Re: [PATCH] Prefetch index pages for B-Tree index scans

> But it also looks forgotten. Bringing it back to life would mean
> building the latest kernel with that patch included, replicating the
> benchmarks I ran here, sans pg patch, but with patched kernel, and
> reporting the (hopefully equally dramatic) performance improvements in
> the kernel ML. That would take me quite some time (not used to playing
> with kernels, though it wouldn't be my first time either), though it
> might be worth the effort.

Well, informing linux hackers may help.

> > I don't know how others (BSD, windows, ...) handle this case.
>
> I don't even think windows supports posix_fadvise, but if async_io is
> used (as hinted by the link Lumby posted), it would probably also work
> in windows.
>
> BSD probably supports it the same way linux does.

I though of the opposite way: how do other kernels handle the backwards
prefetch.

>
> > Maybe the strategy to use our own prefetch is better, then I would like
> > to use it also in places where we used to hack to make linux understand
> > that we will benefits from prefetching.
>
> It would at least benefit those installations without the
> latest-in-the-future kernel-with-backwards-readahead.

We're speaking of PostgreSQL 9.3, running cutting edge PostgreSQL and old
kernel in end 2013... Maybe it won't be so latest-in-the-future at this time.

Btw the improvements you are doing looks good, I just add some information
regarding what is achieved around us.

>
> To which places are you referring to, btw?

Maintenance tasks.

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Cédric Villemain +33 (0)6 20 30 22 52
http://2ndQuadrant.fr/
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