Mailinglist Archive: opensuse (389 mails)

< Previous Next >
Re: [opensuse] Transparent Huge Pages
On 17/03/2019 13.36, Dave Howorth wrote:
On Sun, 17 Mar 2019 13:23:35 +0100 "Carlos E. R." <> wrote:
On 17/03/2019 10.45, Per Jessen wrote:
David C. Rankin wrote:
On 03/16/2019 07:31 PM, Dave Howorth wrote:
So why are THP enabled by default? I could understand if they were
set to madvise for example, but are they likely to make a huge
difference on my 8 GB desktop?

And I don't understand why redis recommend a setting of never
rather than madvise, if anybody has any thoughts on that?

I still don't understand why madvise doesn't solve all problems.

I don't even know what huge pages are about. Do you have some link for
dummies out there? :-D

Wikipedia has nothing on THP.

Google points to

<https://docs.mongodb.com/manual/tutorial/transparent-huge-pages/>

¬ęTransparent Huge Pages (THP) is a Linux memory management system that
reduces the overhead of Translation Lookaside Buffer (TLB) lookups on
machines with large amounts of memory by using larger memory pages.

However, database workloads often perform poorly with THP, because they
tend to have sparse rather than contiguous memory access patterns. You
should disable THP on Linux machines to ensure best performance with
MongoDB.¬Ľ


I don't think I understand much of that.

Is 8 GiB of RAM considered "large amount of memory"? So I'm wondering
if I should disable it.



Strange, they are disabled on 42.3.

On my Lenovo laptop with Leap42.3 and 8Gb memory, it is enabled.

cer@Telcontar:~> cat /sys/kernel/mm/transparent_hugepage/enabled
[always] madvise never
cer@Telcontar:~>

I suppose that is disabled. This machine has 8 GiB, a desktop with
15.0

No, that is enabled. The square brackets indicate the chosen option.

Ah, of course.

--
Cheers / Saludos,

Carlos E. R.
(from 15.0 x86_64 at Telcontar)

< Previous Next >
Follow Ups