

MySQL Doesn’t Always Suck; This Time it’s AMD - ice799
http://timetobleed.com/mysql-doesnt-always-suck-this-time-its-amd/

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briansmith
I would say MySQL's response sucked plenty. No effort was made to document the
issue for end-users in the release notes. No effort was made to document a
workaround that end-users could implement. No attempt was made to provide a
workaround in the code; if a workaround was truly impossible as claimed, then
why not implement a killswitch to prevnt MySQL from running in such a
configuration?

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smcdow
Workaround? Are you suggesting that MySQL somehow hotpatch the kernel (which
is what would be needed to fix the problem)? When was the last time you saw a
userland process hotpatch a kernel? This issue belongs to the kernel hackers,
not userland people. And a killswitch? Great. Then what? Go buy new hardware?

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briansmith
I don't know the code. Maybe they could work around it by using a different
primitive. They could change the multiprocessing technique in these
configurations. They could change the RPM so that it has a dependency on the a
kernel version where this bug is fixed or a dependency on the specific patch
that fixes it.

I'd rather have MySQL refuse to start in a known-bad configuration than crash
during runtime. Maybe I would have to buy new hardware; most likely I'd just
have to patch the kernel.

Remember, MySQL is a database. For many of its applications, it is important
that it doesn't crash.

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silentbicycle
First of all, this was on OpenSolaris; I don't think it uses RPM packages at
all.

Beyond just not crashing, any good database will already have a LOT of code
dedicated to verifying data consistency. The best thing MySQL can do in that
situation is loudly warn about running on known buggy hardware and then
continue checking that its data hasn't been corrupted.

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jmillikin
The MySQL bug report is for x64 Linux. OpenSolaris is used as an example of
where AMD's bug has been detected and worked around.

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silentbicycle
I must have misread, sorry.

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vicaya
Quick reference: cat /proc/cpuinfo

Your processor is buggy if it's an Opteron family 15, models 32-63 inclusive.

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ice799
Good call. I should have included something like this in my post. I'll update
it and give you a shout-out. Thanks for commenting!

