Re: Poor read performance on high-end server

[Chris Mason <chris.mason@oracle.com>]

On Mon, Aug 09, 2010 at 04:45:45PM +0200, Freek Dijkstra wrote:
> Hi all,
> 
> Thanks a lot for the great feedback from before the weekend. Since one
> of my colleagues needed the machine, I could only do the tests today.
> 
> In short: just installing 2.6.35 did make some difference, but I was
> mostly impressed with the speedup gained by the hardware acceleration of
> the crc32c_intel module.
> 
> Here is some quick data.
> 
> Reference figures:
> 16* single disk (theoretical limit):     4092 MiByte/s
> fio data layer tests (achievable limit): 3250 MiByte/s
> ZFS performance:                         2505 MiByte/s
> 
> BtrFS figures:
> IOzone on 2.6.32:                         919 MiByte/s
> fio btrfs tests on 2.6.35:               1460 MiByte/s

Was this one with O_DIRECT?

> IOzone on 2.6.35 with crc32c:            1250 MiByte/s
> IOzone on 2.6.35 with crc32c_intel:      1629 MiByte/s
> IOzone on 2.6.35, using -o nodatasum:    1955 MiByte/s
> 
> For those finding this message and want a howto: the easiest way to use
> crc32c_intel is to add the module name to /etc/modules:
>  # echo "crc32c_intel" >> /etc/modules
>  # reboot
> 
> Now the next step for us is to tune the block sizes. We only did that
> preliminary, but now that we have a good knowledge of what software to
> use, we can start tuning that in more detail.
> 
> If there is interest on this list, I'll gladly post our results here.

Definitely, please do.

-chris