On Wed, Jun 21, 2023 at 10:42 AM Andres Freund wrote:
> So I am wondering if you're encountering a different kind of problem. As I
> mentioned, I have observed that the pages need to be clean for this to
> work. For me adding a "sync path/to/postgres" makes it work on 6.3.8.
Without
> the sync
Hi,
On 2023-06-21 09:35:36 +0700, John Naylor wrote:
> On Wed, Jun 21, 2023 at 12:46 AM Andres Freund wrote:
> >
> > Hi,
> >
> > On 2023-06-20 10:29:41 -0700, Andres Freund wrote:
> > > On 2023-06-20 10:23:14 +0700, John Naylor wrote:
> > > > Here's a start at that, trying with postmaster only.
On Wed, Jun 21, 2023 at 12:46 AM Andres Freund wrote:
>
> Hi,
>
> On 2023-06-20 10:29:41 -0700, Andres Freund wrote:
> > On 2023-06-20 10:23:14 +0700, John Naylor wrote:
> > > Here's a start at that, trying with postmaster only. Unfortunately, I
get
> > > "MADV_COLLAPSE failed: Invalid argument".
Hi,
On 2023-06-20 10:29:41 -0700, Andres Freund wrote:
> On 2023-06-20 10:23:14 +0700, John Naylor wrote:
> > Here's a start at that, trying with postmaster only. Unfortunately, I get
> > "MADV_COLLAPSE failed: Invalid argument".
>
> I also see that. But depending on the steps, I also see
>
Hi,
On 2023-06-20 10:23:14 +0700, John Naylor wrote:
> Here's a start at that, trying with postmaster only. Unfortunately, I get
> "MADV_COLLAPSE failed: Invalid argument".
I also see that. But depending on the steps, I also see
MADV_COLLAPSE failed: Resource temporarily unavailable
I suspect
On Wed, Jun 14, 2023 at 12:40 PM John Naylor
wrote:
>
> On Sat, Nov 5, 2022 at 3:27 PM Andres Freund wrote:
> > A real version would have to open /proc/self/maps and do this for at
least
> > postgres' r-xp mapping. We could do it for libraries too, if they're
suitably
> > aligned (both in
Hi,
On 2023-06-14 12:40:18 +0700, John Naylor wrote:
> On Sat, Nov 5, 2022 at 3:27 PM Andres Freund wrote:
>
> >/*
> > * Make huge pages out of it. Requires at least linux 6.1. We
> could
> > * fall back to MADV_HUGEPAGE if it fails, but it doesn't do all
> that
> >
On Sat, Nov 5, 2022 at 3:27 PM Andres Freund wrote:
>/*
> * Make huge pages out of it. Requires at least linux 6.1. We
could
> * fall back to MADV_HUGEPAGE if it fails, but it doesn't do all
that
> * much in older kernels.
> */
> #define MADV_COLLAPSE
Hi,
On 2022-11-06 13:56:10 +0700, John Naylor wrote:
> On Sat, Nov 5, 2022 at 3:27 PM Andres Freund wrote:
> > I don't think the dummy functions are a good approach, there were plenty
> > things after it when I played with them.
>
> To be technical, the point wasn't to have no code after it, but
On Sat, Nov 5, 2022 at 3:27 PM Andres Freund wrote:
> > simplified it. Interestingly enough, looking through the commit history,
> > they used to align the segments via linker flags, but took it out here:
> >
> > https://github.com/intel/iodlr/pull/25#discussion_r397787559
> >
> > ...saying "I'm
Hi,
On 2022-11-05 12:54:18 +0700, John Naylor wrote:
> On Sat, Nov 5, 2022 at 1:33 AM Andres Freund wrote:
> > I hacked in a MADV_COLLAPSE (with setarch -R, so that I could just
> hardcode
> > the address / length), and it seems to work nicely.
> >
> > With the weird caveat that on fs one needs
On Sat, Nov 5, 2022 at 1:33 AM Andres Freund wrote:
> > I wonder how far we can get with just using the linker hints to align
> > sections. I know that the linux folks are working on promoting
sufficiently
> > aligned executable pages to huge pages too, and might have succeeded
already.
> >
> >
Hi,
On 2022-11-03 10:21:23 -0700, Andres Freund wrote:
> > - Add a "cold" __asm__ filler function that just takes up space, enough to
> > push the end of the .text segment over the next aligned boundary, or to
> > ~8MB in size.
>
> I don't understand why this is needed - as long as the pages are
Hi,
This nerd-sniped me badly :)
On 2022-11-03 10:21:23 -0700, Andres Freund wrote:
> On 2022-11-02 13:32:37 +0700, John Naylor wrote:
> > I found an MIT-licensed library "iodlr" from Intel [3] that allows one to
> > remap the .text segment to huge pages at program start. Attached is a
> >
Hi,
On 2022-11-02 13:32:37 +0700, John Naylor wrote:
> It's been known for a while that Postgres spends a lot of time translating
> instruction addresses, and using huge pages in the text segment yields a
> substantial performance boost in OLTP workloads [1][2].
Indeed. Some of that we
It's been known for a while that Postgres spends a lot of time translating
instruction addresses, and using huge pages in the text segment yields a
substantial performance boost in OLTP workloads [1][2]. The difficulty is,
this normally requires a lot of painstaking work (unless your OS does
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