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Re: [Qemu-devel] [PATCH v2 00/11] curl: fix curl read

From: Fam Zheng
Subject: Re: [Qemu-devel] [PATCH v2 00/11] curl: fix curl read
Date: Tue, 14 May 2013 16:50:19 +0800
User-agent: Mutt/1.5.21 (2010-09-15)

On Tue, 05/14 10:22, Stefan Hajnoczi wrote:
> On Tue, May 14, 2013 at 10:26:19AM +0800, Fam Zheng wrote:
> >  - CURLDataCache holds the user data read from libcurl, it is in a list
> >    ordered by access, the used cache is moved to list head on access, so
> >    the tail element is freed first. BDRVCURLState.cache_quota is the
> >    threshold to start freeing cache.
> Can you explain the need for a cache?
> The guest kernel already does readahead if it wants to.  It can be tuned
> from inside the guest if performance doesn't meet expectations.  The
> block/curl.c-specific cache cannot be tuned from the guest.

It's prefetch. If we send request for every read request, there'll be
too much overhead for protocal transactions.

I just name it CURLDataCache. Guest may have multiple sequencial reads,
so I used a list of it.

If you think this is reasonable, I'll update the commit messages on this.


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