I've done some further looking aruond at this, and I've been unable to find
any references to disk systems with sector size 8192 bytes (which is what
the alignment of the buffers per XLOG_BLCKSZ, at leastby default).
So I'll commit this fairly simple patch, and we'll revert it or add runtime
Patch applied by Magnus.
---
ITAGAKI Takahiro wrote:
The attached is a patch to define O_DIRECT by ourselves on Windows,
and to map O_DIRECT to FILE_FLAG_NO_BUFFERING.
There will be a consistency in our support between
Your patch has been added to the PostgreSQL unapplied patches list at:
http://momjian.postgresql.org/cgi-bin/pgpatches
It will be applied as soon as one of the PostgreSQL committers reviews
and approves it.
---
IIRC, we're still waiting for performance numbers showing there exists a
win from this patch.
//Magnus
Bruce Momjian wrote:
Magnus, where are on this?
---
Magnus Hagander wrote:
We're ok with the alignment issues
Are there any performance numbers on this?
---
ITAGAKI Takahiro wrote:
The attached is a patch to define O_DIRECT by ourselves on Windows,
and to map O_DIRECT to FILE_FLAG_NO_BUFFERING.
There will be a consistency in
We're ok with the alignment issues provided the is code added to reject
O_DIRECT if the sector size is too large.
We also said we need to see some performance numbers on the effect of
the patch before it goes in.
//Magnus
Bruce Momjian wrote:
So, do we want this patch? Are we OK on WIN32
So, do we want this patch? Are we OK on WIN32 alignment issues?
---
ITAGAKI Takahiro wrote:
The attached is a patch to define O_DIRECT by ourselves on Windows,
and to map O_DIRECT to FILE_FLAG_NO_BUFFERING.
There will
People seem to be confusing sector size and cluster size.
Microsoft Windows assumes sectors are 8k or less on hard drives (99% are
512 bytes).
Do you have any doc ref for this? I beleive you but I've been searching for
docs on that and found nothing.
Cluster size is the allocation unit.
I think many people can benefit from Itagaki-san's proposal, and
NO_BUFFERING should be default. Isn't it very rare that disks with
sector size larger than 8KB are used?
Definitly very rare.
Providing a way (such as
wal_sync_method) to avoid NO_BUFFERING is sufficient for people
PM
To: Takayuki Tsunakawa; Magnus Hagander
Cc: ITAGAKI Takahiro; pgsql-patches@postgresql.org
Subject: Re: [pgsql-patches] O_DIRECT support for Windows
People seem to be confusing sector size and cluster size.
Microsoft Windows assumes sectors are 8k or less on hard drives (99% are
512 bytes
On Tue, Jan 16, 2007 at 10:59:11AM +0900, Takayuki Tsunakawa wrote:
From: Magnus Hagander [EMAIL PROTECTED]
ITAGAKI Takahiro wrote:
Do you mean there are drives that have larger sector size than 8kB?
We've already put the xlog buffer along the alignment of
ALIGNOF_XLOG_BUFFER (typically
Hello, Magnus-san, Itagaki-san
From: Magnus Hagander [EMAIL PROTECTED]
I think many people can benefit from Itagaki-san's proposal, and
NO_BUFFERING should be default. Isn't it very rare that disks with
sector size larger than 8KB are used?
Definitly very rare.
Providing a way (such as
Of Takayuki
Tsunakawa
Sent: Tuesday, January 16, 2007 4:53 PM
To: Magnus Hagander
Cc: ITAGAKI Takahiro; pgsql-patches@postgresql.org
Subject: Re: [pgsql-patches] O_DIRECT support for Windows
Hello, Magnus-san, Itagaki-san
From: Magnus Hagander [EMAIL PROTECTED]
I think many people can benefit from
The attached is a patch to define O_DIRECT by ourselves on Windows,
and to map O_DIRECT to FILE_FLAG_NO_BUFFERING.
There will be a consistency in our support between Windows and other OSes
that have O_DIRECT. Also, there is the following comment that says, I read,
we should do so.
| handle other
On Mon, Jan 15, 2007 at 05:36:09PM +0900, ITAGAKI Takahiro wrote:
The attached is a patch to define O_DIRECT by ourselves on Windows,
and to map O_DIRECT to FILE_FLAG_NO_BUFFERING.
There will be a consistency in our support between Windows and other OSes
that have O_DIRECT. Also, there is
Magnus Hagander [EMAIL PROTECTED] wrote:
FILE_FLAG_NO_BUFFERING requires that *all* I/O follows:
* File access must begin at offsets that are integer multples of the
volume sector size.
* File access must be for number of bytes that are integer multiples of
the volume sector size.
*
ITAGAKI Takahiro wrote:
Magnus Hagander [EMAIL PROTECTED] wrote:
FILE_FLAG_NO_BUFFERING requires that *all* I/O follows:
* File access must begin at offsets that are integer multples of the
volume sector size.
* File access must be for number of bytes that are integer multiples of
the
From: Magnus Hagander [EMAIL PROTECTED]
ITAGAKI Takahiro wrote:
Do you mean there are drives that have larger sector size than 8kB?
We've already put the xlog buffer along the alignment of
ALIGNOF_XLOG_BUFFER (typically 8192 bytes).
But if there are such drives, using FILE_FLAG_NO_BUFFERING
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