Re: [PATCH v20 4/7] virtio-balloon: VIRTIO_BALLOON_F_SG

On 01/03/2018 10:29 AM, Tetsuo Handa wrote:

Matthew Wilcox wrote:

quoted

The radix tree convention is objectively awful, which is why I'm working
to change it.  Specifying the GFP flags at radix tree initialisation time
rather than allocation time leads to all kinds of confusion.  The preload
API is a pretty awful workaround, and it will go away once the XArray
is working correctly.  That said, there's no alternative to it without
making XBitmap depend on XArray, and I don't want to hold you up there.
So there's an xb_preload for the moment.

I'm ready to propose cvbmp shown below as an alternative to xbitmap (but
specialized for virtio-balloon case). Wei, can you do some benchmarking
between xbitmap and cvbmp?
----------------------------------------
cvbmp: clustered values bitmap

I don't think we need to replace xbitmap, at least at this stage. The 
new implementation doesn't look simpler at all, and virtio-balloon has 
worked well with xbitmap.

I would suggest you to send out the new implementation for discussion 
after this series ends, and justify with better performance results if 
you could get.

Best,
Wei