Monthly Archives: February 2015

Preliminary results from POWER8 optimized CRC32 for MySQL

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So, Anton got some useful code working that I could patch into a MySQL server for testing purposes – a POWER8 optimized CRC32 implementation.

I went with a pretty stock MySQL 5.6.22 (one patch) with sysbench preparing a single 2GB table (10,000,000 rows). I then hacked up innochecksum so that it would only do the correct CRC32 (rather than trying each checksum type). Using the standard CRC32 algorithm it took around three seconds to verify all of the checksums. With a POWER8 optimized CRC32: 0.4-0.5 seconds. Useful speed-up!

I then ran sysbench read/write with 16 threads with oltp-table-size=10000 (on the larger table) to see if there would be an improvement in a “real world” workload. I got about 30% better performance on read/write operations!

Using perf to see where CPU was going, CPU time spent doing CRC32 calculations went down from ~2.5% to ~0.25%!

In theory, we should be able to get about 52GiB/sec of CRC32 out of a 4.1Ghz POWER8 core. I don’t think we’ll be hitting this in MySQL any time soon.

Give us another week or two and we’ll likely have a patch that’s ready to merge.

Initial benchmarks look promising though!

Amounts of RAM for devices so that I no longer have to worry about it.

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I think this is my current “okay, I don’t have to worry about RAM” list currently:

  • Phone/Tablet: 2GB
  • Laptop: 8GB (although 8GB is better… 4GB is tolerable IFF SSD)
  • Development server: 16GB (32GB if shared) (emacs+gcc)
  • Box for testing things: 128GB (virtualization, databases)

This is… kind of mind bending.

Building OpenPower firmware for use in POWER8 Simulator

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Previously, I blogged on how to Run skiboot (OPAL) on the POWER8 Simulator. If you want to build the full Open Power firmware environment, including the Petitboot bootloader and kernel, you can now do so!

My pull request for an op-build target for the simulator has been merged, so you can now do the following three steps to compile a kernel+initramfs to use with your built skiboot for development purposes:

git clone --recursive git@github.com:open-power/op-build.git
cd op-build
. op-build-env
op-build mambo_defconfig && op-build

Then you wait for a whole bunch of time while everything compiles! Afterwards, you should be left with a zImage.epapr in output/images/ that you can copy into your skiboot directory.

With zImage.epapr in your skiboot directory, when you run “make check”, the skiboot test suite will actually launch the simulator to verify that your skiboot code boots all the way to the petitboot prompt!

We now have two boot tests as part of “make check” for skiboot!