April 10, 2008 at 9:04 am
so question - x32 using awe then page lookups must swap through physical memory to get at the buffer cache. So what sort of figure would be good for page lookups/sec , or come to that what approaches the physical limits of this process?
In short I have minimal physical io as there is enough memory to put the whole database in ram, so what are upper and lower limits for page lookups?
10K/sec, 100k/sec 1 million/sec ?
ta.
[font="Comic Sans MS"]The GrumpyOldDBA[/font]
www.grumpyolddba.co.uk
http://sqlblogcasts.com/blogs/grumpyolddba/
April 10, 2008 at 9:10 am
It will obviously depend on the speed of your processors, memory, and front-side bus.
I have seen speeds in excess of 100K pages/sec on servers with fairly average specs. I have never seen anything approaching 1 million/sec.
April 10, 2008 at 12:46 pm
yup, that's what I figured as despite my best efforts I couldn't seem to find any way to calculate this.
I have a hunch that around 270k/sec is the best value for my box and once the figure gets to around 350k/sec it's struggling - BUT - I don't know if this is just a result of a very busy server or an actual bottleneck.
[font="Comic Sans MS"]The GrumpyOldDBA[/font]
www.grumpyolddba.co.uk
http://sqlblogcasts.com/blogs/grumpyolddba/
April 10, 2008 at 1:02 pm
270K/sec sounds pretty good.
That means it can lookup 2GB/sec of data pages, so it is capable of fast scans of fairly large tables.
April 10, 2008 at 2:25 pm
yup did the maths too - but is 2gb / sec ( through awe ) a bottleneck ? It's the usual problem with perfmon counters - there's often just no way to know if a value is good or bad, as they often depend upon the hardware. I think that maybe 2gb/sec is possibly the upper figure for my server. Essentially my entire database sits in memory.
[font="Comic Sans MS"]The GrumpyOldDBA[/font]
www.grumpyolddba.co.uk
http://sqlblogcasts.com/blogs/grumpyolddba/
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