Re: to fsync or not to fsync (ext3?)

Frank, thanks for your answer,

This article http://www.linuxjournal.com/print.php?sid=5841 evaluates
performance from a relational database point of view and it concludes
that ext3 is faster.
The articles you provided evaluate filesystems by using basic shell
commands, copy, tar, touch.
I really don't know why ext3 would be faster for databases but here are
some tests that suggest this is true,

I run pgbench with data=writeback for ext3, this is as ext2 as an ext3
fs can get, and results are more or less the same as with data=journal

Best run with data=journal
------------------------------------

[root@dbs pgbench]# ./pgbench -U dba -P 4ghinec osdb -c 10 -s 11 -t 1000
starting vacuum...end.
transaction type: TPC-B (sort of)
scaling factor: 1
number of clients: 10
number of transactions per client: 1000
number of transactions actually processed: 10000/10000
tps = 349.844978 (including connections establishing)
tps = 350.715286 (excluding connections establishing)


Best run with data=writeback
----------------------------------------

[root@dbs pgbench]# ./pgbench -U dba -P 4ghinec osdb -c 10 -s 11 -t 1000
starting vacuum...end.
transaction type: TPC-B (sort of)
scaling factor: 1
number of clients: 10
number of transactions per client: 1000
number of transactions actually processed: 10000/10000
tps = 319.239210 (including connections establishing)
tps = 319.961564 (excluding connections establishing)

anybody else can throw some light on this?


Frank Hsueh wrote:

>Rodrigo,
>
>
>>Hello there, I'm trying to make sure my postgres 7.4 is running as fast
>>as it can in my box.
>>
>>
>>My Software config is:
>>
>>RedHat 7.3 - 2.4.20-28.7smp Kernel, reporting four processors because of
>>hyper threading.
>>Postgres 7.4
>>Data directory is on a ext3 journaled filesystem (data=journal)
>>
>>
>Isn't ext3 a really slow journaled filesystem [1, 2] to begin with?
>
>[1] http://slashdot.org/article.pl?sid=04/05/11/134214
>[2] http://209.81.41.149/~jpiszcz/index.html
>
>It might be a good experiment to figure out how different file systems
>affect perf.
>
>

Rodrigo Filgueira Prates
IT@CINTERFOR/OIT
http://www.cinterfor.org.uy