Re: [Xen-devel] [PATCH v5 00/10] xen-block: multi hardware-queues/rings support

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Sat, Nov 14, 2015 at 11:12:09AM +0800, Bob Liu wrote:
> Note: These patches were based on original work of Arianna's internship for
> GNOME's Outreach Program for Women.
> 
> After using blk-mq api, a guest has more than one(nr_vpus) software request
> queues associated with each block front. These queues can be mapped over 
> several
> rings(hardware queues) to the backend, making it very easy for us to run
> multiple threads on the backend for a single virtual disk.
> 
> By having different threads issuing requests at the same time, the performance
> of guest can be improved significantly.
> 
> Test was done based on null_blk driver:
> dom0: v4.3-rc7 16vcpus 10GB "modprobe null_blk"

Surely v4.4-rc1?

> domU: v4.3-rc7 16vcpus 10GB

Ditto.

> 
> [test]
> rw=read
> direct=1
> ioengine=libaio
> bs=4k
> time_based
> runtime=30
> filename=/dev/xvdb
> numjobs=16
> iodepth=64
> iodepth_batch=64
> iodepth_batch_complete=64
> group_reporting
> 
> Results:
> iops1: After commit("xen/blkfront: make persistent grants per-queue").
> iops2: After commit("xen/blkback: make persistent grants and free pages pool 
> per-queue").
> 
> Queues:                         1        4              8              16
> Iops orig(k):         810     1064            780             700
> Iops1(k):             810     1230(~20%)      1024(~20%)      850(~20%)
> Iops2(k):             810     1410(~35%)      1354(~75%)      1440(~100%)

Wholy cow. That is some contention on a lock (iops1 vs iops2). Thank you for
running these numbers.

> 
> With 4 queues after this series we can get ~75% increase in IOPS, and
> performance won't drop if incresing queue numbers.
> 
> Please find the respective chart in this link:
> https://www.dropbox.com/s/agrcy2pbzbsvmwv/iops.png?dl=0

Thank you for that link.



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel