[sheepdog-users] cache performance test

[Liu Yuan]

On Tue, Jun 25, 2013 at 12:16:15PM +0200, Valerio Pachera wrote:
> sheep -w size=20000 /mnt/sheep/meta/,/mnt/sheep/dsk02
> 
> /mnt/sheep/meta is a ssd disk. Cache it stored here. No objects are
> stored on the same physical disk.
> /mnt/sheep/dsk02 is a mechanical sata disk, 7200 rpm like all the
> other hdd of the cluster.
> 
> This is my guest
>   qemu-system-x86_64 -enable-kvm -smp 2 -m 512 -drive
> file=sheepdog:squeeze,cache=writeback -drive
> file=sheepdog:big,cache=writeback
> and is running on the node with the ssd.
> 
> vdi named 'big' is formatted with ext4 and is where is write.
> 
> I compare the write speed of the guest using cache, with the write
> speed of the host writing directly on the ssd.
> 
> 
> 
> dd if=/dev/zero of=n bs=1M count=512 oflag=direct
> 
> Guest: 55 MB/s
> Host: 130 MB/s
> 

Please try following setup:
1 use vritio for guest, that is, -drive if=virtio at startup
2 echo 4096 > /sys/block/vda/queue/max_sectors_kb in the *guest*
3 use deadline io-sched for guest

With above setup, I guess the number will go higher.

> dd if=/dev/zero of=n bs=1M count=512
> 
> Guest: 103 MB/s
> Host: 302 MB/s

This is not valid because host has much more memory than guest.

Thanks,
Yuan