News for hackers. Stuff that matters.
Re:IO Devices and Latency by crazygringo on Friday March 14, 2025 @09:32AM (#43362498)
> Latency and bandwidth can be made 10x worst by process context switching alone.

No they can't. That doesn't even make sense as a claim regarding bandwidth since SQLite doesn't use any, but please re-read what I said about being a 1% or 5% difference in speed. Not 10x.

Re:IO Devices and Latency by bob1029 on Friday March 14, 2025 @12:40PM (#43364357)
Yes they absolutely can.

Same-core context switching costs a few microseconds.

Going across core complexes can cost tens to hundreds of microseconds.

These figures are several orders of magnitude (5-6) slower than L1 access on the same thread.

Re:IO Devices and Latency by crazygringo on Saturday March 15, 2025 @09:59AM (#43372578)
Hundreds of microseconds? L1 access? I don't have the faintest idea of what you're talking about.

Communication between processes is negligible compared to all of the sequential disk/SSD accesses and processing required for executing queries.

The database isn't stored in L1 and communication isn't taking hundreds of microseconds. I don't know where you're getting your information.

The fact that SQLite is in-process is primarily about simplicity and convenience, not performance. Performance can even be worse, e.g. due to the lack of a query cache.