Hi,
On 2020-06-19 17:42:41 +1200, Thomas Munro wrote:
> On Thu, Jun 18, 2020 at 6:05 PM Thomas Munro <thomas.munro@gmail.com> wrote:
> > Here's a version that adds some documentation.
>
> I jumped on a dual socket machine with 36 cores/72 threads and 144GB
> of RAM (Azure F72s_v2) running Linux, configured with 50GB of huge
> pages available, and I ran a very simple test: select count(*) from t
> t1 join t t2 using (i), where the table was created with create table
> t as select generate_series(1, 400000000)::int i, and then prewarmed
> into 20GB of shared_buffers.
I assume all the data fits into 20GB?
Which kernel version is this?
How much of the benefit comes from huge pages being used, how much from
avoiding the dsm overhead, and how much from the page table being shared
for that mapping? Do you have a rough idea?
Greetings,
Andres Freund