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Tag Archives: gdb
more on PMP
Lately we have been especially enjoying the opportunities that Poor Man’s Profiler provides us – but also the technology has improved a lot too – there have been few really useful mutations. One mutation (hyper-pmp) was Ryan Mack’s approach of … Continue reading
Read ahead…
Mark wrote about how to find situations where InnoDB read-ahead is a bottleneck. What he didn’t disclose, though, is his trick to disable read-ahead without restart or recompile of MySQL. See, there’s no internal “disable read ahead knob”. But there … Continue reading
When bad things happen!
When bad things happen, like… ‘strace -f’ or ‘gdb’ or any other process inspection tool decides to hang your precious processes (they show up in state T in process lists), there’s always help: #include <sys/ptrace.h> #include <signal.h> main(int ac, char … Continue reading
GDB 7!
I wasn’t prepared for this. After spending months playing with GDB development trees I somehow entirely missed that 7.0 release is getting close, and took me more than an hour to spot it. My favorite features are python scripting and … Continue reading
Evil replication management
When one wants to script automated replication chain building, certain things are quite annoying, like immutable replication configuration variables. For example, at certain moments log_slave_updates is more than needed, and thats what the server says: mysql> show variables like ‘log_slave_updates’; … Continue reading
On binaries and -fomit-frame-pointer
Over last few years 64-bit x86 platform has became ubiquitous, thus making stupid memory limitations a thing of some forgotten past. 64-bit processors made internal memory structures bigger, but compensated that with twice the amount and twice larger registers. But … Continue reading
Checksums again, some I/O too
When I was doing data loading tests, I realized that usually low checksum calculation CPU percentage is actually the blocking factor. See, usually when background writers do the flushing, it gets parallelized, but if active query is forcing a checkpoint, … Continue reading
stupid innodb tricks
When it comes to extreme tuning, this is how I got +5% performance in one of my tests on 8-cpu machine (contended at mtr_commit()): gdb -p $(pidof mysqld) -ex “set srv_spin_wait_delay=50″ -batch P.S. was probably worth posting this just to … Continue reading
Poor man’s contention profiling
I wrote already about poor man’s query profiling techniques last summer. Today I’m going to share poor man’s contention profiling tool, for all these poor souls which do not have Solaris with dtrace or pstack, don’t want to run tcmalloc … Continue reading
