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Re: Poor SSD write performance (new install)

On Tue, Sep 10, 2013 at 09:42:40AM +0000, Nick LaForge wrote:
> What is puzzling is: if the performance loss is not likely to be related to
> any filesystem implementation / option, one logical hypothesis is that the
> partitions are not aligned to 4k blocks, but this has already been
> falsified by booting Linux and observing better performance for the exact
> same ext2 partition.

I'm not sure that NetBSD's ext2 implementation has received as much
performance tuning as the ffs file-system. So you are better of comparing
NetBSD's ffs to a suitable Linux file-system e.g. ext3 or ext4.

> I can only think that the loss of performance is related to the NetBSD
> kernel's idea of the entire disk (/dev/wd0).  E.g., dma is not being
> utilized, or maximum sata data rates are not taken advantage of, etc.  This
> is also strange, since the machine is not new (it is from 2009).

The kernel message you provided suggests that DMA is used:

        wd0(piixide0:0:0): using PIO mode 4, Ultra-DMA mode 4 (Ultra/66) (using 

You could however try to change the BIOS settings and configure the
SATA ports to use AHCI mode.

        Kind regards

Matthias Scheler                        

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