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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