Re: Use fadvise in wal replay

> 23 июня 2022 г., в 13:50, Jakub Wartak <Jakub.Wartak@tomtom.com> написал(а):
>
> Thoughts?
The patch leaves 1st 128KB chunk unprefetched. Does it worth to add and extra branch for 120KB after 1st block when
readOff==0?
Or maybe do
+        posix_fadvise(readFile, readOff + XLOG_BLCKSZ, RACHUNK, POSIX_FADV_WILLNEED);
instead of
+        posix_fadvise(readFile, readOff + RACHUNK    , RACHUNK, POSIX_FADV_WILLNEED);
?

> Notes:
> - no GUC, as the default/identical value seems to be the best
I think adding this performance boost on most systems definitely worth 1 syscall per 16 pages. And I believe 128KB to
beoptimal for most storages. And having no GUCs sounds great. 

But storage systems might be different, far beyond benchmarks.
All in all, I don't have strong opinion on having 1 or 0 GUCs to configure this.

I've added patch to the CF.

Thanks!

Best regards, Andrey Borodin.