[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Xen-devel] [PATCH 0/3] qemu-qdisk: Replace grant map by grant copy.


It is a proposition for implementation of the replacement of the grant map 
operation with grant copy. 

I would appreciate an opinion about the approach if is proper or maybe 
I assumed something wrongly, and if you see any possibility of improvement
or the things that need to be change.
If the approach is any good, I need to still rethink batch mode, notification 
and implementation for mini-os.

In the libs, gnttab, linbxc there is added interface and invocation of 
an ioctl(gntdev, IOCTL_GNTDEV_GRANT_COPY, ..) system call on the gnttdev 
Described in details in the following messages. It is not implemented for 

The grant map operation is replaced on the behalf of grant copy in 
qemu-xen-dir/hw/block/xen_disk. The implementation is described in the patch.

For the functional test I attached the device with a qdisk backend to the guest.
I successfully mounted it and stored files there. During creation of 
a file system on the device BLKIF_OP_DISCARD operation seems to fail(ret value 
different then zero) but it also fails for the original version due to error 
return from qemu.

I made fio tests before[0] and after[1] the changes with different iodepth and 
size of the block. The test which I run can be accessed on my github[2] but 
mainly after the warm up I run for 60 seconds:
    fio --time_based \
                --clocksource=clock_gettime \
                --rw=randread \
                --random_distribution=pareto:0.9 \
                --size=10g \
            --direct='1' \
            --ioengine=libaio \
                --filename=$DEV \
                --iodepth=$IODEPTH \
                --bs=$BS \
                --name=$NAME \
                --runtime=$RUNTIME >> $FILENAME
The test were repeated at least three times. 

Although before the changes results looks coherent for me, after there are
considerable peaks for iodepth = {4,8}.

    - domU sheets
[2] https://github.com/paulina-szubarczyk/xen-benchmark
    - multitest_with_iodepth.sh

Thanks and regards, 

Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.