Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support

[Paolo Bonzini]

Il 14/08/2014 12:46, Kevin Wolf ha scritto:
> So to finally reply with some numbers... I'm running fio tests based on
> Ming's configuration on a loop-mounted tmpfs image using dataplane.

I'm not sure tmpfs is a particularly useful comparison, since it doesn't
support O_DIRECT.  O_DIRECT over ramdisk ("modprobe brd rd_nr=1
rd_size=524288 max_part=1", either directly or via a filesystem) is
probably a better benchmark.

Also, I'm not sure how the I/O scheduler works over tmpfs.  A ramdisk
should just do the right thing.  (Are you using deadline or cfq?)

>                 | Random throughput | Sequential throughput
> ----------------+-------------------+-----------------------
> master          | 442 MB/s          | 730 MB/s
> base            | 453 MB/s          | 757 MB/s
> bypass (Ming)   | 461 MB/s          | 734 MB/s
> coroutine       | 468 MB/s          | 716 MB/s
> bypass (Paolo)  | 476 MB/s          | 682 MB/s

This is pretty large, but it really smells like either a setup problem
or a kernel bug...

Paolo