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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: |
Wed, 15 May 2013 11:46:36 +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.
The guest may not do well on this. E.g. GRUB sends sequencial 2KB aio
requests loading the kernel of several MBs. This may make the curl
performs horribly to boot a guest from http served iso.
--
Fam
- [Qemu-devel] [PATCH v2 05/11] curl: add timer to BDRVCURLState, (continued)
- [Qemu-devel] [PATCH v2 05/11] curl: add timer to BDRVCURLState, Fam Zheng, 2013/05/13
- [Qemu-devel] [PATCH v2 06/11] curl: introduce CURLDataCache, Fam Zheng, 2013/05/13
- [Qemu-devel] [PATCH v2 07/11] curl: make use of CURLDataCache., Fam Zheng, 2013/05/13
- [Qemu-devel] [PATCH v2 08/11] curl: use list to store CURLState, Fam Zheng, 2013/05/13
- [Qemu-devel] [PATCH v2 09/11] curl: release everything on curl_close, Fam Zheng, 2013/05/13
- [Qemu-devel] [PATCH v2 10/11] curl: add cache quota., Fam Zheng, 2013/05/13
- [Qemu-devel] [PATCH v2 11/11] curl: introduce ssl_no_cert runtime option., Fam Zheng, 2013/05/13
- Re: [Qemu-devel] [PATCH v2 00/11] curl: fix curl read, Stefan Hajnoczi, 2013/05/14