Messages in this thread | | | Date | Fri, 12 Dec 2003 15:32:29 -0800 (PST) | From | markw@osdl ... | Subject | Re: more dbt-2 results hyperthreading on linux-2.6.0-test11 |
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Hi Jun,
DBT-2 is a fair use implementation of the TPC-C (OLTP), if you're familiar with that.
I have 14 drives attached through 1 megaraid raid controller, and 52 drives connected through 4 channels on 2 mylex raid controllers, all in a raid-0 configuration. I am using LVM2 on both sets of drives.
iostat tells me that each of the 14 drives attached through the raid controller are utilized < 2%, while each of the other 52 drives seem to peak at about 48% in one of the hyperthreaded cases (274). I'm not too familiar with the umpteen other columns that iostat reports, but that suggests to me I have a fair amount of i/o headroom. Unfortunitely, I don't believe I can get my hands on any addition drives or controllers...
Mark
On 12 Dec, Nakajima, Jun wrote: > I'm not familiar with this particular workload, but noticed higher idle > and wait time with HT enabled, compared to HT-disabled case. This kind > of symptom often indicated insufficient I/O bandwidth from my > experience, and faster systems (with more threads) tend to show lower > throughput because you end up measuring disk seek time of more I/O > requests. Can you add more disk controller(s) and disks? > > Jun >> -----Original Message----- >> From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel- >> owner@vger.kernel.org] On Behalf Of markw@osdl.org >> Sent: Friday, December 12, 2003 2:28 PM >> To: piggin@cyberone.com.au >> Cc: mingo@redhat.com; linux-kernel@vger.kernel.org; pgsql- >> hackers@postgresql.org >> Subject: more dbt-2 results hyperthreading on linux-2.6.0-test11 >> >> Hi Nick, >> >> Here are the results of the comparisons I said I would do. >> >> no-hyperthreading: >> http://developer.osdl.org/markw/dbt2-pgsql/282/ >> - metric 2288.43 >> - baseline >> >> hyperthreading: >> http://developer.osdl.org/markw/dbt2-pgsql/278/ >> - metric 1944.42 >> - 15% throughput decrease >> >> hyperthreading w/ Ingo's C1 patch: >> http://developer.osdl.org/markw/dbt2-pgsql/277/ >> - metric 1978.39 >> - 13.5% throughput decrease >> >> hyperthreading w/ Nick's w26 patch: >> http://developer.osdl.org/markw/dbt2-pgsql/274/ >> - metric 1955.91 >> - 14.5% throughput decrease >> >> It looks like there is some marginal benefit to your or Ingo's patches >> with a workload like DBT-2. I probably don't understand enough about >> hyperthreading, but I wonder if there's something PostgreSQL can do to >> take advantage of hyperthreading >> >> Anyway, each link has pointers to readprofile and annotated oprofile >> assembly output (if you find that useful.) I haven't done enough > tests >> to have an idea of the error margin, but I wouldn't be surprised if > it's >> at least 1%. >> >> Let me know if there's anything else you'd like me to try. >> >> Thanks, >> Mark
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