Probably the funniest thing I had ever seen on stage was a two-hander called “Frank ‘n Stein”. It’s a telling of the classic Frankenstein story, with the physical comedy of two actors having to rotate continuously between a large number of roles, including a whole crowd chasing the monster. This was all made possible by them never leaving the stage, but instead changing characters in front of the audience, using only rudimentary props to help differentiate the characters.
If this is the only thing you remember about fiber mode scheduling, it should see you through.
Continue reading “Scheduler stories: The joy of fiber mode”
I am planning to burn a fair number of cycles on SQLOS scheduling internals for the foreseeable future, and with some luck, this turns into an interesting series. OS scheduling is already a subject that belongs “on the other side of the looking glass”, and this only gets more interesting when we look at user-mode SOS_Scheduler scheduling built on top of it.
If I don’t specifically mention a version, my frame of reference is SQL Server 2014. Yes, things changed since then, but the 2012-2014 scheduler is a good starting point, and the fundamental mechanisms I’ll initially cover have changed very little since the User Mode Scheduler (UMS) of SQL Server 7.0.
Continue reading “Scheduler Stories: When does your scheduler run?”
Well, I never. There is life in the old spinlock yet!
Being a synchronisation fetishist, I took great interest in last week’s great blog post by Sanjay Mishra and Arvind Shyamsundar about the ReaderWriterSpinlock added in 2016 CU2. Great story, happy ending, room for a sequel, all good news.
We have already seen recent improvement in the reader-writer lock algorithm, so clearly people are finding more corners to squeeze. Now what, pray tell, is a reader-writer spinlock?
Continue reading “A spanking new ReaderWriterSpinlock”