Friday October 06, 2006 Today's Page Hits: 151
Friday October 06, 2006 Jim Fiori
Apparently the presentation
is normally a 3+ hour presentation and Jim requested 3 hours, but all
the slots are 60min.
This is a presentation on approach not learning D.
This entry is a horrible hack job on content, too much and I am
learning more than I
can easily condense/digest usefully on the fly.
INTRO
Everyone needs
dtrace...but it is not the first thing to run.
Identify a possible issue use Dtrace to figure out what is going on.
Advice: Practice, Practice, Practice
Identify a possible issue use Dtrace to figure out what is going on.
Advice: Practice, Practice, Practice
Approach
use the manual all
examples are in /usr/demo/dtrace
use quantize(), min()/max()/avg() can hide data
Be careful using the PID provider it can impose load on a highly active process.
Normal system tools still have their place.
use quantize(), min()/max()/avg() can hide data
Be careful using the PID provider it can impose load on a highly active process.
Normal system tools still have their place.
New tools: intrstat (some
others I haven't used)
Privs -- Root level or RBAC...
Zero Probe Effect -- via instruction replacement
Scenarios
High User Time
hotuser.sh dtrace toolkit
C++ Apps
Watch for small
allocations and short allocations
High System Calls
(>100s)
use aggregation
use pfiles to determine target of File descriptor
use pfiles to determine target of File descriptor
System time (>10%
or user:sys near 2:1)
Threaded App.
Oracle
prsatst to
find it, dtrace to examine it
Threaded App.
prstat to find it
plockstat ... to see it, single process
Javaplockstat ... to see it, single process
use jstack
Java 1.6 has static dtrace providers
Java 1.6 has static dtrace providers
Oracle
Look at I/O and File
systems first
ONLY after regular investigation by DBA (statspack etc)
ONLY after regular investigation by DBA (statspack etc)
Sybase
Watch for TCP Nagle
(buffering requests before sending)
Try TCP no delay on client and server
Try TCP no delay on client and server
File system
Watch for periodic pauses check autoup in large memory (>8G) systems
Hints and Tools
- Use a sample rate at not quite 1000, to help keep the Dtrace
probe func from running with kernel actions
- Dtrace is running in kernel context...you can't just dump
the memory location, you need to dump the user memory space
- .mul() and .div() are SPARC V7...the application should be
recompiled
- -c flag...use pid$target ... woot
- look for system call errors, when things are not working as
expected
- see atomic_ops(3c) on mutex_lock/unlock for simple variable
updates
- High ctx...look at FX scheduler (good for some apps)
- High Migrations...look at binding to a specific processor
- libumem for memory leaks
- Chime (GUI...uses Sparklines!!!...I like sparklines) OpenSolaris
Coming
- RFE 6311947 svn_43...fun/mod/ufunc/umod
- Dtrace in a zone
- aggregation printing
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