Date: Tue, 25 Apr 2006 13:28:50 +0100 From: "Martin Hepworth" <maxsec@gmail.com> To: "Bill Moran" <wmoran@potentialtech.com> Cc: freebsd-questions@freebsd.org Subject: Re: Purchasing the correct hardware: dual-core intel? Big cache? Message-ID: <72cf361e0604250528r717ada4bybfe575986bd9f11d@mail.gmail.com> In-Reply-To: <20060424181953.6bfa6d1d.wmoran@potentialtech.com> References: <20060424154617.9dc28c94.wmoran@potentialtech.com> <72cf361e0604241503x6869f8cua7b3ddaa3d70bc4@mail.gmail.com> <20060424181953.6bfa6d1d.wmoran@potentialtech.com>
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Bill if the database is CPU dependant I'd look at tuning the queries/indexes and that stuff...it really shouldn't be CPU bound. -- martin On 4/24/06, Bill Moran <wmoran@potentialtech.com> wrote: > > On Mon, 24 Apr 2006 23:03:59 +0100 > "Martin Hepworth" <maxsec@gmail.com> wrote: > > > Bill > > > > depends on the application itself, but more RAM and the disk layout > (RAID) > > will be more important than the CPU. Also depends on how write-heavy th= e > > apps are... > > Thanks for the feedback, Martin. > > I'm fully aware of the app-dependency - what I'm looking for is a way > to test the application. I've got 3 different clusters available for > testing, but I'm not sure how to tell if the cache is getting used > heavily or not. > > I've already determined that the database server is CPU-bound under > our test load. With high-speed SCSI disks and battery-backed RAID, > there's not enough IO to stress the disk subsystem. RAM is almost a > non-issue. With the machine stressed at full load, it's only using > 1/8 of the available RAM. > > So, my current bottleneck is CPU power. And the boss has asked me > for the best way to overcome this bottleneck. We're looking at either > the same CPUs we already have, but with _huge_ caches (8m) - or going > with more CPUs by getting true dual-core pentiums. > > The question this all pivots on is will 8M of cache be a significant > improvement? If not, then we're going with the dual-core CPUs. What > I'd like is some way to take an existing system and determine how often > the cache is getting invalidated, so I can make some guesstemate as to > whether more cache will help or not. > > > > > -- > > martin > > > > On 4/24/06, Bill Moran <wmoran@potentialtech.com> wrote: > > > > > > > > > I've been asked to make some hardware recommendations, I'm hoping som= e > > > folks on the list can make some suggestions. > > > > > > We're looking hard at getting either Intel dual-core procs, or gettin= g > > > hyperthreaded procs with huge (8M) caches. > > > > > > We currently have a few dual proc Intel HT machines that we can test > > > out our workload on, and I'm trying to get a feel for how to determin= e > > > if a larger cache size will generate better performance than replacin= g > > > HT procs with full-blown dual-core procs. We're looking at the 6850 > > > from Dell, which supports both processor families: > > > > > > > http://www1.us.dell.com/content/products/productdetails.aspx/pedge_6850?c= =3Dus&cs=3D555&l=3Den&s=3Dbiz > > > > > > The goal for these machines is to serve out PosgreSQL databases to as > > > many Apache+php front ends as we can hang off each one. So we're > trying > > > to purchase hardware that will create a DB server that can handle a > lot > > > of web server front ends. > > > > > > I have a Dell 2850 (dual HT procs) here that I can use for testing. > > > I'm a little fuzzy on determining how well the cache is working, so > I'm > > > stuck on whether or not the 8M cache that's available on the HT units > > > is worth the money or not. Can anyone suggest a testing methodology > > > that will isolate this particular aspect? > > > > > > -- > > > Bill Moran > > > Collaborative Fusion Inc. > > > _______________________________________________ > > > freebsd-questions@freebsd.org mailing list > > > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > > > To unsubscribe, send any mail to " > > > freebsd-questions-unsubscribe@freebsd.org" > > > > > _______________________________________________ > > freebsd-questions@freebsd.org mailing list > > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > > To unsubscribe, send any mail to " > freebsd-questions-unsubscribe@freebsd.org" > > > > * > > > > > > > > > > > *************************************************************************= *********** > > This footnote confirms that this email message has been scanned by > > PineApp Mail-SeCure for the presence of malicious code, vandals & > computer viruses. > > > *************************************************************************= *********** > > > > > > > -- > Bill Moran > Collaborative Fusion Inc. > > **************************************************************** > IMPORTANT: This message contains confidential information and is > intended only for the individual named. 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