diskio low read performance

Michel Santos michel at lucenet.com.br
Sat Jan 13 03:53:50 PST 2007

Mark Kirkwood disse na ultima mensagem:
> Michel Santos wrote:
>> I hope somebody can help me. I upgraded recently my cache server (squid)
>> 4.11 to 6.2
>> I notice that my disk read performance seems to be low. I observe it by
>> reading diskio from net-snmp. I started to check this because my old
>> server gave much better results from cache.
>> I see read access as 1/4 - 1/6 of write access. My cache_dirs are full
>> and
>> no swap in use. IOLA is not over 25-30 in peaks
>> is there some special configuration to get better read performance on
>> 6.2?
>> My disks are UW320 10k on Adaptec 29320 and the same as on the 4.11
>> server. I really dont care about write speed so much so if there are
>> parameters to configure I apreciate to hear about.
>> I checked the following with 1 and 0 but it does not make any difference
>> at all
>> vfs.write_behind
>> vfs.vmiodirenable
>> I get an average of 6-8Mb/s through this server and 3-4 of it is http
>> traffic. I see the object are going into the cache but for some reason
>> it
>> seems they can not be read in time.
>> I tried different newfs -b and -f and actually 1024/4096 seems to be
>> best.
>> I do not cache large files on this machine.
>> Is there something I sgould try?
> Note sure this will help you, as your files are all small, but try
> increasing vfs.read_max (say 16 or 32).

I forgot to say that I tried it already. Even if it gave me no improvement
I have it in 16 at this time together with a higher vfs.ufs.dirhash_maxmem

Sincerley, any of the configuration changes I did gave me absolutely
nothing in relationship to the disk read access performance. That is

Should I go back and try ufs1 perhaps? Or is it that squid does not work
well on 6.2?

I use diskd but in order to check if there is a SHM issue I tried ufs and
aufs, but also no difference at all. On 6.2 I do not even get close to 50%
of 4.11 disk read performance.

thank you

computador é como nem cavalo e mulher
mais que montam neles, pior que ficam ...

Datacenter Matik http://datacenter.matik.com.br
E-Mail e Data Hosting Service para Profissionais.

More information about the freebsd-performance mailing list