Re: HIGHMEM4G config for 1GB RAM on desktop?

[Timothy Miller]

Miquel van Smoorenburg wrote:
> In article <41336CB1.6030105@xxxxxxxxxxxxxx>,
> Timothy Miller  <miller@xxxxxxxxxxxxxx> wrote:
>
> > Timothy Miller wrote:
> >
> > > Hey, that rings a bell.  I have a 3ware 7000-2 controller with two 
> > > WD1200JB drives in RAID1.  I find that if I dd from the disk, I get 
> > > exactly the read throughput that is the max for the drives (47MB/sec). 
> > > However, if I do a WRITE test, the performance is miserable.
> > >
> > > I have been going back and forth with 3ware for months, and what's odd 
> > > is that my drives with my controller in any machine other than the 
> > > primary box get great write throughput, BUT on my main box with 1G of 
> > > RAM, I get MISERABLE write throughput.  When I should be getting 
> > > 36MB/sec or faster, I get 8 to 12 MB/sec.
> > >
> > > Now, I have tried limiting the memory with a mem= boot option, but that 
> > > doesn't change the performance any.
> >
> > Scratch all this.  Even if I physically remove half the memory, I STILL 
> > get the performance problem.
>
>
> 3ware eh?
>
> Try setting /sys/block/sda/queue/nr_requests to twice the number
> in /sys/block/sda/device/queue_depth


This will improve write performance?  And if this helps, how do I make 
it permanent?

Thanks!

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