Re: Cached file read performance
- From: Eric Anderson <anderson@xxxxxxxxxxxx>
- Date: Thu, 21 Dec 2006 23:16:41 -0600
On 12/21/06 19:35, Mark Kirkwood wrote:
I recently did some testing on the performance of cached reads using two (almost identical) systems, one running FreeBSD 6.2PRE and the other running Gentoo Linux - the latter acting as a control. I initially started a thread of the same name on -stable, but it was suggested I submit a mail here.
My background for wanting to examine this is that I work with developing database software (postgres internals related) and cached read performance is pretty important - since we typically try hard to encourage cached access whenever possible.
Anyway on to the results: I used the attached program to read a cached 781MB file sequentially and randomly with a specified block size (see below). The conclusion I came to was that our (i.e FreeBSD) cached read performance (particularly for smaller block sizes) could perhaps be improved... now I'm happy to help in any way - the machine I've got running STABLE can be upgraded to CURRENT in order to try out patches (or in fact to see if CURRENT is faster at this already!)...
Best wishes
Mark
----------------------results-etc---------------------------------
Machines
========
FreeBSD (6.2-PRERELEASE #7: Mon Nov 27 19:32:33 NZDT 2006):
- Supermicro P3TDER
- 2xSL5QL 1.26 GHz PIII
- 2xKingston PC133 RCC Registered 1GB DIMMS
- 3Ware 7506 4x Maxtor Plus 9 ATA-133 7200 80G
- Kernal GENERIC + SMP
- /etc/malloc.conf -> >aj
- ufs2 32k blocksize, 4K fragments
- RAID0 256K stripe using twe driver
Gentoo (2.6.18-gentoo-r3 ):
- Supermicro P3TDER
- 2xSL5QL 1.26 GHz PIII
- 2xKingston PC133 RCC Registered 1GB DIMMS
- Promise TX4000 4x Maxtor plus 8 ATA-133 7200 40G
- default make CFLAGS (-O2 -march-i686)
- xfs stripe width 2
- RAID0 256K stripe using md driver (software RAID)
Given the tests were about cached I/O, the differences in RAID controller and the disks themselves were seen as not significant (indeed booting the FreeBSD box with the Gentoo livecd and running the tests there confirmed this).
[..snip of useful results..]
Aren't you also slightly testing parts of the file system code? Why not (since it is only read-only you are interested in) use FreeBSD's xfs support (only in -CURRENT however) and run the tests also? I'm just curious if it would make any difference - I would bet not much of any though.
Eric
--
------------------------------------------------------------------------
Eric Anderson Sr. Systems Administrator Centaur Technology
An undefined problem has an infinite number of solutions.
------------------------------------------------------------------------
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- From: Mark Kirkwood
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