Re: Add progressive backoff to XactLockTableWait functions

Hi,

On Tue, Jun 17, 2025 at 9:38 PM Xuneng Zhou <xunengzhou(at)gmail(dot)com> wrote:

> Hi,
>
> Although it’s clear that replacing tight 1 ms polling loops will reduce
> CPU usage, I'm curious about the hard numbers. To that end, I ran a 60 s
> logical-replication slot–creation workload on a standby using three
> different XactLockTableWait() variants—on an 8-core, 16 GB AMD system—and
> collected both profiling traces and hardware-counter metrics.
>
>
> 1. Hardware‐counter results
>
>
> [image: image.png]
>
>
> - CPU cycles drop by 58% moving from 1 ms to exp. backoff, and another
> 25% to the 1 s threshold variant.
> - Cache‐misses and context‐switches see similarly large reductions.
> - IPC remains around 0.45, dipping slightly under longer sleeps.
>
>
Gmail does not seem to support embedded images, so I’ve included it as an
attachment.

Best regards,

Xuneng