | 5 Comments »
Posted by Riyaj Shamsudeen on June 15, 2012
Quick note about Jonathan Lewis trip to Dallas: Jonathan Lewis will be presenting two day seminar on two topics, “Beating the Oracle Optimizer” (June 28) and “Troubleshooting and tuning” (June 29th).
The event will be held June 28-29, 2012 at SMU-in-Legacy in Plano, TX.
This is a must-attend event for experienced DBAs and Developers. Especially, if you are planning to upgrade your database/application in the near-future or if you are in the middle of an upgrade, you must attend these two seminars. This seminar series provide enormous value resolving complex Production performance issues.
Click Here for details.
Posted in Performance tuning, Presentations | Tagged: cost based optimizer presentations, oracle performance | Leave a Comment »
Posted by Riyaj Shamsudeen on May 22, 2012
Let’s first discuss how RAC traffic works before continuing. Environment for the discussion is: 2 node cluster with 8K database block size, UDP protocol is used for cache fusion. (BTW, UDP and RDS protocols are supported in UNIX platform; whereas Windows uses TCP protocol).
UDP protocol, fragmentation, and assembly
UDP Protocol is an higher level protocol stack, and it is implemented over IP Protocol ( UDP/IP). Cache Fusion uses UDP protocol to send packets over the wire (Exadata uses RDS protocol though).
MTU defines the Maximum Transfer Unit of an IP packet. Let us consider an example of MTU set to 1500 in a network interface. One 8K block transfer can not be performed with just one IP packet as the IP packet size (1500 bytes) is less than 8K. So, one transfer of UDP packet of 8K size is fragmented to 6 IP packets and sent over the wire. In the receiving side, those 6 packets are reassembled to create one UDP buffer of size 8K. After the assembly, that UDP buffer is delivered to an UDP port of a UNIX process. Usually, a foreground process will listen on that port to receive the UDP buffer.
Read the rest of this entry »
Posted in 11g, Oracle database internals, Performance tuning, Presentations, RAC, video | Tagged: cache fusion mtu, fragmentation and reassembly, gc lost packets, ipfrag_high_thres, ipfrag_low_thres, ipfrag_time, Jumbo frames, MTU, MTU=9000, oracle performance, RAC internals, RAC performance, RAC presentations, RAC training, RAC video, RAC videos, RDS, UDP vs tcp, wireshark | 11 Comments »
Posted by Riyaj Shamsudeen on April 19, 2012
If you are attending Collaborate 2012, you might be interested in my content-rich sessions below :
Session Number: 326
Session Title: SCAN, VIP, HAIP, and other RAC acronyms
Session Date/Time/Room: Tue, Apr 24, 2012 (10:45 AM – 11:45 AM) : Surf C
Session Number: 327
Session Title: Internals and Performance Boot Camp: Truss, pstack, pmap, and more
Session Date/Time/Room: Wed, Apr 25, 2012 (03:00 PM – 04:00 PM) : Palm A
Hope to see you there!
Update: I am uploading presentation files. Presentations are much more recent than the document :-)
Thanks for attending!
Posted in Oracle database internals, Performance tuning, Presentations, RAC | Tagged: collaborate 2012 presentations, haip, pfiles, pmap, pstack, RAC, RAC performance, RAC presentations, scan, semtimedop, strace, truss, vip | 1 Comment »
Posted by Riyaj Shamsudeen on February 27, 2012
Just a quick note, I will be conducting next 2-week advanced RAC Training, online class in March 26-30 and April 9-13.
You can find agenda and other details here .
I received few emails about the training outline. You can find the outline below:
Yes, I do accept Purchase Orders and can invoice you :)
Posted in Presentations, RAC | Tagged: RAC, RAC training, training online | 1 Comment »
Posted by Riyaj Shamsudeen on February 10, 2012
I just uploaded my presentation materials for ‘Truss, pstack etc’ for HOTSOS 2012 symposium , a performance intensive conference, happening right here in my home town Dallas, TX.
I can’t believe, it is been ten years from the start of this annual conference! This is the tenth annual symposium and I have been presenting in this symposium for almost all years except few early years. Quality of presentations and quality of audience is very high in this symposium and many of the audience are repeat audience, almost this feels like an annual pilgrimage to “sanctum of performance”. If you are interested in learning the techniques and methods to debug and resolve performance issues in a correct way, you should definitely consider attending this symposium. To top it off, Jonathan Lewis is conducting Training Day this year.
There are many great authors talking in this symposium.
Let me take this opportunity to welcome you to Dallas and encourage you to attend this symposium !
PS: Mark Bobak has been presenting or attending all ten years of this symposium, kudos Mark! And, Yes, that’s the same Mark Bobak who is the list admin for that most famous oracle-l mailing list.
PPS: Even though I live in Texas, no, I do not ride an horse to commute, instead, I drive a Ford Mustang car.(Incidentally, Mustang means “a small breed of horse, often wild or half wild, found in the southwestern US” as defined by dictionary.com, So, after all, I am driving a string of wild horse).
Posted in Performance tuning, Presentations, RAC | Tagged: hotsos symposium 2012, oracle performance, RAC performance | 1 Comment »
Posted by Riyaj Shamsudeen on February 10, 2012
I will be leaving to Denver in few days to talk about the following presentations in RMOUG 2012. Stop by and say hello to me if you intend to attend RMOUG training days.
My sessions in RMOUG 2012 are
- Room 402:Session 2: Parallel Execution in RAC – Wednesday 10:45 AM to 11:45AM
- Room 4f: Session 10: Troubleshooting RAC background processes – Thursday 1:30PM to 2:30PM
- Room 4f: Session 11: A kind and Gentle introduction to RAC – Thursday 2:45 PM to 3:45 PM
Hope to see you there.
Posted in Performance tuning, Presentations, RAC | Tagged: oracle performance, pstack, RAC presentations, rmoug | 2 Comments »