Message-ID: <5A4C9BAC.3040808@intel.com>
Date: Wed, 03 Jan 2018 17:00:28 +0800
From: Wei Wang <wei.w.wang@intel.com>
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To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
        willy@infradead.org
CC: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org,
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        liliang.opensource@gmail.com, yang.zhang.wz@gmail.com,
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Subject: Re: [PATCH v20 4/7] virtio-balloon: VIRTIO_BALLOON_F_SG
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On 01/03/2018 10:29 AM, Tetsuo Handa wrote:
> Matthew Wilcox wrote:
>> 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