Clean up the text

_posts/2019-06-31-high-performance-systems.md

@@ -60,7 +60,7 @@ Even though everyone has different needs, there are still common things to look
 
 Code you wrote is almost certainly not the *only* code running on your hardware. There are many ways the operating system interacts with your program, from interrupts to system calls, that are important to watch for. These are written from a Linux perspective, but Windows does typically have equivalent functionality.
 
-**Scheduling**: There are two parts to this: first, limit the CPU cores that non-critical processes are allowed to run on. This can be accomplished by excluding cores from scheduling ([`isolcpus`](https://www.linuxtopia.org/online_books/linux_kernel/kernel_configuration/re46.html) kernel command-line option), or by setting the `init` process CPU affinity ([`systemd` example](https://access.redhat.com/solutions/2884991). Second, allow critical processes to run on the isolated cores by setting the [processor affinity](https://en.wikipedia.org/wiki/Processor_affinity) using [taskset](https://linux.die.net/man/1/taskset). By default, the kernel is free to schedule any process on any core so it's important to reserve CPU cores exclusively for the important programs. Finally, use [`NO_HZ`](https://github.com/torvalds/linux/blob/master/Documentation/timers/NO_HZ.txt) or [`chrt`](https://linux.die.net/man/1/chrt) to disable scheduling interrupts, and turn off hyper-threading.
+**Scheduling**: The kernel is normally free to schedule any process on any core, so it's important to reserve CPU cores exclusively for the important programs. There are a few parts to this: first, limit the CPU cores that non-critical processes are allowed to run on by excluding cores from scheduling ([`isolcpus`](https://www.linuxtopia.org/online_books/linux_kernel/kernel_configuration/re46.html) kernel command-line option), or by setting the `init` process CPU affinity ([`systemd` example](https://access.redhat.com/solutions/2884991)). Second, set critical processes to run on the isolated cores by setting the [processor affinity](https://en.wikipedia.org/wiki/Processor_affinity) using [taskset](https://linux.die.net/man/1/taskset).  Finally, use [`NO_HZ`](https://github.com/torvalds/linux/blob/master/Documentation/timers/NO_HZ.txt) or [`chrt`](https://linux.die.net/man/1/chrt) to disable scheduling interrupts. Turning off hyper-threading is also likely beneficial.
 
 **System calls**: Reading from a UNIX socket? Writing to a file? In addition to not knowing how long the I/O operation takes, these all trigger expensive [system calls (syscalls)](https://en.wikipedia.org/wiki/System_call). To handle these, the CPU must [context switch](https://en.wikipedia.org/wiki/Context_switch) to the kernel, let the kernel operation complete, then context switch back to your program. We'd rather keep these [to a minimum](https://www.destroyallsoftware.com/talks/the-birth-and-death-of-javascript) (see timestamp 18:20). [Strace](https://linux.die.net/man/1/strace) is your friend for understanding when and where syscalls happen.