Re: [PERFORM] Caching by Postgres

2005-08-26 Thread Thomas Ganss
The first, to always remember - is that the move from 64-bits to 32-bits doesn't come for free. In a real 64-bit system with a 64-bit operating system, and 64-bit applications, pointers are now double their 32-bit size. This means more bytes to copy around memory, and in an extreme case, has

Re: [PERFORM] Caching by Postgres

2005-08-24 Thread Donald Courtney
Great discussion and illuminating for those of us who are still learning the subtleties of postGres. William To be clear - I built postgreSQL 8.1 64K bit on solaris 10 a few months ago and side by side with the 32 bit postgreSQL build saw no improvement. In fact the 64 bit result was

Re: [PERFORM] Caching by Postgres

2005-08-24 Thread Stephen Frost
* Donald Courtney ([EMAIL PROTECTED]) wrote: To be clear - I built postgreSQL 8.1 64K bit on solaris 10 a few months ago and side by side with the 32 bit postgreSQL build saw no improvement. In fact the 64 bit result was slightly lower. That makes some sense actually. It really depends on

Re: [PERFORM] Caching by Postgres

2005-08-24 Thread PFC
Really? Cool, I'd like to see that. Could you follow up with Hans? Or give me his e-mail? You can subscribe to the Reiser mailinglist on namesys.com or : [EMAIL PROTECTED] ---(end of broadcast)--- TIP 1: if posting/reading

Re: [PERFORM] Caching by Postgres

2005-08-24 Thread mark
On Wed, Aug 24, 2005 at 09:21:12AM -0400, Donald Courtney wrote: I built postgreSQL 8.1 64K bit on solaris 10 a few months ago and side by side with the 32 bit postgreSQL build saw no improvement. In fact the 64 bit result was slightly lower. I've had this sort of argument with a friend of

Re: [PERFORM] Caching by Postgres

2005-08-24 Thread William Yu
Donald Courtney wrote: I built postgreSQL 8.1 64K bit on solaris 10 a few months ago and side by side with the 32 bit postgreSQL build saw no improvement. In fact the 64 bit result was slightly lower. I'm not surprised 32-bit binaries running on a 64-bit OS would be faster than

Re: [PERFORM] Caching by Postgres

2005-08-24 Thread Alan Stange
[EMAIL PROTECTED] wrote: So then we move on to what 64-bit is really useful for. Obviously, there is the arithmetic. If you were previously doing 64-bit arithmetic through software, you will notice an immediate speed improvement when doing it through hardware instead. If you have a program that

Re: [PERFORM] Caching by Postgres

2005-08-24 Thread mark
On Wed, Aug 24, 2005 at 02:47:09PM -0400, Alan Stange wrote: At least on Sparc processors, v8 and newer, any double precision math (including longs) is performed with a single instruction, just like for a 32 bit datum. Loads and stores of 8 byte datums are also handled via a single

Re: [PERFORM] Caching by Postgres

2005-08-24 Thread PFC
At least on Sparc processors, v8 and newer, any double precision math (including longs) is performed with a single instruction, just like for a 32 bit datum. Loads and stores of 8 byte datums are also handled via a single instruction. The urban myth that 64bit math is

Re: [PERFORM] Caching by Postgres

2005-08-24 Thread Michael Stone
On Wed, Aug 24, 2005 at 03:34:41PM -0400, [EMAIL PROTECTED] wrote: It isn't an urban myth that 64-bit math on a 64-bit processor is faster, at least if done using registers. It definately is faster. It may be an urban myth, though, that most applications perform a sufficient amount of 64-bit

Re: [PERFORM] Caching by Postgres

2005-08-24 Thread mark
On Wed, Aug 24, 2005 at 05:09:04PM -0400, Alan Stange wrote: The older 32bit RISC processors do have 64 bit registers, ALUs and datapaths, and they are marketed toward high end scientific computing, and you're claiming that such a processor is slower than one which has the addition of 64

Re: [PERFORM] Caching by Postgres

2005-08-23 Thread John A Meinel
gokulnathbabu manoharan wrote: Hi all, I like to know the caching policies of Postgresql. What parameter in the postgresql.conf affects the cache size used by the Postgresql? As far as I have searched my knowledge of the parameters are In general, you don't. The OS handles caching based on

Re: [PERFORM] Caching by Postgres

2005-08-23 Thread Josh Berkus
John, So I'm guessing that with 8.1 there would be 2 sweet spots. Low shared_buffers (= 10k), and really high shared buffers (like all of available ram). But because postgres has been tuned for the former I would stick with it (I don't think shared_buffers can go 2GB, but that might just be

Re: [PERFORM] Caching by Postgres

2005-08-23 Thread Bruno Wolff III
On Tue, Aug 23, 2005 at 10:10:45 -0700, gokulnathbabu manoharan [EMAIL PROTECTED] wrote: Hi all, I like to know the caching policies of Postgresql. What parameter in the postgresql.conf affects the cache size used by the Postgresql? As far as I have searched my knowledge of the

Re: [PERFORM] Caching by Postgres

2005-08-23 Thread Donald Courtney
I mean well with this comment - This whole issue of data caching is a troubling issue with postreSQL in that even if you ran postgreSQL on a 64 bit address space with larger number of CPUs you won't see much of a scale up and possibly even a drop. I am not alone in having the *expectation*

Re: [PERFORM] Caching by Postgres

2005-08-23 Thread Josh Berkus
Donald, This whole issue of data caching is a troubling issue with postreSQL in that even if you ran postgreSQL on a 64 bit address space with larger number of CPUs you won't see much of a scale up and possibly even a drop. Since when? Barring the context switch bug, you're not going to

Re: [PERFORM] Caching by Postgres

2005-08-23 Thread mark
On Tue, Aug 23, 2005 at 02:41:39PM -0400, Donald Courtney wrote: I mean well with this comment - This whole issue of data caching is a troubling issue with postreSQL in that even if you ran postgreSQL on a 64 bit address space with larger number of CPUs you won't see much of a scale up and

Re: [PERFORM] Caching by Postgres

2005-08-23 Thread Michael Stone
On Tue, Aug 23, 2005 at 12:38:04PM -0700, Josh Berkus wrote: which have a clear and measurable effect on performance and are fixable without bloating the PG code. Some of these issues (COPY path, context switching Does that include increasing the size of read/write blocks? I've noticed that

Re: [PERFORM] Caching by Postgres

2005-08-23 Thread Chris Browne
[EMAIL PROTECTED] (Donald Courtney) writes: I mean well with this comment - This whole issue of data caching is a troubling issue with postreSQL in that even if you ran postgreSQL on a 64 bit address space with larger number of CPUs you won't see much of a scale up and possibly even a drop.

Re: [PERFORM] Caching by Postgres

2005-08-23 Thread Chris Browne
[EMAIL PROTECTED] (Michael Stone) writes: On Tue, Aug 23, 2005 at 12:38:04PM -0700, Josh Berkus wrote: which have a clear and measurable effect on performance and are fixable without bloating the PG code. Some of these issues (COPY path, context switching Does that include increasing the

Re: [PERFORM] Caching by Postgres

2005-08-23 Thread William Yu
Donald Courtney wrote: in that even if you ran postgreSQL on a 64 bit address space with larger number of CPUs you won't see much of a scale up and possibly even a drop. I am not alone in having the *expectation* What's your basis for believing this is the case? Why would PostgreSQL's

Re: [PERFORM] Caching by Postgres

2005-08-23 Thread PFC
Josh Berkus has already mentioned this as conventional wisdom as written by Oracle. This may also be legacy wisdom. Oracle/Sybase/etc has been around for a long time; it was probably a clear performance win way back when. Nowadays with how far open-source OS's have advanced, I'd take it

Re: [PERFORM] Caching by Postgres

2005-08-23 Thread Josh Berkus
PFC, Now, Hans Reiser has expressed interest on the ReiserFS list in tweaking   his Reiser4 especially for Postgres. In his own words, he wants a Killer app for reiser4. Reiser4 will offser transactional semantics via a special reiser4 syscall, so it might be possible, with a minimum

Re: [PERFORM] Caching by Postgres

2005-08-23 Thread Gavin Sherry
On Wed, 24 Aug 2005, PFC wrote: Josh Berkus has already mentioned this as conventional wisdom as written by Oracle. This may also be legacy wisdom. Oracle/Sybase/etc has been around for a long time; it was probably a clear performance win way back when. Nowadays with how far open-source

Re: [PERFORM] Caching by Postgres

2005-08-23 Thread Tom Lane
Gavin Sherry [EMAIL PROTECTED] writes: A filesystem could, in theory, help us by providing an API which allows us to tell the file system either: the way we'd like it to read ahead, the fact that we don't want it to read ahead or the way we'd like it to cache (or not cache) data. The thing is,

Re: [PERFORM] Caching by Postgres

2005-08-23 Thread Gavin Sherry
On Wed, 24 Aug 2005, Tom Lane wrote: Gavin Sherry [EMAIL PROTECTED] writes: A filesystem could, in theory, help us by providing an API which allows us to tell the file system either: the way we'd like it to read ahead, the fact that we don't want it to read ahead or the way we'd like it to