Thank you Gordan. 

Do you recall if your testing environment had THP's enabled or disabled?


-----Original Message-----
From: Gordan Bobic via discuss <[email protected]> 
Sent: Wednesday, May 8, 2024 11:00 AM
To: Simon Avery <[email protected]>
Cc: [email protected]
Subject: [MariaDB discuss] Re: TCMalloc with Maria and THPs

FWIW, my own testing showed recently that tcmalloc provides a small but 
measurable performance improvement over the standard allocator.
jemalloc was slightly worse.
The difference between the three is sufficiently small that I don't think there 
is a compelling reason to use a non-standard allocator, unless you have a very 
specific workload that measurably and repeatably benefits from one over the 
others.

On Wed, May 8, 2024 at 12:44 PM Simon Avery via discuss 
<[email protected]> wrote:
>
> Hello
>
> I’m looking to test tcmalloc for use on our ~80 Maria 10.11.[6-7] servers, 
> running either Rocky 8/9 or Debian 12.
>
> A few years ago we moved to using jemalloc which helped resolve or reduce 
> many of the memory leaks on these servers from using the distro’s default 
> malloc.  We still have a couple of machines where Maria eventually uses all 
> the memory until oomkiller steps in – although we’ve largely mitigated that 
> by adopting weekly restarts for them.
>
> Thanks to Sergei Golubchik for his most useful post here on the 5th on the 
> subject of memory leaks, which has got us looking at tcmalloc and also raises 
> the question of Transparent Huge Pages. Sergei cites several reliable sources 
> recommending turning them off for MariaDb and similar databases.
>
>
>
> Now – my question;
>
> tcmalloc’s documentation on tuning at 
> https://google.github.io/tcmalloc/tuning.html
>
>
>
> says “TCMalloc heavily relies on Transparent Huge Pages (THP).” And explains 
> it’s built and tested with THPs enabled and seems to strongly recommend 
> leaving them on.
>
> That contradicts the above articles, leaving me confused about which path is 
> best practice.
>
> It seems that THP’s should be on as advised by tcmalloc, but also off when 
> running MariaDb.
>
> The true answer possibly depends on which has the highest priority in terms 
> of database-specific performance and the ability to manage the memory tightly.
>
> What are others’ views, please?  I’m searching in particular for best 
> practice and real world experiences with tcmalloc.  Also – if it’s unlikely 
> to improve upon jemalloc.
>
>
>
> Simon Avery
>
> Linux Sysadmin: ATASS Sports
>
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