Simon Riggs wrote:
> On Sat, 2007-03-10 at 07:59 +0000, Simon Riggs wrote:
>> On Fri, 2007-03-09 at 18:05 -0500, Tom Lane wrote:
>>> "Simon Riggs" <simon@2ndquadrant.com> writes:
>>>> On Fri, 2007-03-09 at 16:45 -0500, Tom Lane wrote:
>>>>> We do that anyway; but certainly Simon's patch ought not be injecting
>>>>> an additional one.
>>>> It should be possible to pass that down from the planner to the
>>>> executor, in certain cases.
>>> Huh? See HeapScanDesc->rs_nblocks.
>> Many thanks.
>
> New patch enclosed, implementation as you've requested.
>
> Not ready to apply yet, but good for testing.
>

A quick test using the setup for "Buffer cache is not scan resistant"
thread:

Firstly vanilla 8.3 from 20070310:

Shared Buffers Elapsed vmstat IO rate
-------------- ------- --------------
400MB 101 s 122 MB/s
128KB 79 s 155 MB/s [1]

Now apply cycle scan v2:

Shared Buffers Scan_recycle_buffers Elapsed vmstat IO rate
-------------- -------------------- ------- -------------
400MB 0 101 s 122 MB/s
400MB 8 78 s 155 MB/s
400MB 16 77 s 155 MB/s
400MB 32 78 s 155 MB/s
400MB 64 82 s 148 MB/s
400MB 128 93 s 128 MB/s

Certainly seems to have the desired effect!

Cheers

Mark

[1] I'm not seeing 166 MB/s like previous 8.2.3 data, however 8.3 PGDATA
is located further toward the end of the disk array - which I suspect is
limiting the IO rate a little.

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On Sat, 2007-03-10 at 23:26 +1300, Mark Kirkwood wrote:
> Simon Riggs wrote:
> > New patch enclosed, implementation as you've requested.
> >
> > Not ready to apply yet, but good for testing.
> >
>
> A quick test using the setup for "Buffer cache is not scan resistant"
> thread:
>
> Firstly vanilla 8.3 from 20070310:
>
> Shared Buffers Elapsed vmstat IO rate
> -------------- ------- --------------
> 400MB 101 s 122 MB/s
> 128KB 79 s 155 MB/s [1]
>
> Now apply cycle scan v2:
>
> Shared Buffers Scan_recycle_buffers Elapsed vmstat IO rate
> -------------- -------------------- ------- -------------
> 400MB 0 101 s 122 MB/s
> 400MB 8 78 s 155 MB/s
> 400MB 16 77 s 155 MB/s
> 400MB 32 78 s 155 MB/s
> 400MB 64 82 s 148 MB/s
> 400MB 128 93 s 128 MB/s
>
> Certainly seems to have the desired effect!
>
> Cheers
>
> Mark
>
> [1] I'm not seeing 166 MB/s like previous 8.2.3 data, however 8.3 PGDATA
> is located further toward the end of the disk array - which I suspect is
> limiting the IO rate a little.

That's good news, thanks very much for testing that.

Before we can claim success, we need a few more tests on VACUUM, COPY
and a null test case to show it doesn't effect typical workloads, except
to improve vacuuming. I'll see if we can arrange those at EDB on a
reasonable size system.

--
Simon Riggs
EnterpriseDB http://www.enterprisedb.com



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Where is the final version of this patch? What patches are stuck in the
patch moderator queue?

---------------------------------------------------------------------------

Simon Riggs wrote:
> On Sat, 2007-03-10 at 07:59 +0000, Simon Riggs wrote:
> > On Fri, 2007-03-09 at 18:05 -0500, Tom Lane wrote:
> > > "Simon Riggs" <simon@2ndquadrant.com> writes:
> > > > On Fri, 2007-03-09 at 16:45 -0500, Tom Lane wrote:
> > > >> We do that anyway; but certainly Simon's patch ought not be injecting
> > > >> an additional one.
> > >
> > > > It should be possible to pass that down from the planner to the
> > > > executor, in certain cases.
> > >
> > > Huh? See HeapScanDesc->rs_nblocks.
> >
> > Many thanks.
>
> New patch enclosed, implementation as you've requested.
>
> Not ready to apply yet, but good for testing.
>
> COPY command now also uses this hint, to allow test results and
> discussion. Others could also, perhaps needing different values.
>
> --
> Simon Riggs
> EnterpriseDB http://www.enterprisedb.com
>

[ Attachment, skipping... ]

>
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--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://www.enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +

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On Mon, 2007-04-02 at 19:10 -0400, Bruce Momjian wrote:

> Where is the final version of this patch? What patches are stuck in the
> patch moderator queue?

We already discussed the dependency that exists with this patch and you
accepted that.

--
Simon Riggs
EnterpriseDB http://www.enterprisedb.com



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Simon Riggs wrote:
> On Mon, 2007-04-02 at 19:10 -0400, Bruce Momjian wrote:
>
> > Where is the final version of this patch? What patches are stuck in the
> > patch moderator queue?
>
> We already discussed the dependency that exists with this patch and you
> accepted that.

Oh, that was the patch. I forgot. I am getting confused over which
patches are finished by the authors, and which are on hold because of
merge issues or open community discussion issues.

Rather than ask if patches are "completed", I think "finished" is a
better word, meaning the author has finished working on it, and it now
up to the community on how to proceed.

--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://www.enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +

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